Originally Posted by
Duragrouch
Yes, but if you have the money for a Rohloff, or even better, a Pinion drive system, money is no object.
And belts are quiet. I'm a retired engineer and I can't believe your efficiency numbers, I think that may be chains compared to V-BELTS which have significant friction losses (EDIT: They are comparing cogged belts to a fixed gear (cog) with chain, no derailleur); Cogged belts, especially narrow, Kevlar-core ones, are quite efficient, perhaps even superior to chains that have to run tight bends around small cogs and through the durailleur. Internal Gear Hubs have greater efficiency loss, on the order of 5-7% when not in the one direct-drive gear. The Pinion system may be better, but more expensive than my car, and requires a special-built frame. My only gripe about belts is that they require a frame with no chainstays or a break in them to be able to use a belt.
Right. I was reading an article regarding a Gates Carbon Drive vs chain and thete was a cross over point where below which a chain is more efficient, above which a belt won. The results did have some variability with tension. Of course, this is different than a v-belt whose mode of operation
is friction on an inclined plane.
As far as the Rolhoff, it does take a few percent of efficiency loss compared to a conventional chain/derailleur system. Noticably more loss in the lower ratios. 1st, 2nd, 3rd gear definitely feel like there is a bunch of things engaged inside combining for a "draggy" feel. They do get better as things break-in though. A couple of watts
(like, under 10 at speed) is well worth the trade off for other considerations.