Geared it to the moon

old motorbike

New Member
Sep 21, 2008
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I use the SBP shift kit and my bike had 5 gears on the rear. Even with that it was still geared a little low. I went with the 11 tooth counter sprocket and was better.
Today I got the idea to use the 3 front chain rings from the bike I took off to do the shifter kit.
2 of the chain rings are bigger than the one on the shifter kit.
I drilled them and installed on front.
The biggest made 1st gear like 5th gear. I could cruise at 30mph in 1st. 1st-3d gears worked but 4-5th were too high and it wouldn't accelerate in them. 30 mph at idle.
Went to middle size gear and perfect. 25-30 mph a little above maybe 2k rpm, just loafing along.
 

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old motorbike

New Member
Sep 21, 2008
352
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74
Fl.
I used the medium one. It seems best ratio. didn't count teeth yet. It's bigger than the one with the kit.
Here it's all flat land, so the lower I keep it the more the motor likes it.
I like to play with gear ratios and I had the chain rings so it was a freebie. Just right for my S. Security budget.
I have it on the big one in pic, but you can see the other in the middle.
 

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xPosTech

The Old Master Motorized Bicycle Builder
Oct 23, 2008
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SETexas
Howdy OM

I just jumped some hurdles and ordered Paul's kit, so maybe he can afford a couple more cheeseburgers. ;) Tell me, do you have to slide the jackshaft sprocket over any when you change from one ring to the other? To go from the big to the middle or back?

I guess I need to break in the chengine before I install the kit? Get it tuned and starting easy?

Ted
 

Ghost0

New Member
Mar 7, 2008
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Bellingham, WA
You do not need to move the jackshaft sprocket because the one that is being changed is the one that drives the rear gears. He may actually be able to swap the two inner chainrings and put on the front derailleur and be able to shift front chainrings on the fly.