This drivetrain is centrally mounted, low maintenance, damage-resistant, and delivers up to twice the torque of current eBike motors.

Today, we’re talking about eCVT bicycles and why they might be the future of eBike tech. We’ll dive into how eCVTs work, their advantages and disadvantages, and the companies pushing this innovation forward.

The Evolution of eBike Drivetrains

eBikes are the fastest-growing bicycle category, and that boom has fuelled rapid development in motors and drivetrains.

E-bike motors are smaller, lighter, quieter, and more efficient than ever before. Power delivery is smoother, pickup speeds are quicker, and new innovations are changing their design.

One of those innovations is a fully integrated drivetrain where the motor and gearbox are built into one unit. This solution simplifies the drivetrain, weather seals the gear components, and improves the weight distribution of the bike.

Some integrated drivetrains have now taken it even further by stripping out the gearbox components and using an electronic continuously variable transmission (eCVT) instead.

eCVT Bicycle Drivetrains

An eCVT is just like other motor gearbox units, however, the difference is that it uses two electric motors and a planetary gear set to achieve variable gear ratios.

If that sounds like something from a hybrid car, you’re spot on. The design is similar to the eCVT used in vehicles like the Toyota Prius.

Here’s a brief explanation of how an eCVT works.

How Do eCVT Bicycles Work?

There are two motors in a bicycle eCVT.

• The direct motor provides pedal assist, like any standard mid-drive motor
• The speed ratio motor provides pedal assist, and it adjusts the bike’s gear ratio by spinning the front sprocket faster or slower via a planetary gear.

By adjusting the speed ratio motor to a very fine degree, the system can provide infinite gear options. These gears are changed smoothly and instantly, with zero rider interruption.

There are more advantages to eCVTs too.

The Advantages of eCVT Bicycles

Completely Effortless Riding

Riding with an eCVT is completely effortless, as they continuously adjust to keep you at your preferred cadence, no matter the speed or incline. All you have to do is choose a cadence you like, and the motor takes care of the rest. And should you come to a stop, the motor will automatically put you in the ideal gear for takeoff.

For those who prefer manual control, shift buttons will provide instant gear changes, even under a full pedal load. The shifting on these systems is faster than any other bicycle drivetrain – it takes just half a second to go from the lowest to the highest gear ratio.

Increased Durability & Reduced Maintenance

Durability and low maintenance are also major advantages. With fewer exposed parts and fully sealed internals, eCVTs are far less prone to damage than derailleur drivetrains. Additionally, there are significantly fewer components that wear out over time, which cuts down on servicing and replacement parts.

Some eCVTs support chainless drivetrains altogether, pairing with either drive shafts or belt drives instead of traditional chains. These alternatives are cleaner, quieter, and longer-lasting, further reducing the need for regular cleaning or adjustment.

High Torque Output & Reverse Mode

In terms of performance, these systems pack a serious punch, with their dual motors delivering up to 200Nm of torque, which is significantly more than most motors, and perfect for mountain bikes or fully laden cargo bikes.

And for those same cargo bikes, a unique benefit is the reverse mode. Because the system can spin the front chainring backward as well as forward, parking is especially easy.

Wide Gear Ranges and High Drive Efficiency

eCVTs also offer exceptionally wide gear ranges, up to 1000%, which means you can crawl up steep inclines and still cruise comfortably at high speeds. This range is roughly double that of most bicycle drivetrains.

Power transfer is handled more efficiently than with traditional CVTs, which often lose energy to friction in sliding pulleys or rotating spheres. Instead, eCVTs use motor control and planetary gear sets to deliver excellent overall efficiency.

Even better, eCVTs can constantly fine-tune the bike’s gear ratio for peak motor efficiency, helping you get the most out of every charge.

Regenerative Braking & Better Weight Distribution

Some systems go even further by incorporating regenerative braking. This means you can recover energy while braking or descending, extending battery range and reducing brake pad wear. In some designs, you can even back-pedal to slow the bike down.

And lastly, thanks to their centralised, mid-mounted design, eCVTs also contribute to improved weight distribution, which translates into better handling, especially on off-road terrain.

As you can see, eCVTs offer many benefits. But there are some trade-offs too.

The Disadvantages of eCVT Bicycles

Pedal Lag & Weight

There’s a slight delay (around 20 to 40 milliseconds) between your pedalling input and the motor response. It’s minor, but noticeable, similar to the difference between using a rear hub with 24 engagement points versus one with 72.

Weight is another factor. eCVTs tend to be heavier than a motor and derailleur combo. For example, a DJI Avinox system paired with a SRAM derailleur setup is roughly 500 to 1000 grams lighter than its eCVT counterpart.

Battery-Powered Shifting & Noise

These systems also rely entirely on battery power for gear shifting. If your battery dies, you could be stuck in the lowest gear. That said, most manufacturers build in a reserve capacity for enough shifts to get you home.

Noise may also be a drawback with this motor-gearbox configuration, as a dual-motor setup typically generates more sound than the best single-motor systems. That said, without large spur gears in the mix, overall noise levels remain relatively low.

Strange Pedalling Characteristics (Some Designs)

In some designs, the pedals drop to a resting position when stationary or without battery power. That could be a nuisance if the battery temporarily disconnects while riding, such as when hitting a bump.

Additionally, some entry-level eCVTs can feel less direct under high-torque situations. This is because you’re engaging the internal components (such as a belt or two) before you engage the external chain.

Difficult Repairs

And finally, repairs can be more complicated. With more electronics and sensors involved, fixing an eCVT usually requires a trained technician and specialised tools. As with any motorised system, it’d be prudent to only use a system with good local support.

Right, that’s the full list of trade-offs. Let’s now take a look at the companies pushing this technology forward.

Who’s Building eCVT Bicycle Drivetrains?

Revonte ONE

The first eCVT I want to show you is the Revonte ONE.

The stats are excellent on this unit with a monstrous 200Nm torque, 480% gear range, and 4.7kg weight. To put this weight in perspective, it’s heavier than the Pinion MGU (4.1kg) and Intradrive GD8 (4.5kg) but lighter than the Valeo Smart eBike System (4.9kg).

I tested a prototype Revonte ONE two years ago, and it was already performing exceptionally well. It shifted through the gears smoothly and unobtrusively, with only a very slight delay between pedalling and motor response.

A cool thing about the Revonte design is that the direct motor is set perpendicular to the speed ratio motor to minimise the packaging size.

Sadly, Revonte recently filed for bankruptcy. They’ve sold their intellectual property to another company in the eBike space, so expect it to reappear under another brand.

Owuru E2

Currently found in Decathlon bikes, the Owuru E2 is optimised for smooth city riding. It’s a touch lighter (4.6kg) than the Revonte, but it has a smaller gear range (265%) and less torque (65 to 120Nm).

The E2 has a different layout from other motors. The crank is connected to the planetary gear set via a belt, and the direct motor is connected to the gear set via a separate belt. The combined motors supply power to the small output sprocket.

As a result of its design, this motor feels a bit spongy under strong pedal input. That makes it great for cruising and less ideal for high-performance riding, which luckily, is not its intended use.

Driven Orbit Drive

Orbit Drive is a development from the team behind the wild Driven drivetrain, and it connects to the rear wheel via a drive shaft. By using a chainless drivetrain that’s protected from the elements, Driven reduces bike maintenance even further.

The specs are comparable to other eCVTs with a torque rating of 90Nm and a weight of 4.6kg.

However, Orbit Drive takes a completely different approach when it comes to design. The two motors are connected to a gear set just like normal, but instead of a planetary gear, this is a variable speed bevel differential built around the crank.

The direct motor is connected to a bevel gear on one side of the “orbit”, and the speed ratio motor connects to the other. When the speed ratio motor engages its side of the “orbit”, the output can spin faster.

One thing working against this design is that bevel gears inherently have higher losses than straight-cut gears, and there are a lot of them here. But if other aspects of drivetrain performance are excellent, a reduction in efficiency can easily be overlooked.

