Internal Gear BB (not retro)

[Rob1]

THIS is the future of gear-shifting: http://www.nostalgiacentral.com/images_pop/Image-31_2.JPG

 

[DM]

Re: sealed drive

...the only downside to it is that a chain is 98 percent efficient while planetary gearsets like the Rohloff or the Nexus are rated at about 94 percent efficient. I am not sure of the energy loss associated with the Schlumpf BB...

Yeah, using 2 planetary gears is going to have SOME effect on drivetrain efficiency.

But if you used one of the two "overdrive" versions of the Schlumpf (as opposed to the version that LOWERS the standard gearing) I doubt you'd be too bothered about the slight drag when the BB is engaged for the downhills.

 

[Err]

People often quote 98.67% efficiency for a chain drive

Surely this is based on clean, lubed, new chain, tall teeth etc. Does it include being run thru a rear derailer or is it really based on a track setup.

How does efficiency change with chain angle, tooth wear, dirt mud etc, adding a rear derailer etc?

thanks for all the links pics info.

 

[yo-eddy]

Rohloff themselves say this....
http://www.rohloff.de/en/technical/effi ... index.html