Rob English on NuVinci + Gates Carbon Belt


[EDITOR’S NOTE: A customer recently asked Bike Friday Head Designer Rob English about combining a NuVinci 360 hub with a Gates Carbon Belt Drive system. Previously Bike Friday did not offer that combination. Now we proudly can offer it. Here is what Rob had to say:]

We hadn’t previously offered the Gates Carbon Drive with the NuVinci, initially because of the availability of the proper cog and because the gearing ends up very low on the tikit’s 16-inch wheels.

However, it is actually not any worse than the 60×22 Alfine 8-speed. The NuVinci runs from a 0.5 reduction to a 1.8 overdrive. So with 60×24 drivetrain this gives 20 to 72 inches. Not ideal, but useable. I had a tikit with 53×18 and the 8-speed for a while, which gives 25 to 76 inches.

That was fine for around town on the flat. If we could persuade NuVinci/Gates to do a 20T sprocket at some point that would be ideal (24 to 86 inches). But the last time I spoke with them they were clear that it would only be a 24T.

I would say that if the gear ratios will work for you, then the Gates+Nuvinci would be a reliable, durable solution, and knowing that the cog is available we can certainly build it for you.

Best regards,

16 Responses

  1. 0.5 to 1.6 is only a span of 320% (1.6/0.5). My Air Friday with Rohloff hub (525% range, distributed in 14 gears at uniform 13% steppings) gives a range of approx 22 gear-inches up to a nice tall 115 gear-inches. Oh to have a Gates carbon drive….. drool, drool…. Roll-on Rohloff!!

  2. Correction: NuVinci => 1.8/.5 = 360%

    But that still doesn’t approach the 525% of the Air Friday’s 14-speed Rohloff hub which is such a sweet machine that it’s often hard to decide between the Air/Rohloff and the full-size LiteSpeed/Campy alternative….. Roll-on Rohloff !!

    1. From Rob English:
      Because the Rohloff is mostly underdrive (direct drive is gear 11), the gear range you have now can’t be matched. With 60×20 (the biggest Gates gear ratio) on 406 wheels the Rohloff gives 16″ to 84″. Plus, of course, we don’t currently have a 20″ bike that will accept the belt drive, and on the tikit with 16″ wheels the range drops to 13″ to 70″.

  3. That doesn’t look such a bad range of gearing for a hilly commute. What we’re looking for now is a Gates/Rohloff set-up on a New World Tourist. It’s a design problem that needs to be solved.Go to it! If you can manage it I’m up for two next year.

      This issue with the 20-inch wheeled Pocket bikes is having a unified rear triangle for the belt, but then still enabling the bike to fit in the suitcase without removing the rear wheel. There just isn’t room! Alan and I have been discussing possible new designs to achieve all the goals, but I can’t put a timeline on when development will go further.

      1. I suppose Bike Friday’s philosophy is that every bike should pack easily for travel. But we only travel with our BF tandem. We use Pocket bikes for commuting because they’re nimble, compact, lightweight, and high performance, and you can throw them in a trunk if you have a flat or mechanical breakdown. For non-tikit commuters, carbon drive would be great, and we’d be willing to accept compromises on packability and folding speed. I can understand if that’s too far out of the BF mainstream, though.

      Currently the belt drive is only available on the tikit. To retrofit on a currently owned frame would require at minimum a new rear triangle, plus the rear hub, wheel rebuild and the belt drive parts. It may be a better option to trade in an older tikit and get a completely new belt drive NuVinci bike.

  4. You write:

    This issue with the 20-inch wheeled Pocket bikes is having a unified rear triangle for the belt, but then still enabling the bike to fit in the suitcase without removing the rear wheel. There just isn’t room!

    I have an Air Friday, and packing it in a suitcase has always required removing the rear wheel. So why is this a big deal? Fixing a puncture also requires removing the wheel. It has to be easy … is that the design problem?

  5. I’m also used to packing an Air Friday so as long as there’s a way of dropping the wheel out and re-tensioning on replacing it, packing into the case would be no extra hassle. However, I do use the quick fold + beam removal when packing into a soft bag for train travel. I guess the quick fold would be less quick but if the other design problem (removal and re-tensioning) was solved (presumably an eccentric bottom bracket and/or re-designed dropouts won’t work, I could cope with the extra inconvenience in order to have Rohloff and Gates. And as I get older that 16 inch gear is looking attractive.

  6. Hi, clearly I’ll have to wait for my next Friday to get a belt. Right now, if I’m stuck with a chain, I was wondering if you have any nuvinci built up wheels I can buy to replace my Sachs 3×7 wheel on my circa 1999 bike. I would likely have to get an eccentric BB or a single speed conversion chain tensioner. Have you guys been involved in such a project?
    — David

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