Keychain woes?

[dude...]

mines running smoother now its bedded in or whatever

[not_much_for_names]

I have a similar situation with a Keychain, MDS and Thunderbolts and all items are within one or two rides of being new.

After a trial and error process of swapping parts around onto my older drive train I found the Thunderbolts are responsible for the tight and loose spots. The old drive train was a standard chain, beaten MDS and Twombolts and the chain tension was always equal with no questionable spots and the MDS straight.

Turns out the Thunderbolts sprocket bolt hole is a fraction below being level with the sprocket recess and after tensioning the sprocket bolt down then spinning the cranks the disk was pulled out of alignment TOWARDS the sprocket bolt. Backing off the sprocket bolts tension the disk was again nice and straight.

Did all the same again with the Twombolts and they do not cause the disk to be pulled over and never had an issue.

Changed gearing on my spare bike which has Thunderbolts and guess what? Exactly the same issue of chain tension being tight and loose with the disk pulled over to the sprocket bolt.

After looking at the wear pattern on your sprocket it appears you might have a similar situation?

[dude...]

hmmm interesting-maybe get g to look into the tooling for the thunderbolts. i guess you could whack a really thin washer between the sprocket boss hole and sprocket to alleviate it?

[G]

I have a similar situation with a Keychain, MDS and Thunderbolts and all items are within one or two rides of being new.

After a trial and error process of swapping parts around onto my older drive train I found the Thunderbolts are responsible for the tight and loose spots. The old drive train was a standard chain, beaten MDS and Twombolts and the chain tension was always equal with no questionable spots and the MDS straight.

Turns out the Thunderbolts sprocket bolt hole is a fraction below being level with the sprocket recess and after tensioning the sprocket bolt down then spinning the cranks the disk was pulled out of alignment TOWARDS the sprocket bolt. Backing off the sprocket bolts tension the disk was again nice and straight.

Did all the same again with the Twombolts and they do not cause the disk to be pulled over and never had an issue.

Changed gearing on my spare bike which has Thunderbolts and guess what? Exactly the same issue of chain tension being tight and loose with the disk pulled over to the sprocket bolt.

After looking at the wear pattern on your sprocket it appears you might have a similar situation?

Sorry to hear of that. I would check the main sprocket seat on the crank very carefully to make sure there isn't a blob of paint or something preventing it sitting flat. If it isnt easily remedied then we can warranty it for you.


G.

[weedbix]

If it isn't paint then a headless bolt (or overly long one) will sort it

[master]

I have a similar situation with a Keychain, MDS and Thunderbolts and all items are within one or two rides of being new.

After a trial and error process of swapping parts around onto my older drive train I found the Thunderbolts are responsible for the tight and loose spots. The old drive train was a standard chain, beaten MDS and Twombolts and the chain tension was always equal with no questionable spots and the MDS straight.

Turns out the Thunderbolts sprocket bolt hole is a fraction below being level with the sprocket recess and after tensioning the sprocket bolt down then spinning the cranks the disk was pulled out of alignment TOWARDS the sprocket bolt. Backing off the sprocket bolts tension the disk was again nice and straight.

Did all the same again with the Twombolts and they do not cause the disk to be pulled over and never had an issue.

Changed gearing on my spare bike which has Thunderbolts and guess what? Exactly the same issue of chain tension being tight and loose with the disk pulled over to the sprocket bolt.

After looking at the wear pattern on your sprocket it appears you might have a similar situation?

I've ran into the same issue on other cranks in the past, a thin washer or shim solved the problem.

[MSBNL]

^^ I have the same problem with my Wombolts. Not fully tightening the sprocketbolt solves it for me. My Thunderbolts on the other hand are fine.

[14thStbikes]

OG Wombolts came with a thin washer for this very reason. I am running my keychain on said Wombolts with a new sprocket/rear wheel no issues. If I forget the washer, I have a similar issue.

[not_much_for_names]

I have a similar situation with a Keychain, MDS and Thunderbolts and all items are within one or two rides of being new.

After a trial and error process of swapping parts around onto my older drive train I found the Thunderbolts are responsible for the tight and loose spots. The old drive train was a standard chain, beaten MDS and Twombolts and the chain tension was always equal with no questionable spots and the MDS straight.

Turns out the Thunderbolts sprocket bolt hole is a fraction below being level with the sprocket recess and after tensioning the sprocket bolt down then spinning the cranks the disk was pulled out of alignment TOWARDS the sprocket bolt. Backing off the sprocket bolts tension the disk was again nice and straight.

Did all the same again with the Twombolts and they do not cause the disk to be pulled over and never had an issue.

Changed gearing on my spare bike which has Thunderbolts and guess what? Exactly the same issue of chain tension being tight and loose with the disk pulled over to the sprocket bolt.

After looking at the wear pattern on your sprocket it appears you might have a similar situation?

Sorry to hear of that. I would check the main sprocket seat on the crank very carefully to make sure there isn't a blob of paint or something preventing it sitting flat. If it isnt easily remedied then we can warranty it for you.


G.

Hi G, before I sound like I'm trolling or bashing Odyssey/G-Sport/Sunday I want to thank you for making and designing the best parts in BMX.

I know it's not the sprocket seat as I checked every mating part over before assembling. The cranks were then fitted through the bottom bracket and the spindle bolt tightened right down and during this the sprocket bolt was loosely fitted and could be turned by finger tip. The cranks were then spun and the disk was showing as straight (brand new Chase Hawk C-512). Once the sprocket bolt was tensioned down it was immediately noticeable how the disk had been pulled towards the crank arm. Once the sprocket bolt was backed off the disk returned to being straight.

I'm researching into brass shims as this stage to see what thickness would remedy the mentioned issue. 

[MSBNL]

OG Wombolts came with a thin washer for this very reason. I am running my keychain on said Wombolts with a new sprocket/rear wheel no issues. If I forget the washer, I have a similar issue.

I've heard this before but mine didn't include said thin washer (first batch, pre-ordered at empire at the time, still going strong). I've coke can shimmed it before but running a loose sprocket bolt is less of a hassle.

[14thStbikes]

OG Wombolts came with a thin washer for this very reason. I am running my keychain on said Wombolts with a new sprocket/rear wheel no issues. If I forget the washer, I have a similar issue.

I've heard this before but mine didn't include said thin washer (first batch, pre-ordered at empire at the time, still going strong). I've coke can shimmed it before but running a loose sprocket bolt is less of a hassle.

I think the spacey came included after that first batch. I think they may have sent them out to folks who requested one, or reported the issue v

[weedbix]

The sprocket bolt boss doesn't have to touch the sprocket you know gents

[JFax]

Switching to splined drive sprockets was the best thing Ive done on my BMX for years, one less headache.

[montymitch]

UPDATE:
Problem solved. I swapped my 28t Fang for a 25t C512 and all is well. I prefer the taller gearing, but this runs much smoother and I was able to eliminate a half-link and move my wheel back a smidge which fixed the brake clearance problem I had.

I posted this at the beginning of the thread to save you all some scrolling.

[Locomotivebrand]

My Keychain does the exact same thing. It kind of wanders on top of the sprocket teeth where it "enters the sprocket", never had a drivetrain feel this bad . I really like the master link but so far it has not been good to me.