Choosing between modern bicycle drivetrains - Part three: The Gearbox

February 11, 2025

 In parts one and two, we explained that on a bicycle “transmission” literally means a way to transmit your power from the pedaling motion of your legs to the rotation of the rear wheel, propelling you forward. In other words, even a single speed bicycle has a simple transmission. Part one took an in-depth look at derailleur systems and part two addressed internally geared hub transmissions.

You probably know that there are more viable bicycle transmission options today than ever before, and that can make your next bike purchase confusing.  We’re putting forth an effort in this series to help you make an informed choice.  We’ve sorted the essential transmission types into 3 groups, and we’re presenting pros and cons for each type.

Gearbox Transmissions

While gearbox transmissions first appeared on bicycles a a century ago,  the innovative new Pinion Gearbox from Germany has created a quite a stir. Pinion offers a broad range of gearboxes, some with gearing range that surpasses that of derailleur systems, with up to 636% range from the lowest gear to the highest.

Like a hub transmission, a gearbox doesn’t show its complexity, as the bicycle chain (or belt) is driven by a single front chainring and a single sprocket at the hub. Inside, it’s more like an automobile transmission than the more complex planetary geared hub transmissions. In fact, the Pinion gearbox was designed by a former Porsche engineer.

Although Pinion is relatively new (production began in 2010 after 3 years testing in the field), their gearboxes have been very well received and have tested well in every application they’ve been used for. As a result, Pinion too is building an impressive record of performance and reliability.

And how about that gear range? It is remarkable. As an example, one of our Americano Pinion touring bike, equipped with the Pinion P.18 gearbox, has a low gear of 17” and a high gear of 107”, a total range of 636% while its derailleur-equipped equivalent has a low gear of 20.6” and a high gear of 117.9”, a total range of 572%. It’s an incredible feat that has ignited the entire industry, and turned on bicycle adventurers seeking broader gearing range with enviable performance. Gear inches, explained

Gearbox Transmission pros and cons

Pros:

1. When operating optimally, the Pinion gearbox transmission system is approximately 99% as efficient as a derailleur transmission. Because it requires far less maintenance, it is less likely to operate sub-optimally.
2. Shifting is easy, self-explanatory and linear. You can shift from gear 1 to gear 2 in one click, or jump from the highest gear to the lowest or any gear in between with a simple twist of the shifter to the indicated gear. You can do this while pedaling (with a slight easing of pedal pressure), while coasting, or at a complete standstill. That’s a great convenience when you’re touring, just came to a stop at the bottom of a steep grade, and are suddenly faced with a steep climb.
3. Although they can be set up with chain, we include the Gates Carbon Drive belts on all of our hub and gearbox transmission models (we discussed hub transmissions in part 2). These belts outlast chain by many times, never require lubrication, and run efficiently in all conditions.
4. Like a hub transmission, the inner workings of the Pinion gearbox are neatly enclosed in a sealed system, where they’re less vulnerable to weather conditions, dirt, dust or foreign objects causing problems.
5. Unlike a hub transmission, your gearbox is not part of your wheel and is therefore more secure against theft. Since the gearbox only works on a frame designed and built for its inclusion, it’s useless to most thieves.
6. Since the gearbox is centrally located, a Pinion-equipped bike is nicely balanced and does not feel “tail-heavy”, making it easier to move over technical terrain.
7. Having the gearbox located in the frame’s center/bottom bracket area means you can take advantage of any number of excellent single-speed wheels. Want to have a light & fast road wheelset ready to go for today, and a 29” x 2” or 27.5” x 2.6” wheelset tomorrow? Great! You can fit them all onto our Divide Pinion, for example. With disc brakes and lots of clearance, capabilities are enormous. All of Co-Motion’s Pinion-equipped bikes are spec’d with proven thru-axle wheelsets.

Cons:

1. Because the inner workings of the gearbox transmission are neatly enclosed in a sealed system, they require a high degree of technical skill to repair. Although regular maintenance is easy, in the rare instance when repair becomes necessary, it can mean you need to send your gearbox off to the nearest warranty center. Pinion is establishing or has established warranty centers on every continent but Antarctica.
2. Gates drive belts are not as commonly available as bicycle chain, so if traveling extensively in remote locations, we recommend that you carry a spare belt.
3. A gearbox is a little heavier than a 3 x 10 derailleur system, but getting very competitive, with Pinion’s new magnesium gearbox case, as used on the C.12 gearbox, an excellent choice for a lightweight adventure bike like our Klatch Pinion model.

That sums up our 3-part article series on drivetrain options here at Co-Motion Cycles. As you browse our website for your perfect bike, you'll see what drivetrains are offered in the listed specs as well as pricing for each in the upper right hand corner of each bike page. We're happy to be considered a pioneer in bringing a broader array of drivetrain choices to North American cyclists and proud of the fact that we've worked diligently to make each bike not only function, but to really shine in the way we've integrated each system.

Thanks for reading, and please let us know if we can answer any questions for you.

Dwan Shepard

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