March 20, 2012
[EDITOR'S NOTE: The bell has rung, it's time again to take your seats and listen up as Bike Friday Head Designer Rob English holds class. Today's topic springs from a interested Bike Friday customer who wants to know why he can't combine the Gates Belt Drive technology on the Carbon Drive tikit with a NuVinci hub. Rob, take it away:]
Hi Michael, We haven't yet offered the Gates Carbon Drive with the Nuvinci 360 hub.
Initially it was because the date of the cog's available kept getting pushed back (although it sounds like, after over a year, it is finally done!). Secondly it was because the gearing ends up very low on the tikit's 16-inch wheels.
However, in review it is actually not any worse than the 60x22 Alfine 8-speed. The Nuvinci runs from a 0.5 reduction to a 1.8 overdrive. So with 60x24 drivetrain this gives 20 to 72 inches.
It's not ideal, but useable (I had a tikit with 53x18 and the 8-speed for a while -- which gives 25 to 76 inches. This 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. The Future's tikit has 80x25, which gives 27 to 83 inches on the 8-speed hub. I don't yet have enough miles on that c-drive belt to give a good opinion compared to the Gates (on which I have 7000+ miles), but it is definitely aimed at the recreational rider as opposed to the performance rider with the Gates.
We are using it for a clear reason -- to give customers a lower priced entry point for a belt driven bike, the frame of which will support an upgrade to a Gates system in the future if desired. Incidentally, shortly all our Gates bikes will be center-track. 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.
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