Villiger Dynamic Drive

Villiger Technik, known for its agricultural equipment, is entering the eBike world with a lightweight eCVT called Dynamic Drive.

It’s still in development, but the stats suggest a serious contender – it’s said to be 20% lighter than other motors (3.8kg), while offering 100Nm torque and over 1000% gear range.

Ellio

The last eCVT drivetrain you should know about is by Ellio. This Belgian company specialises in two-wheel drive eBikes that can travel at 45km/h.

The Ellio eCVT layout is completely different to the others as it has been built using modified e-bike parts. The direct motor is found at the front wheel, the speed ratio motor is above the crankset, and the planetary gear is in the rear hub. Two drive belts connect everything up.

Ellio bikes have fully automatic gear changing, regenerative braking and massive batteries for extra range. All you have to do is set your cadence (from 55 to 90 RPM) and the bike will do the rest.

Unique to this bike is a ‘cruise control’ feature, which maintains your cycling speed even as you vary your pedal inputs. And another cool feature only possible on a two-wheel drive bike is the traction control. Ellio bikes can identify wheel spin or loss of grip, and reduce the torque delivered to the wheel (or wheels) to regain traction.

Before I sum everything up, let’s quickly chat about why eCVT bicycles aren’t mainstream yet.

Why Aren’t eCVT Bicycles Mainstream?

Bringing a new motor and gear system to market is expensive and difficult. It takes years of R&D and millions in investment.

It typically requires the backing of a major company (like Bosch or Shimano) to get the technology off the ground. These brands have deep resources, tonnes of experience, and can quickly scale up production and secure partnerships to get their product out there.

Most eCVT projects are startups. While the technology is impressive, mass adoption will take time – unless a major player decides to bring it into their lineup.

Are eCVT Bicycles the Future of eBikes?

With automatic gear changes, seamless shifting, increased durability, and chainless drivetrain options, eCVTs offer compelling advantages.

There are still challenges to solve, like reducing weight, minimising pedal lag, and expanding service networks. But the potential is enormous.

As the tech matures and bigger brands get involved, I predict eCVT bicycles will become a common sight on roads, trails, and bike lanes in around a decade.

• Bicycle Drivetrains

Are Chainless Digital Drive Bicycles The Future of Cycling?

byAlee Denham

November 15, 2022

The post Are Chainless eCVT Bicycles The Future of eBike Tech? appeared first on CYCLINGABOUT.com.

Pinion currently leads the space with its robust gearboxes, which offer broader gear ranges and smaller gear steps than traditional derailleur systems. It remains the only brand featured in DH World Cup racing.

Meanwhile, Effigear has expanded the field with two distinct gearbox models of its own.

But a new wave of innovation is rapidly emerging.

In this article, I’ll walk you through various innovative designs – ranging from derailleur-in-a-box concepts to planetary systems, belt-and-pulley configurations, spur gear mechanisms, and even a unique chain-driven gearbox featuring hinged gear clusters.

Let’s dive in.

RatioX CVT Bicycle Gearbox

Let’s start with a fully automatic gearbox with no shifter, no cables, no battery, and no electronics! The RatioX transmission is a purely mechanical device that maintains your optimal pedalling cadence regardless of speed or gradient.

This type of gear system is known as a continuously variable transmission (CVT), and that means it can have not just 10 or 12 gears, but an infinite gear ratios between two set points. The system operates much like the belt-and-pulley setups found in scooters and snowmobiles.

Gearing adjustments are handled automatically via centrifugal forces acting on weights and springs, which vary the size of the pulleys. The transmission even remains synchronised with your coasting speed, ensuring you’re always in the ideal gear when you resume pedalling.

Belt and pulley gear CVTs are known to have a fair bit of drag, making RatioX best suited for eBikes with rear hub motors. In this configuration, the motor delivers propulsion directly to the wheel, so it’s only a bit of your pedal power that will be lost to drag.

The RatioX gearbox is lighter than a Pinion (2kg), has a 360% gear range, is housed in a watertight and dustproof casing, and uses grease instead of oil, reducing maintenance needs and eliminating leaks. It’s a clever mechanical gearbox that I hope gains some popularity.

You can read more about the RatioX bicycle gearbox on the RatioX website.

Peyman CVT Gearbox

The Peyman CVT is another fully mechanical, automatic gearbox that appears to be a more affordable alternative to the RatioX system.

Initially, Peyman developed a compact, belt-driven CVT mounted at the rear wheel – an approach that was retrofittable to any bike. More recently, they’ve shifted to a larger version integrated into the crankset. This updated design offers an impressive 1000% gear range, far surpassing that of any other current gearbox.

As crank speed and torque increase, the CVT visibly shifts to a higher ratio on the pulleys – it’s a fascinating process to watch. While the original rear-mounted version lacked the ability to maintain gear position during coasting (it automatically drops to the lowest ratio), the crankset-mounted prototype may offer a solution to this limitation.

Head over to PeymanCVT.co.uk for more.

Praxis HiT Gearbox

For a more lightweight and efficient gearbox solution, we turn to the Praxis HiT. Still in the prototype phase, this chain-driven gearbox incorporates hinged gear clusters – a concept enabled by Praxis’ acquisition of the Vyro 2X chainring patent.

Each gear cluster consists of a larger outer cog that folds over a smaller inner cog in four segments. This unique mechanism enables smooth shifting between gear sizes, even under high pedalling loads up to 1000 watts.

The HiT can be configured with anywhere from 4 to 16 speeds, depending on the number of clusters used, offering the potential for wide gear ranges. While the prototype uses an industrial chain, adopting a custom chain design could reduce the overall gearbox size by up to 25%.

Shifting is fully electronic and wireless, with support for both sequential and non-sequential shifting. This means you could go from the 1st gear to the 4th in one shift.

Thanks to its perfectly straight chainline, the system is expected to have low drivetrain drag. The efficiency is estimated to fall between 92% and 96%, as the system effectively combines two singlespeed drivetrains, each with losses of around 2 to 4% (eg. 0.98 × 0.98 = 0.96).

Another key advantage is its flexible integration: input and output placement can be adapted to suit various frame designs, from high-pivot mountain bikes to urban commuters.

You can learn more about the HiT bicycle gearbox on the Praxis website.

WRP Cassette In A Can

Williams Racing Products (WRP) has been teasing working prototypes of a derailleur in a box for a while.

The latest design is impressively compact, and it fits the Pinion 6-bolt mounting standard. While we can’t see inside, we can see that the input and output have now been moved to the crankshaft, and it uses two cables for shifting.

One cable is connected to an Archer D1X wireless shifter and remote, and I suspect the second cable is tensioned by a spring located inside the down tube. This spring would power one direction of the shifting, while tensioning both cables just like the spring in a derailleur.

It’s safe to assume the sprockets are very small, so don’t expect many speeds or a wide gear range on this one.

UNNO Derailleur In A Box

UNNO Bikes holds a patent for a derailleur-in-a-box, suggesting that functional prototypes may already exist.

What makes this system unique is that it doesn’t use a derailleur. Instead, the cassette itself moves side-to-side to change gears. While this is an innovative approach, it also presents packaging challenges, as the lateral movement of the cassette must be accommodated within the confines of the gearbox.

Nuseti Inner Drive System

Stepping away from traditional chains, we have a drivetrain entirely housed within the frame.

Nuseti has spent over a decade developing its Inner Drive System – a fully enclosed drivetrain designed for minimal maintenance, easy cleaning, and outstanding durability. With all gear components sealed inside the frame, they’re fully protected from the elements. This design also simplifies rear wheel removal, since the drivetrain remains mounted to the bike.

At its core is a proprietary 16-speed planetary gearbox located at the crankset, developed in collaboration with gearbox software specialists KISSsoft. It offers a wide 573% gear range with evenly spaced steps for consistent pedalling performance.

One of the standout features is the fully enclosed Gates Carbon Drive belt, integrated inside the chainstay. Belts are perfect for this setup: they don’t stretch, require no lubrication, operate quietly, and can last up to 30,000km – especially when shielded from dirt and moisture.

