Hand Ergometer

[mekanik]

Hi M8
Just been having a look @ your project and although you have expended considerable man hours on the prototype, i was wondering if you had given any consideration to using a Shimano/sram geared rear hub ?
Just a thought.
Take care and i sincerely hope your circumstances improve in the near future.
Regards
Mike

[irving2008]

Hi M8
Just been having a look @ your project and although you have expended considerable man hours on the prototype, i was wondering if you had given any consideration to using a Shimano/sram geared rear hub ?
Just a thought.
Take care and i sincerely hope your circumstances improve in the near future.
Regards
Mike

Mike,
Great minds etc... it was one of my first ideas. Sadly the maximum ratio on a Nexus hub is 1.5:1 and I need at least 3:1, plus the hub is too wide @ 110mm

regards,
Irving...

[mekanik]

Would the ring gears on the e-bay links not be better than plastic ?
those listed are cheap enough.
Could you use two spur gears with the correct ratio ?

[irving2008]

Would the ring gears on the e-bay links not be better than plastic ?
those listed are cheap enough.
Could you use two spur gears with the correct ratio ?

Epicyclic gears have very specific relationships. To get 3:1 the number of teeth on the ring is 2 x teeth on planet + 1 x teeth on sun gear. Without knowing the number of teeth, circular pitch and tooth form of the Nexus ring gear the chances of finding other gears to suit off the shelf is diminishingly small...