Rear wheel won't stay in place & my chain chipped the teeth off sprocket

[Michael]

I need help!



My rear tire will slide towards the engine a tiny bit on the left side while riding ... OR ... something somewhere is bending. It's gotten so bad that my chain ate my sprocket (see video below).

Now, this is the scenario:
- Wheel is on tight, adjuster bolts tight, correct amount of sag/play on chain, tire seems straight.

Then
- After a while the chain is noticeably loose, but the nuts and bolts are all still nice and tight.

- I'll loosen the nut, tighten the adjuster bolt with maybe a 1/8 - 1/4 turn, tighten the nut, and be on my way for another ride.  

- A few rides later ... chain is loose again.

Question:
- Why would my tire move like that?
That's the main question. Or is it even the tire moving -- maybe something else is bending.  

Some details:
- I've had to re-adjust the tension several times (maybe a dozen at the most) over the last 6 months.
- I've just noticed that almost all of the teeth on my sprocket have been chipped off.
- Nothing is missing along the axle.
- The chain itself doesn't look damaged at all, not even scratched.
- I lube my chain regularly with Chain Wax
- I try to get my wheel as straight as possible. I use a metal ruler pressed against the sprocket to see how it lines up with the chain whenever I adjust it or reset it after removing the tire.

Any ideas?

Oh, and I made you a video.

Ducati sprocket chain

Some of my theories:
- I'm too heavy for my bike
- I engine break too much
- The sprocket is warped (seems okay after I removed it)
- The swing arm is bending
- The adjuster bolt is stretching (or spinning)
- Something is missing along the axle (it doesn't seem so)
- The bearings are bad (they seemed okay after visual inspection)

[ducpainter]

How many miles on the chain? Worn out chains require frequent adjustment.

Are you adjusting the chain correctly? A bike with stock ride height needs 25mm of chain slack at the tightest point (spin the wheel to find the tight spot).

That sprocket is worn out anyway. Time for a new one, and while you're at it replace the front sprocket and the chain.

Your issues will disappear.

[stopintime]

, but what about the sprocket being worn on one side, mostly - swing arm bearings?

[ducpainter]

, but what about the sprocket being worn on one side, mostly - swing arm bearings?

I doubt it.

I'm thinking alignment.

The parts are sacked so it's really hard to tell. If it was a brand new sprocket and was worn on one side I'd go looking for a cause, but this is just old age IMO.

[mitt]

I agree with dp.  With every part worn out, it is hard to tell the chicken from the egg.  I am guess the multiple tension adjustments were due to an old chain on its way out, and sprocket that was wearing quickly as well.

If the adjusters are tight, and the axle is tight, then the wheel cannot move.


mitt

[Michael]

How many miles on the chain? Worn out chains require frequent adjustment.

Are you adjusting the chain correctly? A bike with stock ride height needs 25mm of chain slack at the tightest point (spin the wheel to find the tight spot).

That sprocket is worn out anyway. Time for a new one, and while you're at it replace the front sprocket and the chain.

Your issues will disappear.

You're probably right on the money, as usually.

My ride height is higher than stock -- just a little bit, less than an inch. So, what then -- how much slack should the chain have in the center if I've lifted the ride height? I never thought to spin the wheel to find the tight spot. I didn't realize it changed.

Both the chain and sprocket have a lot of miles on them. I wouldn't be surprised if it was over 10,000. I haven't replaced them yet and I've had the bike for 2 years now.

I will follow your advice. Hopefully I'll have the new parts on it by this weekend.

In the mean time I'll check all the bearings. It probably wouldn't hurt to just replace them regardless.

[671M900]

Are you definite that the wheel itself is moving? IE, have you looked at the adjusters and the marks and verified that it's moving? If they aren't moving, I'd bet the chain, being worn out keeps grinding into the roller pins. even fractions of a millimeter add up over 98 something links. That combined with all the other parts wearing down contributed.

Did you check the front sprocket as well?

[ducpainter]

You're probably right on the money, as usually.