Shifting is controlled via levers on either side of the handlebar, similar to SRAM’s road and gravel systems. The current prototype is built into a full-carbon monocoque frame, with total bike weight projected between 10–12kg (22–26lb), making it one of the lightest gearbox-equipped bikes available.

Shimano Planetary Bicycle Gearbox

Shimano has recently filed a new gearbox patent that represents a major shift from its earlier derailleur-in-a-box concepts. This latest design introduces both eBike and non-eBike designs.

The internal layout reveals a large spur gear connected to a multi-stage planetary gear set featuring stepped gears. While the patent doesn’t specify the exact number of gears, it does outline gear ratio ranges between 250% and 444%.

One standout element is the offset between the crank and sprocket. This configuration could allow the gearbox to be rotated vertically, similar to the Effigear Original, giving full-suspension frame designers greater flexibility in tuning anti-squat performance.

Fox Factory Gearbox

And finally, there’s Fox Factory (renowned for their suspension systems), which has secured a patent for a gearbox design that tackles one of the biggest hurdles in gearbox tech: shifting under load.

Most gearboxes require a reduction in pedal force to shift gears, as attempting to shift while any pawls are engaged can cause damage. Fox’s solution involves a shift ring that automatically moves the pawls into a disengaged state under torque, allowing smooth gear changes even when the drivetrain is under load.

Although the patent doesn’t specify the number of gears, the compact layout resembles the Effigear Mimic, suggesting it could accommodate up to nine gears within its design.

Summary

I hope these new gearboxes sparked some excitement about the rapidly evolving world of drivetrain technology.

Let me know which design you like best and why. Also, if you come across any prototype gearbox drivetrains in development, feel free to share them in the YouTube comments. I’d love to explore and analyse their designs in future videos.

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The 2024 Pinion Gearbox Is A Derailleur Killer (Shift Under Load, No More Gripshift)

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The post 8 New Bicycle Gearbox Drivetrains For 2026 (Shimano, Praxis, RatioX, Fox, WRP) appeared first on CYCLINGABOUT.com.

But what happens if you ride a gravel bike, and prefer the ergonomics, lever feel, reliability and brake performance of Shimano GRX Di2? Can you wire a Pinion Smart Shift gearbox to Shimano GRX Di2 levers?

One CYCLINGABOUT reader was dissatisfied with his TRP Hywire levers. Patrick found that the brake master cylinder leaked droplets of hydraulic fluid that accumulated over time and ended up on his hands and handlebar.

Patrick decided to go on a journey to see if Shimano GRX Di2 shift levers would work instead. This was never going to be a straightforward task as Shimano uses proprietary plugs for their Di2 system. In other words, you can’t just connect the Shimano wires to the interface of a Pinion Smart Shift gearbox.

But Patrick still found a way to combine Shimano GRX Di2 levers with a Pinion Smart Shift gearbox! You can read his step-by-step tutorial HERE.

How To Wire Shimano GRX Di2 Levers To A Pinion Smart Shift Gearbox

Inside Shimano GRX RX815 levers are two shift buttons that connect to a small, round “function box”. This function box contains the interface electronics for the Di2 plug. For Patrick to make this hack work, the Pinion Smart Shift wires would need to be soldered directly to the wires inside this function box.

Patrick first removed the rubber cover of his right-hand GRX Di2 lever and untightened a small screw to gain access to the function box.

Next, he had to get inside the function box. A cap had been glued over the body of the box, so Patrick carefully cut through the glue until he could insert a spudger and pry off the cap. And there it was – the circuit board with the interface electronics.

Patrick pried up the circuit board to reveal three wires connected to the shift buttons. The wires were de-soldered and the Di2 cable was pulled from its hole. He then used a multimeter to confirm the shift buttons were wired up to function as expected. Yellow was “shift up”, purple was “shift down” and grey was a common wire that completes the electrical circuit.

To conveniently connect and disconnect the lever, Patrick purchased two 3-pin Higo Mini-X connectors/sockets. He soldered one of the cables to the function box and the other to the wire that originally came with the TRP levers.

The hardest bit was soldering the new wires to the existing wires inside the function box. The box is incredibly small and the cable lengths inside the box were very short. Patrick also had to remember to put heat shrink on the wires before soldering.

Once everything was soldered together, Patrick decided to fill the whole box with hot glue to seal it from humidity and protect the wiring from vibration. There was no need to re-fit the original cap as the box was now fully potted with glue.

And just like that, Patrick likely had the world’s first Pinion-compatible Di2 shifter!

Connecting The Levers and Gearbox

The last thing to solder was the other Higo connector to the Pinion Smart Shift cabling connecting to the gearbox. Patrick then added some heat shrink over the wires and hid them all in his downtube.

Currently, the shift buttons on the Shimano GRX RX815 right side lever are working fine and reliably. If Patrick wanted, he could connect the left lever in a similar way to be able to shift with both hands.

You can see more pictures and information about the Shimano GRX Di2 hack HERE.

• Bikes
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byAlee Denham

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The post How To Wire Shimano GRX Di2 Levers To A Pinion Smart Shift Gearbox appeared first on CYCLINGABOUT.com.

It took me some time to work out why it was built this way – and in this article, I’ll be explaining it all.

This highly unusual bicycle was built by one of the most well-renowned tandem builders in the world, Co-Motion Cycles. This North American manufacturer has been busy hand-building bikes since the 1980s, and I actually once commissioned them to build a fully belt-driven tandem that I rode from Europe to Australia.

Ok, so why has the Pinion gearbox been separated from the cranksets on this bicycle? To understand, we need to learn a bit about how both Pinion gearboxes and tandem bicycles work.

Let’s start with the Pinion gearbox.

Understanding Pinion Gearboxes

What you’re looking at is an 18-speed Pinion bicycle gearbox. This is not dissimilar to gearboxes found in other industries, in fact, the designers of this gearbox are former Porsche automotive engineers.

Compared to derailleurs, Pinion gearboxes are less susceptible to damage, they don’t require any tuning or adjustment, they don’t wear out, and you can change gears any time. There is very little cleaning too – the only maintenance is the 10,000km oil change which takes no more than 15 minutes to complete.

The thing you need to know about these gearboxes is that, unlike a normal drivetrain, the drive sprocket moves at a different speed to the crankset and the speed varies depending on the gear selected.

In the first gear, the cranks rotate almost twice as fast as the drive sprocket (1 to 0.55). And in the 18th gear, the sprocket rotates significantly faster than the cranks (1 to 3.45).

Ok, so the changing sprocket speed is the first thing you need to remember. Let’s now discuss tandem bicycles.

Understanding Tandem Bicycles

Tandems use a timing belt or chain that links up the pedal speed of the front and rear riders. The sprockets of a timing gear are usually the same size, which keeps the front and rear cyclists pedalling at the same RPM.

The advantage of pedalling in-phase is that it’s easier to take off from stationary, it’s great for balancing, and both sets of pedals can stay up high when cornering.

But it’s worth noting that some tandemists do like to have their cranks out of phase, which can help eliminate the ‘dead spot’ in the pedal stroke. By setting the crank arms 90 degrees out there will always be one rider in the power phase.

Why This Pinion Tandem Drivetrain Has Three Belts

Knowing that the Pinion drive sprocket rotates at different speeds in different gears, it’s clear we cannot just connect this sprocket to another crankset like normal.

If we did, one rider would be pedalling at a vastly different cadence.

To get around this, Co-Motion has installed a typical timing gear on the non-drive side of their Pinion tandem with a 1:1 ratio.

The combined power of the riders is then fed into the gearbox using the first drive side belt. This belt essentially replicates what a Pinion crank arm does – feeding pedal power into the gearbox for a change in gear ratio.

Our last belt then sends the pedal power from the gearbox to the rear wheel just like normal.

After cracking the code of this bizarre drivetrain, it left me wondering why we don’t just put the Pinion gearbox at the rear cyclist’s crankset, and mount a second timing sprocket to the crank axle?

