Rear Sprocket ?

Deeman69

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Resently I tried changing the stock 44 tooth rear sprocket to a 41 (9-hole). The new 41 will not fit correctly on the chain (415 size). I have filed and ground the teeth ever so slightly to get a closer fit, but the chain still wants to jump the sprocket. I got the sprocket from GasBike, and my question(s) to ya'll is/are... Are all these sprockets made by the same outfit? Will ordering another sprocket from a different outlet get me better or the same results. Thanks in advance for sharing your knowledge!
 

Chainlube

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Resently I tried changing the stock 44 tooth rear sprocket to a 41 (9-hole). The new 41 will not fit correctly on the chain (415 size). I have filed and ground the teeth ever so slightly to get a closer fit, but the chain still wants to jump the sprocket. I got the sprocket from GasBike, and my question(s) to ya'll is/are... Are all these sprockets made by the same outfit? Will ordering another sprocket from a different outlet get me better or the same results. Thanks in advance for sharing your knowledge
YMMV, too many different makers making what they think is the same thing. The best way to check the cut on a sprocket is to get a drill bit, (I think1/2", but check all your sprockets) and lay it across the sprocket. If the gut is too narrow the bit won't fit and the sprocket needs adjustment. I had a drive gear like that, it just wouldn't let the chain sit in there correctly.
 

Mike St

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You might have the same problem I did. It was the chain which I solved by
buying the heavy duty, wider number 41 chain. I'm fairly sure the 41
chain will solve the problem. You can buy it from several places including
Tractor Supply.
 

Nickt919

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This is my first go round with a motorized bicycle and I do know I have a lot to learn. After buying an Ebay kit I bought 2 more counter sprockets and another rear sprocket before I hit on something decent enough so that the chain would ride the teeth half way acceptable. After getting mine aligned I just ran it until the chain and teeth wore in enough to quiet down. I saved the worst counter sprocket. It's amazing how distorted the teeth are.
After getting it aligned the chain would still go tight, loose, tight, loose because the chain wouldn't ride down in the teeth the same amount as the gear turned and the rear sprocket was out of round.
I've read threads about filing to shape teeth points and I realize you get what you pay for but having to file down in the sprocket teeth for pitch seems just not worth the effort for me. I was ready to throw the towel in and call this project. This big sprockets are not near concentric and slightly warped.

I would have tried the CDH Power CNC rear sprocket but couldn't find a CNC counter sprocket. I gave up rather quick on my search for these items. I didn't want to match a good rear sprocket...if the CNC sprocket is in fact good... with a trash counter sprocket. As I wrote above, I got it close with a couple of the sprockets and ran it until the chain and teeth wore in. It's far from being correct but it's a lot quieter now after a few hundred miles.

To answer the starter question...I think these sprockets are cut out and stamped out by many different manufacturers with no sort of quality control to match the gears to a 415 chain... all the Chinese 415 chains are probably different too.
My limited experience is the sprockets I bought from all different vendors were all distorted in different ways. I'm running the 44T and really would like to try a 40T but I'm just not ready to go through this rigmarole again.
 

Heavyload

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Nov 25, 2021
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I purchased the CNC adapter w/40 tooth sprocket. Had issue with 3 countersunk sprocket holes aligning with adapter holes when clamped tight to hub B.B. Said its just cosmetic, just file your sprocket hole. I knew that was bull, problem was the adapter to wheel hub fit. Solved by shimming between adapter and hub. Used aluminum can for shim stock and wrapped my hub. Now sprocket runs concentric and all holes are aligned. Hope this helps anyone having these issues.
 

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