New Casette, Part worn Chain

[mythste]

I know, I know, change both, but bear with me here.

Chain is less than 300 miles old. Seemed silly to change it, changed casette from 11-28 to 11-32. Seems visibly straight, changes are still crisp across the entire range. Mech clears largest cog comfortably.

However, in the top 5-6 gears (smallest cogs) there is a definite "dragging" feeling, where I can feel the chain vibrating through the pedals. My mind is telling me that this is simply the slightly used chain bedding into the new casette.

Can anyone think of anything more worrying that might be at play? Or is it a "ride and have a beer" sort of a job?

 

[mythste]

Should have posted in Maintenance etc - @Moderators sorry!

 

[Yellow Saddle]

I know, I know, change both, but bear with me here.

Chain is less than 300 miles old. Seemed silly to change it, changed casette from 11-28 to 11-32. Seems visibly straight, changes are still crisp across the entire range. Mech clears largest cog comfortably.

However, in the top 5-6 gears (smallest cogs) there is a definite "dragging" feeling, where I can feel the chain vibrating through the pedals. My mind is telling me that this is simply the slightly used chain bedding into the new casette.

Can anyone think of anything more worrying that might be at play? Or is it a "ride and have a beer" sort of a job?

The chain's mileage is irrelevant. How long is the chain? That's all that matters in terms of giving your cassette the maximum life possible. If it is near the end of its life, you are just delaying and amplifying your costs later on. But that's your business.

And just to put a red herring aside, note that gear changes have absolutely nothing to do with chain wear. Nothing. Nada. Ziltch. Diddly Squat.

From your description, we know the chain is not worn enough to cause skating (slipping over the teeth) on a brand new cassette and therefore the problem is elsewhere. Let's look forward, to the chainrings. I suspect one chainring is worn. My guess is that you will eliminate the vibration when you switch to the smaller/larger ring than the problematic one. Reason for this is that with a worn chainring, the incoming tooth hits against the incoming chain roller. However, the fact that there is big tension in the upper run sees that the tooth is forced past the incoming roller nevertheless. That moment when it slips past causes such a vibration.

My guess is that you only notice it with the new cassette because you now use the smaller sprockets more and that changed the chain's entry angle enough to make the difference noticeable. Such mismatches usually go away by itself but the reasons for it disappearing are not benign. It means that components have be worn forcibly into a new shape.

Remote diagnostics on these things are not easy. You need to do some homework. Try and see if the vibration persists in a different front gear.
Then posts some nice, face-on in-focus photos of the offending chainring so that we can see the teeth and crank position simultaneously. It is important to see the crank because chainrings wear differently in different stages of crank rotation. On your power stroke the wear is more accentuated.

 

[mythste]

The chain's mileage is irrelevant. How long is the chain? That's all that matters in terms of giving your cassette the maximum life possible. If it is near the end of its life, you are just delaying and amplifying your costs later on. But that's your business.

And just to put a red herring aside, note that gear changes have absolutely nothing to do with chain wear. Nothing. Nada. Ziltch. Diddly Squat.

From your description, we know the chain is not worn enough to cause skating (slipping over the teeth) on a brand new cassette and therefore the problem is elsewhere. Let's look forward, to the chainrings. I suspect one chainring is worn. My guess is that you will eliminate the vibration when you switch to the smaller/larger ring than the problematic one. Reason for this is that with a worn chainring, the incoming tooth hits against the incoming chain roller. However, the fact that there is big tension in the upper run sees that the tooth is forced past the incoming roller nevertheless. That moment when it slips past causes such a vibration.

My guess is that you only notice it with the new cassette because you now use the smaller sprockets more and that changed the chain's entry angle enough to make the difference noticeable. Such mismatches usually go away by itself but the reasons for it disappearing are not benign. It means that components have be worn forcibly into a new shape.

Remote diagnostics on these things are not easy. You need to do some homework. Try and see if the vibration persists in a different front gear.
Then posts some nice, face-on in-focus photos of the offending chainring so that we can see the teeth and crank position simultaneously. It is important to see the crank because chainrings wear differently in different stages of crank rotation. On your power stroke the wear is more accentuated.

Some good and interesting points here, I'll report back on my ride home.

Initially, however, you might very well have a point with regards the front chain rings being worn, I hadn't considered this and I think that would make sense as to why the feeling is very much in my feet. The idea that a vibration would be able to travel so consistently from the rear cassette would be unlikely I suppose. Memory tells me I only have this feeling in the big chainring as well, but again, I'll confirm this after my ride home tonight and with a bit of luck some photos to follow.

Thanks, as always for the comprehensive reply YS.

 

[uclown2002]

well......................

 

[gbb]

New chain, part worn cassette has given me that mechanical vibration sensation a couple times...I think it's just bedding in, mine went after 50 miles max.

 

[mythste]

Goodness! Forgot to update this! Sorry folks.

So the sensation has lessened after 150 miles - but I think the issue does lie with the big chain ring needing replacing in the near future. I'll take some pictures this evening for verification.

The plan is to keep this running until the chain starts to show signs of wear and then replace cassette, chain and chain rings all in one go next time round.

Nextup, solving headset wobble. Never ending at the moment!

 

[gbb]

Goodness! Forgot to update this! Sorry folks.

So the sensation has lessened after 150 miles - but I think the issue does lie with the big chain ring needing replacing in the near future. I'll take some pictures this evening for verification.

The plan is to keep this running until the chain starts to show signs of wear and then replace cassette, chain and chain rings all in one go next time round.

Nextup, solving headset wobble. Never ending at the moment!

While you have it under control from your point of view, you have a nearly new chain, a new (i assume) cassette and worn chainring....depending on your crankset make, a chainring is relatively cheap compared to buying all three...i'd be buying a new chainring now and save prematurely (and needlessly IMO) ruining a chain and cassette.

Just my opinion

 

[steveindenmark]

I had the same thing yesterday. I dropped into my lbs and got him to change the rear cassette and not the chain. the chain had got about 1000km on it. After a few minutes riding I was going to go back and get a new chain. But during my 100km it sorted itself a lot. I will see how it goes over the next few days.