It turned out I wasn’t the first person to have this thought…

Campmajo’s Pinion Tandem Solution

Spanish custom bicycle builder, Campmajo, has built a few tandems with a Pinion gearbox at the rear crankset.

Campmajo machines a special sprocket spider that clamps firmly to the crank axle so that it can rotate at the same speed as the Pinion cranks. This allows for a 1:1 timing gear with the second crankset.

The issue with this setup is that it requires the drive side crank arm to be machined down to make space for the spider. But Campmajo has assured me they’ve extensively tested their modification and are so confident of its strength that they provide a 5-year warranty on it. The great news is that Pinion will still honour the factory warranty on the rest.

One downside to Campmajo’s design is that it might not be wide enough to fit two belt sprockets. This then had me wondering if it was possible to move the timing sprocket to the other side of the gearbox axle, and lo and behold, someone had already thought of that too.

Belt Bikes’ Pinion Tandem Solution

Dutch bike manufacturer Belt Bikes have created their own tandem crank arms for Pinion gearboxes. This has allowed them to build a sprocket spider into the left crank arm for a belt drive timing gear.

This is a super neat solution, however, the downside is that the q-factor – or distance between the crank arms – has been increased by 40mm to accommodate the new spider. This change in dimension could potentially result in knee-related pain for some riders, but it’s worth noting this is still 25mm narrower than many fat bike cranksets.

Summary

What started as an article describing a quirky Pinion tandem drivetrain took me down a rabbit hole of bikes and products I never knew existed.

It’s cool to see the custom bike community finding ways to fit Pinion gearboxes on tandems. While Co-Motion’s triple belt drivetrain is an interesting solution to the problem, if it were me, I’d be opting for the more simplified Campmajo spider and modified crank arm, or Belt Bikes Pinion tandem crankset.

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The post Why This Weird Pinion Gearbox Bike Has Three Belts (Pinion Tandem) appeared first on CYCLINGABOUT.com.

For those who aren’t aware, the Rohloff Speedhub 500/14 is an internally geared rear hub that has been servicing the demands of bike travellers for a few decades now. Inside the oversized hub shell are 14 gears that offer a wider gear range than most derailleur drivetrains.

The gears all sit inside an oil bath that’s sealed away from the elements. These hubs work great when the riding conditions are good and even better when they are not!

Rohloff hubs are especially popular amongst bike travellers and commuters who ride year-round. This is because they are very low-maintenance (especially when combined with belt drive), easy to clean, and impervious to dirt, mud, salt, and snow.

But one downside to the Rohloff hub has always been the necessary twist shifter which can be slippery when wet and hard to twist if you have sweat, mud, or sun cream on your hand. The twist shifter is also less ideal for those with limited hand or wrist mobility as it requires a lot of grip strength.

In addition, this shifter has always been awkward to fit to a drop bar bike.

While many aftermarket solutions have become available over the years, everything comes with compromises to either the ergonomics of the shifter (awkward shifter location), shift performance (long lever throw) or reliability (added shifter complexity).

The neatest and most popular solution is the Gebla Rohbox which allows you to use modified SRAM or Campagnolo shifters with your Rohloff hub. That said, some dislike the long lever throw, and find it slow to change multiple gears in quick succession. Users have reported shifting glitches too.

Now we have a new aftermarket electronic shifting kit for Rohloff hubs that promises instant gear changes with very little effort, and neat integration with drop bar gravel bikes.

Let’s take a closer look at the SternShift system.

SternShift Electronic Shifting For Rohloff Hubs

This shifting kit comprises three main components:
– An electronics box that contains the battery and the control board
– A set of gear shifters at the handlebar
– A rear gear mech that attaches directly to the Rohloff hub

This shifting kit is not wireless like you might expect. The system is instead fully wired from the shifters to the Rohloff hub. There is, however, a quick-release cable attachment at the rear wheel for quick and easy removal.

Mechanical engineer Hans-Hermann Herms spent three years developing the SternShift electronic shifting system. Approximately 50% of his time was focused on the hardware, and 50% on the software.

Flat or Drop Bar Electronic Shifting

The SternShift electronic shifters are available for both flat bars and drop bars.

The flat bar shifter clamps to the handlebar in the typical location and offers thumb shifting with dedicated up and down buttons.

The drop bar shifters are extremely compact and are designed to be mounted to the curved areas of drop bars. They are intentionally separated from the levers so that you are not tied to any specific brand of brake lever. To change gears, you use the sides of your thumbs to change gears (see video below).

Pressing the shifter buttons briefly changes one gear at a time. You also have the option of pressing and holding the shifter for a double-gear shift.

Hub Dynamo Powered or Battery Powered

You can choose whether you want a dynamo-powered or battery-powered SternShift system.

The dynamo-powered version is the neatest and most convenient, as the hub constantly supplies power to a small battery at the handlebar. The battery itself is capable of between 600 and 1800 gear shifts and can be optionally charged from a power bank while you’re cycling too. The charge level of the battery is displayed in green, yellow and red via an LED at the rear gear mech.

The system can also be used without a dynamo hub, although this is much less convenient as it will require frequent charging from a battery bank.

Pressing the shift buttons for more than three seconds deactivates or activates charging. This could be useful if you have a separate USB charger wired into your dynamo setup, or if you want to send 100% of your dynamo power to some bright lights.

After 20 seconds of inactivity, the system switches to ‘sleep mode’ to save power. It will switch back on automatically when you move the bike or press a shift button.

If the gears are changed more than 20 times while stationary (presumedly by accident), the system can even switch to ‘protection mode’ until you start cycling again.

SternShift Stem or Electronics Box

The central element of SternShift is the electronics box, which contains the battery and the control board. It’s also the place where all of the cables come together.

You can hide these electronics inside a specially designed stem with ports for the three cables. The stem is currently only available in a 90mm length and it has a ±6° angle.

Alternatively, there is an electronics box that’s mounted underneath your handlebar. This water-resistant tube houses a larger battery that can make three times more shifts between charges – if you aren’t powering the system from a dynamo hub, you’ll likely want this option.

Does SternShift Require A Special Frame?

Unfortunately, it does. The frame must have the long, non-drive side Rohloff OEM dropout to anchor the rear gear mech. That means you cannot use SternShift on a Rohloff frame that relies on the disc brake mount for its torque anchoring.

Is The SternShift System Waterproof?

SternShift is protected against water splashes, but not against full submersion. It also cannot be cleaned with a high-power pressure washer.

Can The SternShift Change Gears Under Load?

SternShift will change your Rohloff gears quickly and precisely, but not with full pedal force.

It shifts the same as any Rohloff hub, which means that you must ease your pedal force for a fraction of a second to make gear changes.

How Much Does The SternShift System Cost?

The SternShift kit has just hit series production.

The retrofit kit is €799 and can be configured for dynamo or battery power, and drop or flat bars. If you want the electronic components hidden inside a specially designed stem, the kit price jumps to €949. You can also buy the SternShift stem by itself for €199.

And if you have particularly deep pockets, SternShift is available with all Rohloff gravel bikes from Falkenjagd and Rennstahl and can be ordered in the configurator.

For more information on this Rohloff hub electronic shifting kit, make sure to check out the SternShift website.

• Bicycle Drivetrains

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The post Electronic Shifting For Rohloff Hubs Is Now Possible Thanks To SternShift appeared first on CYCLINGABOUT.com.

Belts are clean, silent, and can last 3-4 times longer than chains. They also do not rust and do not require any grease or lubrication. This keeps bike maintenance to a minimum (just a splash of water will do) and ensures you never get black marks on your hands or pants again.

But belt drive systems have always relied on the use of a gearbox or internal gear hub to provide multiple gear ratios… until now.

The prototype multi-speed belt sprocket that we’re discussing today could be an internal gear hub killer, replacing the 2 and 3-speed models sold on millions of bikes each year. Veer Shift Drive aims to combine the efficiency and performance of derailleur gear systems with the durability and low maintenance of belt drives!

