Originally Posted by
tatfiend
PaulRivers;
I agree that the Uptown 8 is the only bike I am aware of with a full chaincase except for the Chinese and Indian utility cycles which weigh a ton and some Pashley models. Never been able to figure out why the American importers/distributors of commuter bikes do not spec them with full chaincases. The cases have to be available to them as similar bikes for the European market, also from Taiwan or China, have them fitted.
IMO all chain drive utility bikes fitted with gear hubs should include a well designed full chaincase.
The figures I have seen for shaft drive bikes indicate a approximately 2.5% power loss for each bevel gear pair. True when introduced over 100 years ago and still true today so far as I know.
The only reason I can think of is that perhaps adding a full chaincase makes it more complicated to get the rear wheel off if you get a flat. Plus, honestly, they can make the bike look kind silly if they're the big one like on the Uptown 8.
Being that an ideally maintained derailleur only claims to be 98% efficient, I highly highly doubt a shaft drive bike is anywhere near that. Also, other people on this forum have posted experiences with shaft driven bikes and talked about feeling a noticeable loss of efficiency for a shaft drive - I don't think 2.5% power loss has any basis in reality. Whether it's enough of a loss to matter to you is another matter - my internal gear hub is slightly less efficient than a derailler, but it's lower maintenance and better reliability (no frozen gears) for winter riding is by far worth it for me. Personally, I'd be very hesitant to get a shaft drive for efficiency reasons, but personally I cannot imagine buying a BMX bike either. :-)