Bamabikeguy didn't address the gear reduction question. There is no gear reduction where the engine joins the mount, it is direct drive (through a centrifical clutch) to the small drive gear/pulley. Also the big ring that snaps on the spokes doesn't have teeth all the way around so it would be difficult to calculate the exact gear ratio.
Dr. J. said:
How many teeth are on the motor and wheel pulleys? I am trying to figure the gear ratio. Also, does GEBE use a gear reduction where the motor joins the mount or is it a direct (inline) fit?
Thanks guys for your replies. If I could find the working diameter of the drive sheave (on the motor) and the driven sheave (on the rear wheel) diameters, the ratio could be found. Would anyone have the measurements handy? I have an ongoing rear engine project and would like to find a place to start concerning gearing.
Also, can you take off from a dead stop without pedaling using the GEBE setup?
With a 12 tooth gear on the motor, that would be 296:12 or 24.6:1 gear ratio. That would give a theoretical absolute maximum top speed on a 26" wheel of:
8000 revolutions/minute * 26/24.6 inches/revolution * pi * 60 minutes/hour / 63360 inches/mile = 25.15 mph max speed. If the engine is at 7000 rpms then speed is only 22 MPH.
The GEBE site quotes top speeds for the 35cc robin-subaru with the 12 tooth at 27-28 MPH - how is this possible without revving the engine to 9000 RPMS?
As far as I can tell the GEBE does not have any freewheel so if you have the throttle on and you are going down a big hill wouldn't the engine brake you at max RPM and never let you go faster?