In this article, I’ll first explain how external belt shifting works. I’ll then compare Veer Shift Drive against internal gear hubs, we’ll take a look at the most suitable bikes for this drivetrain, and we’ll finish up with some frequently asked questions.

So, how does this crazy transforming sprocket work?

How Does Veer Shift Drive Work?

Veer Shift Drive places six rotating segments onto a typical freewheel at the rear hub. On each side of the segments is a different number of belt teeth.

When the rider initiates a shift, the segments flip one by one, allowing the belt to transition to the opposite side. By the time all six segments have rotated 180 degrees, the diameter of the sprocket will have changed – increasing or decreasing the gear ratio of the bike.

The segment rotations are driven by pedal force, which allows the segments to flip at a rate that perfectly matches the rider’s cadence. You’ll also notice the rotations are all completed in the zone that’s never in contact with the belt – this guarantees the sprocket is always locked in one gear or the other.

A tensioner takes up the belt slack and ensures the belt stays on, even over rough terrain.

Upon product launch, the up and downshifts will be made using a wireless shifter at the handlebar, but a cable-operated shifter will be available down the line.

Two-Speed Belt Drive Shifting

As far as I’m aware, this futuristic-looking drivetrain is the first two-speed belt sprocket for bicycles.

Instead of the belt shifting across the rear sprockets as we see on chain drive, this sprocket shifts underneath the belt. This is an important feature as belts must operate in a perfectly straight line.

The high gear is 1.4X larger than the low gear (140% gear range), which might not sound like a lot, but it can be all a bicycle needs in a flatter urban setting – especially if fitted to an electric bike.

You can think of the second gear as an ‘overdrive’ gear for high-speed cruising or a ‘bailout’ gear for climbing up hills. For reference, competing internal gear hubs have a range of 138 to 186%.

Shift Drive drops in place of a cassette (or a drive sprocket) on existing wheels. In fact, this drivetrain should be retrofittable to almost any bike, as the tensioner provides the appropriate belt tension, and the Veer belts can uniquely be split and installed on any bicycle frame.

External belt shifting could end up on the full gamut of bikes, including folding bikes, and even full suspension mountain bikes.

So, what are the main advantages of external belt shifting when compared to internal gear hubs?

Advantages of External Belt Shifting

Regarding functionality and cost, Shift Drive will compete with the 2 and 3-speed Shimano, Sturmey Archer and Bafang hubs found on urban and commuter bikes.

This drivetrain holds a surprising number of advantages over internal gear hubs.

To start, it’s a full kilogram lighter and can operate with a higher drive efficiency. This is because it engages fewer components than a gear hub – after all, planetary gear sets whir away inside hubs and generate friction.

With external belt shifting, you can shift under full power, and there won’t be a big clunk between gear changes. This is because the belt slowly transitions across the morphing sprockets, allowing for super smooth gear changes.

Unlike internal gear hubs, Shift Drive is compatible with rear hub motors found on the majority of eBikes around the world. This is a big deal as bikes with rear hub motors are currently limited to using either derailleur gears or expensive gearboxes. Shift Drive would bring low-cost shifting and belts to a new category of eBikes.

External belt shifting is compatible with mid-drive motors too, and it’s perhaps even more suitable than a gear hub as it can potentially handle more input torque.

And in the event of component failure, replacing a belt sprocket will be much easier than cutting an internal gear hub from a wheel, and re-building it onto a new rim.

The advantages of Shift Drive all sound pretty good. But it’s important to note that internal gear hubs have been refined on bicycles for over a century, so they will be a tough component to beat!

Let’s now understand why they are so great.

Advantages of Internal Gear Hub Shifting

Gear hubs have proven the test of time. They are affordable and reliable thanks to their enclosed design that protects the gears from the elements, extending the hub lifespan, and ensuring consistent performance.

Gear hubs require very little maintenance and you can shift gears anytime, including while stationary.

In addition, the shifting of most internal gear hubs is made using a reliable cable-activated mechanism. No batteries, electronic components, or wireless signals are required to make shifts, keeping things as simple as possible.

Right, what will it take for Shift Drive to beat internal gear hubs?

What Will It Take To Beat Internal Gear Hubs?

As Shift Drive is still in development, it will take a while before we know whether it’s high-performing, reliable, and long-lasting.

If Veer wants to go head-to-head with multi-speed hubs, here are some things they will need to perfect:

• The multi-speed belt sprockets need to last as long as regular belt sprockets.
• The rotating segments need to be packed with grease, and well-sealed so that they can freely rotate even with exposure to dust and debris.
• The belt needs to stay on the sprocket under high torque applications, as well as over rough terrain.
• The wireless shifter needs to be fast and accurate, with a user-friendly design.
• The tensioner needs to be durable and silent in operation.

If any of these things are not up to scratch, bike manufacturers will simply stick to tried and tested internal gear hubs.

Let’s now take a look at the types of bikes that will best suit Shift Drive.

What Kind of Bikes Are Suitable For Veer Shift Drive?

Budget Urban Bikes

Low-cost urban bikes are designed to be as low-maintenance and reliable as possible, so it makes sense to pair them with multi-speed belt drives. Bikes in this category include commuting bikes, folding bikes, rental bikes, and beach cruisers. The Priority bike range will give you a good idea of what these bikes look like, and how they are priced.

Mid Drive eBikes

Mid-Drive urban eBikes like the Yamaha B01 are another bike category that’s suitable for Shift Drive. Mid motors can take advantage of the lower gear ratio to provide more wheel torque up steep hills, allowing the motor to operate more efficiently, and increasing the overall range. Alternatively, bike manufacturers could leverage the lower gearing of Shift Drive to instead fit smaller, lighter and less powerful motors to their eBikes, which would allow for smaller batteries too.

Hub Drive eBikes

Shift Drive would also be suitable for hub drive eBikes from brands like Rose, Geos, and Urwahn. While the motor will not take advantage of the lower gearing on steep climbs, the rider will be more effective at helping the motor, which ultimately increases eBike range.

Bikes That Need More Gear Range

A niche application for Shift Drive could be to broaden the gear range of a gearbox drivetrain. Currently, those who are dissatisfied by the gear range of their gearbox or gear hub will usually fit a two or three-speed planetary gear crankset, but Shift Drive could be a lighter, cheaper and more efficient option.

Light Electric Vehicles

Veer has made it quite clear they want their products on more than just bicycles. Shift Drive could also end up on lightweight scooters, mopeds and all kinds of urban delivery vehicles.

Before I sum everything up, let’s go through some frequently asked questions to make sure you’re fully informed about this unique drivetrain.

Veer Shift Drive FAQs

How much will Veer Shift Drive cost?

If Veer wants this gear system to be competitive with internal gear hubs, the sprocket and tensioner will likely need to cost US $150 or less.

How much will Veer Shift Drive weigh?

The front sprocket, two-speed rear sprocket, belt, and tensioner total 570 grams. This means it’s about 50% heavier than *just* a chain, or around a kilogram lighter than an internal gear hub with a belt drivetrain.

What would happen if the rotating segments jammed?

If any of the rotating segments jam with debris, there is an internal clutch-like mechanism that will prevent the shift from occurring. The worst-case scenario is that you would be locked into one gear should you jam a segment.

What would happen if you stopped pedalling mid-shift?

The gear change would simply pause temporarily, and resume once you’ve started pedalling again – just like a derailleur.

Do the missing belt teeth in between the segments affect the performance?

There will undoubtedly be more flexing in the belt, but whether this translates to durability concerns or additional drive resistance, we simply don’t know yet.

Summary

Veer Shift Drive is a novel prototype that certainly shows a lot of promise.

Compared to internal gear hubs, Shift Drive could be lighter, more efficient, easily serviced or replaced, compatible with hub motors, shifted under full power, able to handle more input torque, and easily retrofittable to existing urban bikes.

If Veer wants this to be the drivetrain of choice on millions of urban bikes around the world, they will now have to prove Shift Drive is reliable and long-lasting.

Let’s wish them the best of luck.

