making a brake disc a sprocket?

Jan 24, 2012
143
21
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letterkenny, ireland
Hey guys I know anyone who reads this may think I am off my rocker but I am considering a occ chopper build and just so happen to have a scooter front wheel and was entertaining the idea of making it my back wheel by having the brake disc drilled and shaped on the outer edge to make it a Sproctor I think the term is but basically have a disc brake and sprocket in one? Would this work do you think or is it a little ott?
 

Wild Bill

New Member
Jan 29, 2013
478
1
0
Camarillo So. Cal.
They already do it on motorcycles but the sprocket would have to be hard enuff not to wear too fast and thicker than the typical bicycle brake disc to match whatever given chain size you run. So you will have to make your own disc/sprocket unless you run one for a motorcycle, in that case you would have to run the larger brake caliper along with it, which also means running the larger brake master cylinder for it. That would be a heavy set up and Im not sure the sprocket size you want would be available.
 

Tony01

Well-Known Member
Nov 28, 2012
1,397
857
113
sf bay area
It's way too much work and you'll never get the proper tooth profile and will end up tearing up your chain and sprocket. Better to find a sprocket you want and drill it for the bolt pattern. Make sure it's dead nuts on center or you will have a chain with varying slack.

Also you will always get crappy braking with the chain grime getting between the disc shoes. With some engineering if you made your sprocket very large and with a large hole inside, mounted to the wheel with a special adapter you can run the caliper on the inside hole of the sprocket (hollow center). Good idea in theory but difficult in practice. Heat dissipation being the biggest plus. A regular disc on the other side would work great too though, and it's a lot easier to setup.
 
Last edited:
Jan 24, 2012
143
21
18
letterkenny, ireland
They already do it on motorcycles but the sprocket would have to be hard enuff not to wear too fast and thicker than the typical bicycle brake disc to match whatever given chain size you run. So you will have to make your own disc/sprocket unless you run one for a motorcycle, in that case you would have to run the larger brake caliper along with it, which also means running the larger brake master cylinder for it. That would be a heavy set up and Im not sure the sprocket size you want would be available.
Bill the plan would be the brake disk on the wheel and figure out what size sprocket I could make it and maybe sand or machine down outer lip to right thickness and with bench drill and a sprocket of me size as guide drill the brake to same size. I assume it may take a few sessions of drilling so as not to burn out drill but seems easy enough
 

Chaz

Well-Known Member
Jun 3, 2012
1,004
70
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Vancouver, British Columbia
I admire your enthusiasm. My biggest concern would be how to keep that rotor clean of grease from the chain. Equally concerning is how to make those sprocket teeth perfectly even.
 
Jan 24, 2012
143
21
18
letterkenny, ireland
I admire your enthusiasm. My biggest concern would be how to keep that rotor clean of grease from the chain. Equally concerning is how to make those sprocket teeth perfectly even.
Chaz the grease thing I would avoid simply by using chainwax as a lubricant. My plan about getting perfectly even teeth on it I mentioned in the last post by using another sprocket as a guide for drilling and then just try pedalling for a bit to see how the chain behaves.

On to a slight favour from you guys would any of yous know what sprocket would be 210mm in diameter as that is the size of brake disc I have on the wheel that I am considering using.
 

Tony01

Well-Known Member
Nov 28, 2012
1,397
857
113
sf bay area
On to a slight favour from you guys would any of yous know what sprocket would be 210mm in diameter as that is the size of brake disc I have on the wheel that I am considering using.
Easy. 210mm is approx 8"subtract two roller diameters -.625, circumference is then approx 22" and divide by your tooth pitch, so for 1/2" pitch this would be a 44t sprocket (approx)

Put this in your calculator
[210mm/25.4mm - 2*rollerDia]*pi/toothpitch