Problem with chain.

psprat496 · #1 03-17-2010, 06:00 PM

Ok well heres the problem. The chain on my bike seems to tighten and get loose when the bike moves. Instead of like a regular bike where the chain stays the same tension it gets really tight and then loose. At first I thought it was the sprocket but it doesn't seem to be that off and is actually pretty centered. I don't know why it does this and it's really annoying because whenever I hit a certain speed the chain starts vibrating like crazy and makes a very loud sound and the bike won't budge any higher from that speed. Anyone know if this is a common problem or if anything else could be causing thing?

Also the sprocket isn't 100% centered but it is extremely close. Any ideas?

exavid · #2 03-17-2010, 06:15 PM

It takes very little off center on the sprocket to make the chain go slack and tight. On my 2 stroke bike the tension goes from 1/4" slack to almost 3/4" as the wheel turns. There was very little off center when I put the wheel on the bike. I'll take it off eventually and get that sprocket right on the money but right now it's good enough. I think the thing might have shifted a bit in use which isn't impossible since it's only held by a rubber sandwich clamped to the spokes. If you have as much as 1/16" off center on the sprocket it's going to make a fairly large amount of change in chain tension as the sprocket is turned. That's a good argument for an idler pretty close to the sprocket. On my bike there's no idler so I keep a watch on the chain tension. I like running without an idler because it quiets the bike and makes it easier to pedal.

**Bikeguy Joe** · #3 03-17-2010, 06:17 PM

Extremely close may not be enough.

Sometimes the center hole is drilled off center.

If your chain is too tight, it will aggravate the problem.

psprat496 · #4 03-17-2010, 06:29 PM

Quote:

Originally Posted by exavid

It takes very little off center on the sprocket to make the chain go slack and tight. On my 2 stroke bike the tension goes from 1/4" slack to almost 3/4" as the wheel turns. There was very little off center when I put the wheel on the bike. I'll take it off eventually and get that sprocket right on the money but right now it's good enough. I think the thing might have shifted a bit in use which isn't impossible since it's only held by a rubber sandwich clamped to the spokes. If you have as much as 1/16" off center on the sprocket it's going to make a fairly large amount of change in chain tension as the sprocket is turned. That's a good argument for an idler pretty close to the sprocket. On my bike there's no idler so I keep a watch on the chain tension. I like running without an idler because it quiets the bike and makes it easier to pedal.

Never knew that even 1/16 of an inch would distort the chain. Well I guess I'm going to take the wheel off tonight and try to center it up just right because it is very annoying hitting 26 and just have the chain start to scream and feel the bike jerking back and forth. Thanks for the help.

exavid · #5 03-17-2010, 08:47 PM

It's pretty critical to get the sprocket centered. If it goes tight on part of the wheel rotation it's putting a pretty heavy load on the engine mounts and driving sprocket bearing. Effectively it's yanking on the engine each time the wheel turns over.

psprat496 · #6 03-17-2010, 11:27 PM

Quote:

Originally Posted by exavid

It's pretty critical to get the sprocket centered. If it goes tight on part of the wheel rotation it's putting a pretty heavy load on the engine mounts and driving sprocket bearing. Effectively it's yanking on the engine each time the wheel turns over.

Now how do you get around mounting the sprocket? I mean I just spent 2 hours trying to even it all out and it did but not by a lot. The section of the chain leading into the engine still bounces around a lot. I really don't know what to do. I've seen how spooky tooth sells a wheel with the sprocket already mounted on there so I might just have to go for that. Do you know if anyone sells premounted wheels with sprocket already hooked up? I'd actually pay for someone to do this for me it's that frustrating.

bairdco · #7 03-17-2010, 11:33 PM

the chains will "bounce" around on all these engines. they're pretty jerky. it's just a matter of "how much."

if your sprocket is a little off center, but not too loose as to derail the chain, and not too tight like it's trying to pull the engine off, just go with it.

pretty much every bicycle chain has hi and low spots in them also. usually because of the force pedaling, it'll elongate the hole in the sprocket the crank sets in (on a one piece crank) or will tweak the actual sprockets with three piece cranksets. or if the sprocket isn't "true" side to side.

also, when installing the wheel, you need to find the tightest spot in the chain when tightening it down. if you don't, when the wheel rotates to that spot, it's gonna be way too tight.

Cabinfever1977 · #8 03-17-2010, 11:41 PM

Ive always had that problem too, but i seem to have gotten it right this time, i spent more time centering my sprocket and its good and needs no adjustment.

And what Bairdco said is true, when you tighten the chain, first find the part of the chain when its the tightest and tighten it til its too tight then loosen it a little, that way it will never be too tight.

psprat496 · #9 03-18-2010, 12:11 AM

Quote:

Originally Posted by bairdco

the chains will "bounce" around on all these engines. they're pretty jerky. it's just a matter of "how much."

if your sprocket is a little off center, but not too loose as to derail the chain, and not too tight like it's trying to pull the engine off, just go with it.

pretty much every bicycle chain has hi and low spots in them also. usually because of the force pedaling, it'll elongate the hole in the sprocket the crank sets in (on a one piece crank) or will tweak the actual sprockets with three piece cranksets. or if the sprocket isn't "true" side to side.

also, when installing the wheel, you need to find the tightest spot in the chain when tightening it down. if you don't, when the wheel rotates to that spot, it's gonna be way too tight.

Ok well after trying to line up the sprocket a bit it seems to have gotten a little better. I'll actually test it tomorrow and also try what you said about finding the tightest spot and tightening it when it's too tight and see how that works out. I was also thinking of a way to center up the sprocket 100%. If I could bring the wheel down to Home Depot and get a metal, or brass pipe that is just the right size as the hole in the sprocket that would ensure me that the entire sprocket is even. Going to try that this weekend. Let you know how it turns out.

bairdco · #10 03-18-2010, 03:10 AM

when i used the kit mounting crap, i'd get the sprocket snug, then put it on the bike and spin the wheel, holding a marker next to it to mark the hi and lo spots. then i'd tap on it with a rubber mallet at the hi spots.

it's a pian, but it worked.

now i just use sprocket adapters. it's much less aggravating.