pbeggs
Member
I installed a sick bike parts freewheeling crankset on my 80 cc, 1960's murray beachcrusier with homebuilt jackshaft,... geared it down some,..
11 tooth engine spr.
30 tooth jackshaft input spr.
10 tooth jackshaft output spr
48 tooth crank input
30 tooth crank output
25 tooth rear hub spr.
this gives me about 90 rpm @ the crankset @ 5000 rpm on the motor
the result is a bike that will climb (accelerate up actually) a steep hill
tops out about 30-35 in 8th (8 speed wide ratio sturmey archer hub)
looking at the bike after a ride i realized the hub axel had turned in the dropouts and bent them out 1/2 inch,..,.. too much torque,..
anyway,... i went out to the pile of bikes by the shed and cut off the horizontal dropouts off a bmx (part of the anger management therapy from the bent dropouts was cutting the bmx up like a barbarian with a grinder) and im bolting and then welding the horizontal dropouts on the remains of the normal dropouts,.. the horizontal dropouts are about 2-1/2 times as thick steel as the originals so i hope that solves the problem
11 tooth engine spr.
30 tooth jackshaft input spr.
10 tooth jackshaft output spr
48 tooth crank input
30 tooth crank output
25 tooth rear hub spr.
this gives me about 90 rpm @ the crankset @ 5000 rpm on the motor
the result is a bike that will climb (accelerate up actually) a steep hill
tops out about 30-35 in 8th (8 speed wide ratio sturmey archer hub)
looking at the bike after a ride i realized the hub axel had turned in the dropouts and bent them out 1/2 inch,..,.. too much torque,..
anyway,... i went out to the pile of bikes by the shed and cut off the horizontal dropouts off a bmx (part of the anger management therapy from the bent dropouts was cutting the bmx up like a barbarian with a grinder) and im bolting and then welding the horizontal dropouts on the remains of the normal dropouts,.. the horizontal dropouts are about 2-1/2 times as thick steel as the originals so i hope that solves the problem