It’s one thing getting the chain timing right on a tandem. It’s a whole ‘nother challenge when you’re putting the shifting in the middle of it, rather than running a traditional cassette and derailleur. But Co-Motion figured it out for this stellar NAHBS show bike, which combines Gates Belt Drive with a Pinion gear box. And while Co-Motion didn’t use it, Cinq was showing off a better way to control internal gear box and hubs from multiple brands…

CoMotion belt drive tandem bicycle with pinion gear box

One would imagine there are enough things going on when off-road touring in tandem, so reducing drivetrain worries seems like a good idea. But to pull off the gear box with belt drive, Co-Motion had to rework the order in which things transfer to one another.

CoMotion belt drive tandem bicycle with pinion gear box

On the (rider’s) left side of the bike is the timing belt, keeping both riders pedaling in sync.

CoMotion belt drive tandem bicycle with pinion gear box

On the right is where the magic happens. Both riders’ output is sent to the gear box on the outer belt, which replaces the crank arm in a traditional setup. The inner cog is where it would be normally and is the one that sends power to the back wheel. It’s all controlled up front with a customized twist shifter on the bar.

Co-Motion Steelhead tandem gravel bike

They were also showing off this new Steelhead tandem all-road/gravel bike, which made room for larger WTB tires.

The frame is made with butted Reynolds still tubing and can be ordered in custom geometry and sizing, with your choice of a traditional welded construction or this fillet brazed version for a slight upcharge. The carbon fork is new, too, offering wider clearance and boost axle spacing. Check them out a

CINQ drops new shifters for internal geared boxes, hubs

 drop bar shifter adapter for pinion gear box shifting on bikes

One of the issues with Pinion’s internal gear boxes is the shifters…they need to have dual cable routing to work well (with many models, but not all). One cable pulls in each direction, moving things where they need to be. Which means you end up with oversized single-unit shifters like what’s shown on the Co-Motion bikes.

 drop bar shifter adapter for pinion gear box shifting on bikes

Cinq has been working on a solution to make the shifters more ergonomic and familiar, and now they’re ready to launch with both drop bar and flat bar versions. The kits are on Kickstarter now, here’s the video:

drop bar shifter adapter for pinion gear box shifting on bikes

Two models will be available, the Shift:R Road uses drop bar levers with integrated hydraulic brake master cylinders and lines from TRP, and the Shift:R Tour with individual thumb shifter paddles. Both will replace part of the mechanism on the Pinion gear box with a Cinq attachment to make it all work.

cinq flat bar shifter adapter for pinion internal hub shifting on bikes

The Pinion flat bar shifters will look like these, which are their version for Rohloff internally geared hubs. So, even if you don’t run the gear box, you’ve got options for better shifters. Check them out at


  1. Why couldn’t Co-Motion just place the Pinion at the stoker’s BB, and run a timing belt on the left like a traditional tandem?

      • presumably they could have opted for the C line of pinions gearboxes, they have a reduced q factor relative to the P line that i believe is pictured here.
        I agree that i would much rather see the gearbox located somewhere it is less likely by some rocks in the trail. They are not cheap pieces of equipment.

    • Presumably because it was more troublesome to integrate a left side timing sprocket into the crank, since only the splined spindle is exposed on that side of the Pinion. Q-factor would probably get unmanageable at that point as well.

      This solution is pretty clever, albeit complex and likely monstrously expensive. Even after the gearbox cost, that’s several hundred dollars of belts and sprockets — with three independent tensionings required for setup, and a lot of precise beltline widths to get right. Practical or not, it’s a fun design challenge and impressive show bike!

      • This ^^^^ would be the correct reason. The RHS cannot run a dual-belt-ring with the crank; the clamp-on LHS crank of the pinion will not support a belt-ring. Same applies for chain-drives. Pinion would need to redesign the whole gear-box for tandems, something that a small producer is unlikely to do for the micro-market of gear-hub tandem riders.

  2. This is really one of my favorite things I saw at NAHBS (as well as Hunter Cycles new min stem rack thingies). While all the stats of what builders are doing what across the board is neat and all, it’s this kind of innovation from smaller builders is what I feel is the real beauty of NAHBS and the handbuilt scene. The kind of ideas that could get killed in meetings at bigger companies, and even if someone did it’d take years before we’d even hear mention of it…if it’d happen at all.

    Builders and the companies like Cinq and pinion that support their ideas that are then resulted in brilliant execution like this is what I think is the best part about this scene. It’s innovation and purpose all while looking fantastic.

    And note, I do love seeing the stats I what the trends are at the show. Not dogging that, just I really enjoy this aspect to no end.

  3. I would love to know what actually shifts fastest, (less pedal revolutions). Would it be derailleurs, IGH, gear boxes, etc ? The gear boxes are intriguing. If weight is comparable I can see it being viable.

    • Rohloff’s shift faster than a derailleur system on the downshift (except for the 8—>7 shift.), and about the same on upshifts.

  4. Cinq shifters would be a huge improvement. The small amount of tandem riding I’ve done taught me that you are shifting all the time on a tandem, so brifters are a must.

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