Originally Posted by
PaulRivers
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. :-)
2.5% per gear pair is 5% for the shaft drive plus any losses from the gear hub. The 98% efficiency for derailleurs often claimed is not accurate either as they vary depending on the gear selection even on a well maintained and adjusted derailleur system. Interesting tests of gear hub and derailleur efficiencies were done some years ago by Chester Kyle and Frank Berto and written up in the IHPVA Journal, available for download.
IMO a properly designed chain case should not interfere with rear wheel removal. Note the "properly designed" qualifier. A full chaincase only looks silly to those who are not used to seeing bikes with them. Many Europeans look at American commuter/city bikes and think they look ridiculous due to the lack of chain protection and standard generator lighting. The Breezer appears to me to be a truly practical city or commuter bike, one of very few available here.
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Gear Hubs Owned: Rohloff disc brake, SRAM iM9 disc brake, SRAM P5 freewheel, Sachs Torpedo 3 speed freewheel, NuVinci CVT, Shimano Alfine SG S-501, Sturmey Archer S5-2 Alloy. Other: 83 Colnago Super Record, Univega Via De Oro
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