I'm devastated - sprocket/chain issues

I was moving right along with my project and I just realized that my chain is hitting my rear wheel. This is really bad news because I don't have much extra clearance. Here's my set up:
14mm offset front sprocket, 15mm spacer for rear sprocket, 530 quadra x-ring chain, 6" rear rim with a 180/55-17 tire.

I've done a bunch of reasearch and it looks like even the most narrow 530 chain (non o-ring) will still be too wide. I think I need to move the rear out another 4 or 5 mm but they don't make a spacer that size and that may throw off my alignment with the front sprocket.

Does anyone know where I can get a 520 offset front sprocket? I have emails in to several places and will hopefully hear back.





Post edited by: 79MKII, at: 2007/11/26 20:31

Here's a side view of the rear spacer. It's between the sprocket and hub. What about placing a washer behind the sprocket on each bolt?? Not enough support?

Here's a shot of just the rear spacer - the washers would go on top of the holes shown, under the sprocket. Think that would be solid enough? Maybe I'll have to have a solid spacer machined?



Post edited by: 79MKII, at: 2007/11/26 20:38

How much is the chain rubbing? Can you shave the tire a little? Or perhaps switch to a different tire? I know that not all 180mm wide tires are the same width.

Good luck.

Later, Doug

I never thought of shaving the tire, but that's a possibility. It barely hits right where the tread turns to sidewall. I'm guessing I should have gone with a 5.5" rim and the same tire would probably be OK. BTW, I just found a 520 offset sprocket of ebay, but it's only a 1/2" offset. I also found a 520 chain good for up to 120 HP.

Any other opinions on tire shaving? Anyone tried it? That sure might be the easiest solution.

shaving the edge off the tire is a possiblity, I know some places sipe new tires and we groove the race car tires.
you could have a front and rear spacer made the same thickness and install them and use locktite to secure the bolts and nut.

one thought, did you have the back wheel in straight, maybe it could have been off just a bit causing it to rub

BSKZ650 wrote:

shaving the edge off the tire is a possiblity, I know some places sipe new tires and we groove the race car tires.
you could have a front and rear spacer made the same thickness and install them and use locktite to secure the bolts and nut.

one thought, did you have the back wheel in straight, maybe it could have been off just a bit causing it to rub

I'm looking for a rear spacer now. That would be the easiest fix. Jeff at Z1 carries spacers for the front. Regarding the rear wheel being straight - I did check that to make sure. I had the same thought when I first noticed the chain hitting the tire. Thanks

Is there a rule of thumb for tire to chain clearance? Maybe 1/16" or so? I think the tire would get skinnier and taller as it spins, right??

I have found several people willing to "help out" in making a 520 offset front sproket. Problem is the price - $150 and $250 quoted so far. Too much$$...

I would think you would see more movement in the tire in a corner, side wall flex, but I dont think they move much.
had a brain fart:P what about cutting some shim stock to make the needed shim that you need, it comes in a lot of sizes

Ya know, going back to the tire thing. The M1 Metz I think is a little less wide but don't be afraid to run a 170. Unless your gonna make a track bike outta that thing or dragging the knees all over the place you should be fine. Sheet, I have a 160 on my ZRX right now cause that's all I had. Does ok as long as I'm not tossing it way over into the corners.

Ya know, going back to the tire thing. The M1 Metz I think is a little less wide but don't be afraid to run a 170. Unless your gonna make a track bike outta that thing or dragging the knees all over the place you should be fine. Sheet, I have a 160 on my ZRX right now cause that's all I had. Does ok as long as I'm not tossing it way over into the corners.

EA6BMECH wrote:

...The M1 Metz I think is a little less wide but don't be afraid to run a 170...

Yes, I agree. If I had known about the trouble I was going to have, I would have gone with a smaller rim and tire. When I started I was hoping to fit a 200 series street legal drag tire, but wanted to start with a 180 to be safe. Now the problem is that I have a 6" rim that won't accept a much smaller tire, if at all. Not to mention that I'd have to get a new tire and try to sell the old one. I'd lose money for sure, and I've been doing that way too much lately. I'll double check the allowable tire/rim combinations because a smaller tire may end up being the only reasonable solution at this point.