My ride height is higher than stock -- just a little bit, less than an inch. So, what then -- how much slack should the chain have in the center if I've lifted the ride height? I never thought to spin the wheel to find the tight spot. I didn't realize it changed.

Both the chain and sprocket have a lot of miles on them. I wouldn't be surprised if it was over 10,000. I haven't replaced them yet and I've had the bike for 2 years now.

I will follow your advice. Hopefully I'll have the new parts on it by this weekend.

In the mean time I'll check all the bearings. It probably wouldn't hurt to just replace them regardless.

You should increase your slack to at least 30mm.

There is a process to figure out the required slack exactly, but it really isn't necessary. My ride height is maxed out and I use 30mm.

[erkishhorde]

You're probably right on the money, as usually.

My ride height is higher than stock -- just a little bit, less than an inch. So, what then -- how much slack should the chain have in the center if I've lifted the ride height? I never thought to spin the wheel to find the tight spot. I didn't realize it changed.

Both the chain and sprocket have a lot of miles on them. I wouldn't be surprised if it was over 10,000. I haven't replaced them yet and I've had the bike for 2 years now.

I will follow your advice. Hopefully I'll have the new parts on it by this weekend.

In the mean time I'll check all the bearings. It probably wouldn't hurt to just replace them regardless.

Also, when you adjust your tension, you're snugging the adjuster bolt again after the axle is tightened, right?

[nomadwarmachine]

Very hard for the axle to move if the adjusters are tight. Replace the chain/sprockets, snug up the axle bolt, tighten adjusters, then torque everything to spec, and Bob's your uncle.

[Dietrich]

Michael - Let me know if you need a hand installing the new chain, setting chain tension, etc.  I have the chain rivet/breaker tools, etc.  My observation would be that your chain/sprocket are simply worn out, and also note that you have an aftermarket rear sprocket on there which some heavy handed riders seem to wear out fast.  I run aluminum and have not had problems, but have seen many examples of prematurely worn/broken aluminum sprockets.

[Michael]

Are you definite that the wheel itself is moving? IE, have you looked at the adjusters and the marks and verified that it's moving? If they aren't moving, I'd bet the chain, being worn out keeps grinding into the roller pins. even fractions of a millimeter add up over 98 something links. That combined with all the other parts wearing down contributed.

Did you check the front sprocket as well?

I'm not sure that the wheel is moving, it just seems that way. The chain has gotten loose on so many occasions that I would be really surprised if the chain was simply stretching. The thing that has the adjuster marks isn't what I'd call reliably accurate, so it's hard to tell by that. You'd have to see it to know what I mean.

The hard thing, as was mentioned before, is that there are so many things going on at once it's hard to pin point a single issue other than old age.

Anyway, I did check the front sprocket, and no noticeable wear on that.

[Michael]

Also, when you adjust your tension, you're snugging the adjuster bolt again after the axle is tightened, right?

I am. 

Michael - Let me know if you need a hand installing the new chain, setting chain tension, etc.  I have the chain rivet/breaker tools, etc.  My observation would be that your chain/sprocket are simply worn out, and also note that you have an aftermarket rear sprocket on there which some heavy handed riders seem to wear out fast.  I run aluminum and have not had problems, but have seen many examples of prematurely worn/broken aluminum sprockets.

D, that would be so awesome. I really want to go on the Tortilla Flat ride on Saturday. Do you have time between now and then?

I'm getting my parts through AZSBK, and I'm hoping they'll be in tomorrow. I'll let you know.

[Speeddog]

As others have said, replace the chain and sprockets, your existing parts are sacked.

[ducpainter]

I'm not sure that the wheel is moving, it just seems that way. The chain has gotten loose on so many occasions that I would be really surprised if the chain was simply stretching. The thing that has the adjuster marks isn't what I'd call reliably accurate, so it's hard to tell by that. You'd have to see it to know what I mean.

The hard thing, as was mentioned before, is that there are so many things going on at once it's hard to pin point a single issue other than old age.

Anyway, I did check the front sprocket, and no noticeable wear on that.

Front sprockets are cheap and your chain will last longer if you replace everything as a set.