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The post Are Chainless Belt Gears The Future of Bicycle Drivetrains? appeared first on CYCLINGABOUT.com.

Like other planetary gear hubs, the Kindernay promised a long-lasting drivetrain with less maintenance, zero gear adjustment, instant shifts, and components that are less susceptible to wear and damage.

The Kindernay 7 and 14-speed hubs had a few defining features:

• The gearboxes could be separated from the hub shell and you could move them between multiple wheelsets
• They used hydraulic trigger shifters
• They were designed specifically for 12mm thru-axles
• They were lighter than the competition (and only 400 grams heavier than a Shimano Deore derailleur setup!).
• They had a higher torque rating than other internal gear hubs
• They had a wider gear range than other internal gear hubs
  

Unfortunately, I’ve just heard some bad news from Kindernay…

The Kindernay Bankruptcy

The company behind Kindernay, CA Technology Systems, recently filed for bankruptcy according to an article on Shifter.no.

The trustee of the company is currently considering selling the assets and rights to the gear hubs. A date for a possible auction has not yet been set.

At this stage, aftersales support for existing Kindernay users is unknown. Hopefully, a large array of spare parts will be made available to a bicycle shop or distributor.

The Kindernay Void

It’s always sad to see a high-quality, niche cycling product disappear from the market. While not perfect, the Kindernay hubs had some appealing advantages over the competition.

Unlike most other internal gear hubs, these hubs were designed for mountain biking. The 7-speed hub added very little weight to a bike compared to a 1X drivetrain (300 grams extra unsprung mass), and the hydraulic trigger shifter was a welcome alternative to the grip shifters found with most internal gear hubs.

A defining feature was the Kindernay system’s modularity. This meant you could own one expensive gearbox that could be transferred between wheels. For example, you could leave the gearbox in your mountain bike year-round, but swap it into your fat bike in winter, or touring bike when you set out for your annual adventure.

These unique features will be missed.

What Are The Kindernay Hub Alternatives?

The closest internal gear hub currently is the Rohloff Speedhub. It has the same number of gears (14), a similar gear range (526% vs 543%), and almost identical gear steps (13.6% vs 13.9%).

After 25+ years of production, Rohloff hubs have an excellent track record for reliability and longevity. One owner has even cycled over 470,000km on one! These hubs have also been tested to have low frictional losses, which means the maximum amount of your pedal power will go toward driving you forward.

There are some other new internal gear hubs worth mentioning too.

The 3X3 Nine is a 9-speed hub that’s made in Germany and offers a choice between an electronic shifter and a regular grip shifter.

This hub has a bigger gear range (554%) and fewer gears than a Kindernay. This results in rather large gear steps of 23.8%, almost twice that of the Kindernay or Rohloff hubs.

Large gear steps like this are indicative that 3×3 is targetting the electric bike market. As e-bikes accelerate faster, it’s not uncommon to find yourself changing two or three gears at once on a typical drivetrain. Larger gear steps ultimately mean less shifting is required on eBikes, however, it also makes the hub less suitable for standard bikes as you might find yourself ‘in between gears’ more frequently.

Another indication that the hub is designed around eBikes is that it will handle 250Nm of input torque from a mid-drive motor. This is significantly more than both Kindernay (160Nm) and Rohloff (130Nm).

Interestingly, the 3×3 hub is lubricated with grease instead of oil. This lubrication choice has allowed 3×3 to reduce the hub maintenance. The grease change interval is a lengthy 25,000km, a figure five times further than the oil-change interval of a Rohloff hub (5000km).

Another fascinating German-made gear hub that’s available for pre-order is the Revolute Hub1.

This six-speed hub has been primarily designed around eBike use, so it too can handle 250Nm input torque. This hub has a narrower gear range (400%) than most gearboxes, and larger gear steps too (30%+).

An interesting feature of the Revolute hub is that it doesn’t spin backward! This means that when you stop on a hill, you do not need to pull your brakes to prevent the bike from rolling backward. This will be especially handy with heavily laden cargo bikes but could be nice on a regular bike too.

Lastly, don’t overlook the Shimano Alfine hubs.

These are notably quiet in operation, well-priced, and generally reliable. I really like the electronic shifting versions, which help to boost the reliability of the hub, and you can pair these hubs with the excellent Shimano Di2 drop bar shifters on a gravel or commuter bike.

Summary

The modular design of the Kindernay was nifty, the hubs were lightweight, and the hydraulic trigger shifter was a neat alternative to the usual grip shifter.

It’s sad to see Kindernay file for bankruptcy. I hope a sale of the assets and rights to the hub comes to fruition, and that the hubs can live on through another company.

Luckily for consumers, there are still a handful of other high-quality internal gear hubs available. For alternatives similar to Kindernay, I’d recommend looking into Rohloff, 3X3, Revolute, and Shimano Alfine hubs.

The post The Kindernay 14-Speed Gear Hub is No Longer (They Went Bankrupt) appeared first on CYCLINGABOUT.com.

But technology has come a very long way since the 1800s, especially when it comes to textiles – so, perhaps a rope, or “String Drive” bike is the ultimate solution?

In this article, I’ll introduce you to a very special chainless drivetrain that uses Dyneema ropes to propel you forward. These bikes were produced from 2011 to 2021 and used similar ropes to those found in fancy bicycle spokes, paragliding lines, sailing ropes, and even human-powered helicopters.

Here are some quick facts about String Drive to whet your palate: it’s completely grease and oil-free, it has 19 non-overlapping gears, you can change the gears while stationary, and the gears don’t ever require adjustment.

To prove that String Drive is no gimmick, Ferenc Szonyi (an ultra-endurance cyclist) used this drivetrain in the insane Race Across America, a non-stop 4,800 km cycling event (3000 mi). In just 11 days and 10 hours, the athlete on the String Bike completed the route. That’s a crazy 422 km (or 262 mi) per day!

Of course, there are downsides to a rope drivetrain too. So, let’s dive deep into the technology and determine if we will see ropes on bicycles again.

How Do String Drive Bicycles Work?

I know it looks crazy and complicated, but it’s actually rather simple in operation.

You pedal in a circular motion just like normal, however, instead of rotating a chainring, the crank arms move two levers that pull on ropes attached to either side of your rear wheel. The levers take it in turns to pull your wheel forward, with the ropes winding and unwinding neatly on the rear drums.

Incredibly, Dyneema ropes have a higher strength under tension than a bicycle chain.

A 3.5mm rope can handle over 16,700N of force, which is twice the industrial standard for bicycle chains (8000N). To put this into context, the best Tour de France sprinters don’t even hit a quarter of the tensile strength of these ropes. That’s pretty impressive considering these ropes float in water!

The gear ratios are changed by moving the front pulley up and down recesses in the lever arms. There are 19 gear options, where the highest gear is about three times larger than the smallest (304% range). This is equal to a traditional road bike drivetrain (53-39tT + 11-25T), or Shimano Alfine 8-speed internal gear hub.

You can choose between three rear drum sizes that can either give you lower gears for the hills, or higher gears for the flat.

The ropes typically last 1000 to 2000 kilometres, and as they don’t absorb water, they can be used in wet conditions and even snow. That said, grit significantly affects longevity, so while it can handle extreme conditions, it performs best when the conditions are good.

Let’s talk about advantages.

The Advantages of String Drive Bicycles

To start, this drivetrain runs smoothly and silently without any grease or oil. This virtually eliminates drivetrain maintenance, and means that you’ll never get grease on your hands or pants ever again.

Once set up, String Drive doesn’t require any gear adjustment, and the gears won’t ever skip when you change them. In fact, you can change gears any time with this drivetrain: that’s while stationary, while coasting down a hill, and even under a full pedal load.

There is also no rear derailleur to damage or bend out of whack, and while the lever arms are large and exposed, they sit high and out of harm’s way.

Interestingly, the advantages we’ve discussed so far are all shared with an internal gear system paired with a belt. Let’s now discuss the advantages exclusive to String Drive.

Firstly, the pedals automatically rest at the most favourable starting position, so you can just get on your bike and ride.

