In article said:Chalo said:The central problem of power assist is the same as that of human power:
it is in short supply. Variable gearing helps make the most of a small
amount of available power, and when all else is equal, it is preferable
to a single ratio....the only argument for a single gear ratio that seems to apply
to a gas motor is that of mechanical simplicity.
Werehatrack said:Simplicity, weight and cost, actually, but I didn't mention weight and
cost in the original post because the subject of a motor/gearbox power
unit wasn't what had been posited. The OP had advocated using a, IC
motor driving a der system. I've seen this tried several times; it
self-destructs in short order.
Ok, apart from the 'self destruct', what geometries have you seen ?
The 1 hp often advertised, seems absurd. As stated the engine power
should be half of an athelete's; so that you can get athelete's performance
from a relaxed pace. Then also the drive-train forces don't exceed
design.
Quoted message said:Electric drive through a der can be
done, but as you correctly pointed out, it's a poor plan. Electric
motors work best when they run at rated load and speed, and having the
der available would put the motor speed and loading out of the control
of the engineer and into the hands of the rider; range and motor life
reduction due to the rider's attempts to max out the motor's
capability would, as you posit, surely result.
If electric motors have restricted speed range, all the more reason for
gearing.
Quoted message said:I still hold that if a motorcycle is the desired result, then that's
what should be built; common bicycles are designed for human power,
and adapt poorly to having engines added. Power augmentation from a
battery and electric motor is more easily retrofitted, and far cleaner
as well. Its sole current disadvantage is lack of support in
infrastrucure; there's almost never a place to recharge at your
destination, so range is severely limited. Gas engines, although
nearly unlimited in range, have more adaptation problems, and with the
ones presently available, are high in pollution.
--
The question was NOT about pollution. Read the subject again ;-) ,
how to mount the engine to:
* use the existing pedal gearing,
* achieve gearing down from the motor,
* achieve 'disengaging' of motor.
Thanks for info .
== Chris Glur.