Originally Posted by
Kimmo
Well, it's getting a little further
towards a CVT, but as my detractors will tell you, a human can be reasonably efficient over a range of RPM, and it's a pretty safe bet that it's impossible to engineer a CVT for a bike that doesn't have mechanical losses far in excess of any gains it makes...
So my detractors and I just differ over the range of RPM we're prepared to tolerate... +/- 1.75RPM over 30km/h sounds pretty good to me.
RPM vs km/h, red: 53/39x12-23, blue: my setup
One way to think about the graph - how tall is the next step in a staircase, when the higher you go, the harder it is to climb.
You kind of have to get on top of each gear as you shift up; I don't want to shift further, the higher I shift.
Well the beauty of it is (to me anyway) The electromechanics are the "hard" part, the user can decide what their goals are :-). The thing could be tied into GPS so all the rider has to do is thrash in the drops and is always in the gear they choose in advance for any section of a pre determined route :-).......and you could even have a "trim" that allows to back off or become more aggressive in that pre determined gearing.
I think it is a slick idea :-). You might even get an endorsement from the Amish because it no doubt runs on batteries :-)
Bill