biopace orientation for a bent
Originally Posted by bikebob
Try contacting Gardner Martin at Easy Racers. On the plans from Mr. Martin for building a clone (since lost) there was a different orientation recommended.
As nobody else saw differently, I installed the ring about 4 weeks ago with the same chainring-pedal orientation as an upright. After your post, I diagrammed it and see any chainring orientation difference for a bent relative the upright should be relative the difference in cyclist leg angle change between the two bike types minus any change in the chain attack angle as it enters the top of the chainring for the two bike styles. Both those figures will change for each specific bent, and the Biopace design would have been for standing riders, seated riders or a compromise position.
On the Martin plans, were your talking about the Gold Rush streamliner or another model? Do you known if the Gold Rush in the Smithsonian has Biopace rings?
Do you recall if it was a small angle change on the plans you saw?
Anybody know if the proper upright Biopace orientation was designed for a seated rider or a standing rider or a compromise of the two?
Upon analysis, it looks as if my installed chainring (on cranks by its lonesome) is off about 20-40 degrees depending on which upright rider position the chainrings were designed for-my Biopace max effect points lagging since my seat angle differs more than my chainline angle from the upright bike angles.