help, chain, sprocket

Rogwillsie · #1 11-12-2008, 08:19 PM

Got a new wheel, installed the sprocket as instructed. The sprocket seemed true when I spun the wheel, both off and on the bike. Also, installed new studs for the motor mounts in the back, tightened the motor mounts. With excitement, I installed the chain and tested it with the bike hung up. The chain comes off at the bottom of the sprocket after a few revolutions of the wheel! What do I do now? It must be an alignment issue, I figure. But how do I align?

old motorbike · #2 11-12-2008, 09:28 PM

Sounds either not aligned or too tight. Try loosening the tension to about 1 inch of play.

misteright1_99 · #3 11-12-2008, 09:32 PM

I use a coathanger mounted to the hub of the wheel (I usually align it off the bike) or the chainstay, bend it out to a point that it just touches the sproocket and spin the wheel an tighten the bolts where the sprocket pushes on the coathanger or loosen the bolts where it doesnt touch.

Rogwillsie · #4 11-12-2008, 09:52 PM

Thanks for your suggestions. I'll look at the alignment. This problem is frustrating because when I first got the engine and installed it, it worked like a charm for several rides before I started having problems and nothing but problems since, including a ruined rear wheel. This time I'll add some detail on my actions. I wanted to install without the tensioner so I put spacers in the back motor mounts to move the engine forward, installed new studs. The chain is not too tight, maybe too loose. Should I reinstall the tensioner? Also, the chain isn't just coming off now, it is climbing on the sprocket and locking. Would come off, I suppose, if I tried to ride it.

Creative Engineering · #5 11-12-2008, 10:20 PM

Rogwillsie,

Your last comment is the clue!

You may have a a sprocket that has not been manufactured properly. My last kit had a poor sprocket.

When the chain rides up on the sprocket teeth...the pitch is wrong!

"Also, the chain isn't just coming off now, it is climbing on the sprocket and locking. Would come off, I suppose, if I tried to ride it."

Jim

Rogwillsie · #6 11-12-2008, 10:34 PM

Jim
How do I check the sprocket to determine if it is bad? Also, why did the bike work fine at the beginning? It's puzzling.
Rog

misteright1_99 · #7 11-12-2008, 10:37 PM

The instructions that came with my kit stated that you might have to file or grind the sharp edges off the drive sprocket, I did and didnt have your problem. I also didnt use the kit chain or tensioner very long, I installed #41 chain and a spring loaded chain tensioner. Good luck.....

Creative Engineering · #8 11-13-2008, 06:12 AM

Rogwillsie,

Can you provide a photo?

Being that it was fine at one point, it's unlikely the sprocket is bad. A stretched chain can cause the same problem, but that's unlikely as well.

Jim

xPosTech · #9 11-13-2008, 09:49 AM

New wheel and new engine position. Sounds like a chain line problem.

Is your sprocket dished? If so, you may have reversed it when you mounted it to the new wheel. Whenever I install a sprocket I usually true the rim, true the sprocket, true the rim, etc. My sprockets are not dished, BTW.

Is this on a single speed cruiser with a coaster brake or a multi-speed with derailler? A multi-speed hub with no derailler? All these rear wheels have a different dish. The dish could affect the chain line.

Did you happen to change the type of rear wheel? Change to a wider rim? If so the chain line might change depending on type of wheel, spacers, etc.

Check the chain line with a string from the outside of the drive sprocket to the outside of the rear of the wheel sprocket. There should be no gap or angle in the string at the front of the wheel sprocket. Or just look down the run of the chain from the back. It should run true over both sprockets.

Yes, pictures would help. Show the chain climbing on the sprocket and the run of the chain from the rear.

We'll all get you fixed up.

Ted

Rogwillsie · #10 11-13-2008, 04:23 PM

Ted,
Thanks for your good advice. There is a question I still have. My sprocket is curved and I have it mounted so the teeth are away from the spokes. Is this the right way, or should the teeth be nearer the spokes? A reason i think I may have the sprocket backwards is that when I first installed it, I incorrectly left the outside fiber washer off, which would put the teeth closer to the spokes. It worked fine until the spokes gave out.
Rog