On Friday, April 21, 2017 at 8:33:54 AM UTC-7, Frank Krygowski wrote:
On 4/21/2017 11:08 AM, wrote:


I had started this because in a recumbent the chain run is so long that it can't possibly be very efficient.

I don't know of any reason that a long chain should be much less
efficient than a short one.

Chain inefficiencies (small as they are) come from the friction as the
links bend around sprockets, and friction as rollers roll on and off
sprocket teeth. Some of the bending friction is between side plates
exacerbated by lateral angles, and long chain runs tend to have smaller
lateral angles. They may be more efficient than short chains.

--
- Frank Krygowski

Long chains have several guide pulleys along their length and each one of those pulleys absorb about a watt each.