Yes FB. Several hundred people shared it and then some road worker found it close to a road, abandoned with the chain disengaged. (pedalchain)
In this case it is pretty clear that the thief was some drunk guy coming home from a party saturday night and had a long way home. Then dumped the bike when the chain disengaged. No harm to the bike.
The battery "briefcase" was not on the bike so it had to be pedaled manually. Which is quite tedious work as it only have one high gear.
The centrifugal clutch is of this type:
http://www.kartbuilding.net/PlAnS/centrifugal_clutches_overview.jpg
The inside of it consists of 6segments if i recall. There are no pivotpoints for them, they just lay in there with a spring that goes around them all in a groove. Holding them together.
In the picture you can see the backside of the clutch where the plate in bent in between the segments at 3 spots to make sure they dont rotate with the bell.
I changed the stock spring, which was very stiff, to a spring that basically only can hold the segments' own weight. So engagement starts from close to 0 rpm.
Bad sketch to clarify.
This particular clutch would need heavier segments for this application tho, as the clutch will slip alot under 25km/h. And acceleration is pretty weak.
Above 25km/h it will have grip enough to alter the motors rpm for a 1-1 connection. (This is with the current limitation of 30A i use)
The large amount of slipping also means metallic dust that is bad for the motor.
I have had better results with centrifugal clutches on higher revving smaller motors.
This motor is a 49kV revolt 100 old model. At 12s it wont see much more than maybe 2300 rpm (at full charge), and the clutch with the stock spring is meant to engage close to 2000rpm if i recall correctly.
More commonly ised on IC engines that rev alot more.
So to sum up, a centrifugal clutch is awesome when setup right,.but it only provides a crucial function if the motor used is too weak to handle startup torque required.
seriously