While most drivetrains wear out the front and rear sprockets, as well as the chain or belt, the only regular consumable on String Drive is the ropes, which are about $10 each. The spare ropes can be easily stored inside your seatpost, and anyone can change them in about five minutes without removing the rear wheel.

String Drive is also designed to minimise the ‘crank dead spot’. It does this by decreasing the gear ratio at the top and bottom of the pedal stroke, and increasing it when you can exert the most force. This provides torque to the rear wheel over a longer duration, which is said to be more efficient – it has the same effect as using an oval chainring on a chain drive bike.

When you remove the rear wheel, the entire drivetrain stays with the frame. This makes for easy wheel removal and it’s great for transport too – you can put the dirty wheels into bags, and the bike travels cleanly. The bike will also stand up by itself without its rear wheel fitted.

When these bikes were available, the price was quite reasonable. City bikes were just over €1000 (~US $1100), which was excellent considering that the frame and many of the high-quality components were manufactured in Europe.

The last advantage is that the gears are spaced very close together, which allows you to almost always find the perfect gear ratio. This is not dissimilar to the Enviolo hub we recently analysed. To illustrate just how close these gear ratios are, each step on an 11-21t cassette (1-tooth difference between each gear) is still 50% larger than what String Drive offers (7.5% vs 5%).

String Drive has shown some significant advantages, so what are the downsides?

The Disadvantages of String Drive Bicycles

One reason why String Drive never took off is that the drivetrain cannot be installed on any bike. Instead, a specially designed frame must be used – one with the right guides and attachments, and with notably wide dropouts to fit the two rear drums.

Not only did the frame need to be special, but almost all components and spare parts were exclusive to StringBike, making them hard to obtain.

The design of the drivetrain itself also made it a hard sell. This is because the left side drum occupied the same location as a disc brake rotor, which meant the drivetrain was only compatible with rim brakes. While rim brakes offer acceptable performance, disc brakes have become the industry standard – limiting the versatility of this drivetrain.

Modern drivetrains are ideally eBike compatible too. Unfortunately, there was no easy way to make a String Drive electric bike as the components occupied the same space as mid-drive and rear hub motors.

The Dyneema ropes also wore out quickly compared to other drive options. The best chains offer top-level performance for between 4000 and 7000km, while modern belts can last upwards of 30,000km (both with contamination). In comparison, Dyneema ropes only lasted 1000 or 2000km.

A grip shifter needed to be used to change gears on a String Bike. Some users found these shifters stiff to rotate, especially when they were wet. Grip shifters don’t integrate very neatly on drop bar bikes compared to modern brake/shift levers either.

As you need lever arms, ropes, and drums on both sides of the bike, there was a weight penalty of approximately one kilogram (2.2lbs) compared to a derailleur bicycle.

A String Drive bike was also likely less efficient than a chain drive bike. Converting from rotary motion to reciprocating motion, and then back to rotary motion is never particularly efficient, and additionally, this drivetrain has many sliding surfaces that generate friction.

That said, the drive efficiency might just be superior to a gearbox or internal gear hub. The fact that four amateur cyclists could average 33km/h for 24 hours on String Bikes (Hungaroring 24H race), or that an endurance cyclist could cover over 420km per day (in the RAAM) suggests that drivetrain losses are not unreasonable.

The String Drive gear range was also small by modern standards (304%). It worked fine for most urban environments, but it became a bit limited if you wanted to climb both steep hills and have the gears for high-speed cruising too. For context, most road bike drivetrains now offer a 450% gear range and off-road drivetrains regularly exceed 500%.

Why Didn’t String Drive Take Off?

With the pros and cons laid out, you should have an idea about why String Drive didn’t take off.

Ultimately, the proprietary frame and components made it a really difficult sell, as did the clunky grip shifter, additional weight, lower drive efficiency, and short wear life of the ropes.

Furthermore, String Drive didn’t come out at a great time. It was developed just as disc brakes were becoming standard on bicycles, right when electric bikes were turning into the largest area of growth in the bike industry, and just as belt drive and internal gear systems had finally become a suitable alternative to chains and derailleurs.

Let’s finish this article with some of String Drive’s interesting quirks.

Other Interesting String Bike Quirks

Firstly, you can pedal backward and the bike will move forward! This is because the levers will always pull the ropes, no matter the direction your pedals are moving.

You also have the opportunity to set different gear ratios for each crank arm by using different-sized rear drums. This could be useful for those with a leg injury, or for training up a leg with a muscular weakness.

The reduction in ‘crank dead spot’ is another fascinating quirk. As I previously mentioned, String Drive was designed to decrease the gear ratio at the top and bottom of the pedal stroke and increase it when you can exert the most force.

While this sounds like a genius idea, it’s actually inconclusive whether there is a biomechanical advantage to using an elliptical driving path. According to carefully controlled biomechanical studies, your ankle movement changes when you ride with non-circular chainrings, and this change in movement effectively cancels out any possible additional power generated at your knees and hips.

That said, some people prefer the ‘feel’ of non-circular chainrings, and others say that they notice less strain on their knees, so I think reducing the crank dead spot is still an idea worth pursuing.

Summary

I honestly thought String Drive was a bit silly when I began investigating it. But after analysing every aspect of its design, I’m actually really impressed. The entire drivetrain is well thought out, and I had no idea that Dyneema rope tensile strength was so high.

The ropes are clean, maintenance-free, cheap, and easy to replace. I can certainly see how the designers imagined their bicycle drivetrain revolution, but unfortunately, they did not anticipate just how important disc brakes, electric motors, gearboxes, and belts would be in the decades to come.

The post Are Chainless String Drive Bicycles a Genius or Terrible Idea? appeared first on CYCLINGABOUT.com.

The efficiency of a clean and lubricated derailleur drivetrain is usually upwards of 97%. This simply means that 97% of the power that you put into the pedals is going into driving your rear wheel, and the remaining 3% is lost to friction.

The drive efficiency varies with the lubricant used, the quality of the drivetrain components, how worn the components are, the front and rear sprocket sizes, the chain angle, the chainring tooth shapes, the chain link shape, the rear derailleur’s one-way clutch design, the jockey wheel sizes, the power output and cadence of a rider… and more! A combination of these variables is why we see frictional differences between 1X drivetrains and 2X drivetrains.

The drive efficiency also varies significantly depending on the chain ‘dirtiness’ where the type of grit, amount of grit, and amount of lubricant left all play a role.

With all of these abovementioned variables, knowing exactly how much a ‘dirty chain’ slows you down is an impossible task. However, the following data should give us a good idea.

Note: the cover photo is by Tim Bardsley-Smith from when I biked the Mawson Trail.

How Do We Determine Drivetrain Efficiency

The drive efficiency data that we will be discussing was collected about a decade ago by Friction Facts, an independent test lab. I’ve previously analysed Friction Facts data in my articles that looked at the efficiency of belt drivetrains (the most recent belt data is found HERE) and 1X vs. 2X drivetrains.

All tests were conducted using a special test rig with a chain tension simulating 250 watts of power output. The cadence was set to 90 RPM. Each chain was run for five minutes, with data captured at the end of each five-minute run. When the chains were installed and removed from the test rig, they always faced the same direction.

The test rig is accurate within +/- 0.02 watts, and system losses from the four ceramic bearings in the equipment have been subtracted from the final results.

The Efficiency of A Dirty Bicycle Chain – Test #1

In this first test, a perfectly clean chain with a light oil-based lubricant ran at 97.6% drive efficiency.

The efficiency dropped by 2.8% after a test period in the rain*, and it was 3.2% less efficient with some wet mud contamination. Once the mud contamination had dried, the efficiency had dropped to 92.8%, which means that almost 5% more of your pedal power is now being lost to the dirty drivetrain.

*Unfortunately, details about the test period duration or conditions were not made available.

The Efficiency of A Dirty Bicycle Chain – Test #2

Friction Facts conducted a different test using six participants at a bicycle race in Boulder, USA. The chains were tested both before and after the one-hour cyclocross race to determine their drive efficiency after grit exposure.

