Coaster Brake / Sprocket / Spoke problems - MotoredBikes.com: Motorized Bicycle Forum

svongehr · #1 03-24-2008, 04:37 PM

For those of you that have bikes with a 26" 48 spoke rear wheel with a coaster brake, were you able to mount the sprocket without re-drilling the mounting holes? I'm on my third build and have found that with this bike, I only have three of the original holes in the sprocket that I can fit bolts through without running into a spoke. I've never encountered this problem before and the only posts I found were dealing with the mounting bolts hitting the brake arm. I'm about to drill new holes in the sprocket but was wondering if there is another way around this.

Also, how important do you think it is to have rubber on both sides of the spokes? Will just the inside work OK?

The bike is a Greenline cruiser and the sprocket is a 34 tooth from Dax.

srdavo · #2 03-24-2008, 05:42 PM

the easiest solution would be to change the rear wheel to one with 36 spokes. (9 holes in the sprocket, divides evenly between the 36 spokes.)
with 48 spokes you need 6 or 8 evenly spaced holes in your sprocket, to fit thru your spokes....and remember, you have to put washers & nuts in between those spokes, too.

svongehr · #3 03-25-2008, 11:27 PM

If I could kick myself in the head, I would.

Thanks for that. Picking a number of holes that divided into 48 would have never occurred to me.

I drilled 8 new holes and it works perfectly.

Thanks again,

Scott

Large Filipino · #4 03-29-2008, 03:21 PM

How did you do that? Did you drill the rubber and spacers too?

svongehr · #5 03-31-2008, 04:31 PM

On a piece of paper I used the center hole and the pre-drilled holes to find the center of the sprocket. Then I used a compass to divide the sprocket into eight parts and to lay out the new diameter for the eight holes. I taped the piece of paper to the sprocket to use as a guide and drilled the holes with a bench press. Since the diameter of the holes was larger than the rubber spacers I had, I bought a 6X6 piece of flexible coupling from the plumbing department at Lowes. The coupling is made of ¼ inch rubber. After I cut a circle out of the coupling, I sandwiched it between the sprocket and the drill press table and drilled the holes for it by using the new sprocket as a guide. I could not find any flat circular metal for the other side of the rubber so I just used washers.

I think this same idea should work on wheels that have even more spokes and might give it a try once I get extra cash.

I threw in some pictures for those of you interested. The pic of just the sprocket was my trial run. I didn't want to go drilling through my new 34T without making sure it worked first.