Three participants were given Ceramic Speed UFO V1-treated chains, which are coated with a hot wax that dries onto the chain and provides lubrication. The other three participants used more common light oil-lubricated chains.

After the race, Friction Facts found the wax-treated chains lost an average of 0.7% drive efficiency, while the oil-treated chains lost an average of 1.7%. The likely reason for the difference here is that the wax lubricant simply collects less grit and even provides a barrier to stop it from entering the chain links.

The Efficiency of an Unlubricated Chain Drivetrain

The noise of a bicycle chain is usually a good indicator that additional friction is being experienced. After all, chain links are metal-on-metal so they need some form of lubrication to run smoothly.

What happens to the drive efficiency when you have no lubricant left on your chain? I’m glad you asked.

For this test, six different chains were perfectly cleaned and applied with a light oil-based lube. When they were put on the test rig, the drive efficiency exceeded 97% in all cases.

Next, the six chains were stripped back to bare metal with an ultrasonic cleaner. The drive efficiency was re-tested and was found to be as low as 89.6% and as high as 92%.

When we average out the decreases in efficiency we find that 6% of your pedal power is being lost when you don’t have any chain lubricant left. Even a dry muddy chain with a bit of lubricant works better than a chain without any lube!

Try to remember this next time you’re dealing with a squeaky chain…

How Much Does A Dirty Chain Slow You Down?

Using Bike Calculator, we can now simulate the speed differences between a perfectly clean and lubricated chain, and a chain of varying ‘dirtiness’. I will be using the Friction Facts data from the first test, and an average of the data from the unlubricated chain test.

Let’s assume our rider, bike, and equipment weigh a total of 85kg (187lb). The rider is on a gravel bike with their hands in the brake hoods.

Simulated Average Speed On Flat Gravel Terrain (250-Watts):

Clean and Lubed – 31.38km/h
Rainy and Lubed – 30.99km/h – 1.2% Slower
Wet, Muddy and Lubed – 30.94km/h – 1.4% Slower
Dry, Muddy and Lubed – 30.71km/h – 2.1% Slower
No Lubricant – 30.53km/h – 2.7% Slower

The differences in cycling speed are perhaps not as large as you’d think. This is because wind resistance and tyre rolling resistance are usually the two biggest forces that you work against on a bicycle.

Depending on the chain ‘dirtiness’, the reduction in cycling speed works out to be between 1.2% and 2.1%. And using a chain with no lubricant at all makes the bike almost 3% slower!

As the Friction Facts lab test was conducted at a power output that’s higher than that of the average cyclist, let’s run a simulation at a more suitable power output of 150 watts.

Drivetrain friction reduces linearly according to data shown in the belt drive test. This has allowed me to estimate a 31% reduction in friction for each chain condition when we drop from a power output of 250-watts to 150-watts.

Simulated Average Speed On Flat Gravel Terrain (150-Watts):

Clean and Lubed – 24.75km/h
Rainy and Lubed – 24.36km/h – 1.6% Slower
Wet, Muddy, and Lubed – 24.30km/h – 1.8% Slower
Dry, Muddy, and Lubed – 24.07km/h – 2.7% Slower
No Lube or Contamination – 23.88km/h – 3.5% Slower

The differences in speed are a bit larger with a lower power output. This is mostly due to the reduction in wind resistance. We now see a speed reduction of 1.6% to 2.7%, depending on the chain condition. And your speed could be 3.5% slower if you forget to lube your chain!

Summary

This data shows that a dirty bicycle chain can be anything from 92.8% to 96.8% efficient (depending on the contamination) and this can reduce one’s cycling speed by approximately 1% to 3%.

We see bigger differences in cycling speed when we test the aerodynamics of different luggage setups and the rolling resistance of different tyres.

That said, keeping your chain clean and lubricated is not a difficult task. When your drivetrain is running well, you will not only go faster, but your bike will be quieter, and you will experience less wear on your drive components – saving you money.

The post How Much Does A Dirty Bicycle Chain Slow You Down? (Drive Efficiency Test) appeared first on CYCLINGABOUT.com.

If you are riding (or considering) a Pinion gearbox bike, your only shifter options for drop bar bikes have been the grip shifters provided by Pinion.

However, the ergonomics and performance of this shifter location are highly compromised. You need to move your right hand away from the brake hoods to complete all shifts, and you need a special handlebar to fit them.

In addition, the shifter can be slippery when wet and can be hard to twist if you have a bit of sweat, mud, or sun cream on your hand. The gearbox cables are also not hidden neatly under the bar tape as many would like.

The recent release of the new 2024 Pinion gearboxes (Smart Shift) ultimately allows for the best drop bar gearbox shifting possible. But this is not the perfect solution for everyone – there is a higher price, you have to keep the electronic shifter battery charged, and you cannot retrofit these electronic shifters to older Pinion gearboxes.

The New HILITE Hibox Shift Adapter

HILITE has found a mechanical solution that allows you to fit your favourite drop bar shifters to any Pinion C-Line gearbox bike.

By installing a new “shift adapter”, you change how the cables pull at the gearbox, matching the pull ratio of many standard drop bar shifters (with a minor internal modification). This allows existing Pinion C-Line gearbox users the option to upgrade their shifters, and I’m sure the product will be popular with bike builders too.

The shift adapter allows you to use Shimano GRX/105 shifters, SRAM Rival/Force/Red shifters, and various Campagnolo shifters too. The shifters can be paired with hydraulic brakes or mechanical brakes, depending on the model you choose.

In the future, you will also be able to pair SRAM and Shimano trigger shifters for mountain bikes too. But we’ll have to wait a bit longer for that upgrade kit.

How Well Does The Hibox Shift Adapter Work?

The Hibox shift adapter allows you to assign your right shifter for changing to higher gears, and your left shifter for changing to lower gears (or vice versa). This is typically how people set up the shifting of SRAM electronic groupsets.

The Hibox is not the fastest way to move through your gears – each press of the shift paddle is just one gear shift at the gearbox. If you would like something more responsive, you will want to look into the 2024 Pinion gearboxes with Smart Shift.

See a video of the Hibox shifters in action HERE.

The Shimano GRX brake hood ergonomics are some of the best around (in my opinion). The hood shape does a great job of distributing pressure over more of your hand, ensuring all-day comfort. The raised ribs on the hoods provide better grip in the rain when your gloves are wet and covered in grit. One-finger braking works out to be more effortless on the GRX shifters too.

How Much Does The Hibox Shift Adapter Cost?

The shift adapter is expensive due to the high-precision components and low production volumes. It comes in either a black or silver anodised finish and will start shipping in late October 2023.

Hibox Shift Adapter only – US $333 / 300CHF / €315
Shimano GRX RX600 + hydro brakes – US $1222 / 1100CHF / €1158
Shimano GRX RX800 + hydro brakes – US $1333 / 1200CHF / €1263
Shimano 105 + hydro brakes – $1244 / 1120CHF / €1179
SRAM Rival + mechanical brakes – US $733 / 660CHF / €695
SRAM Rival + hydro brakes – US $1144 / 1030CHF / €1084
SRAM Force + mechanical brakes – US $866 / 780CHF / €821
SRAM Force + hydro brakes – US $1255 / 1130CHF / €1190
SRAM Red + hydro brakes – US $1555 / 1400CHF / €1474

Complete HILITE Gravel Bikes

Alternatively, you can treat yourself to a complete HILITE gravel bike!

A complete titanium build with a 12-speed Pinion gearbox, Gates Carbon Drive, and Shimano GRX shifters starts at 8000CHF (US $8882).

As pictured, the bike tips the scales at 11.5kg/25lb. However, HILITE has some tricks up its sleeve to get their Pinion gravel bike under 10kg/22lb if you were to throw more money their way.

Get your hands on the Pinion Hibox shift adapter HERE.

The post You Can Now Use Shimano GRX Shifters With Pinion Gearboxes (Hibox Shift Adapter) appeared first on CYCLINGABOUT.com.