Shimano 10sp cassette uneven spacing and shifting issues

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wafter

I like steel bikes and I cannot lie..
Location
Oxford
Shifting issues prompted me to check the sprocket spacing on a problematic 10sp cassette; which in places looked wonky.

The plain shanks of 0.1mm increment drill bits were used as go / no go gauges around the circumference of the gap that separates each sprocket from the next.

The short of it is that pitch ranged from between 3.8 and 4.3mm, with the average coming in at 3.97mm which correlates well with Bike Gremlin's published value of 3.95mm.

This seems like an enormous variation; and unsurprisingly the shifting issues correspond with sprockets subject to the most erroneous spacings - I can't get a clean shift in both directions across those with the largest spacing; only in one direction at a time as cable tension is manipulated.

This seems like a really weird fault - has anyone else experienced similar? One pair of affected sprockets are fairly large so I can see how one could perhaps be warped / dished; however the other problem area is between the two smallest sprockets and I'm at a loss to see how this could have happened..
 
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88robb

Active Member
Location
Netherland
That's a huge variation and definitely the cause of your shifting issues. I've seen it from a bent spider, a warped sprocket, or a bad spacer. You can't fix that much error; you need a new cassette.
 
OP
OP
wafter

wafter

I like steel bikes and I cannot lie..
Location
Oxford
That's a huge variation and definitely the cause of your shifting issues. I've seen it from a bent spider, a warped sprocket, or a bad spacer. You can't fix that much error; you need a new cassette.

Thanks - really appreciate the validation as it was driving me a bit mental and now after measuring seems so obvious yet unlikely.

Potentially weird that it occurs at opposite ends of the cassette.. I was musing on this last night and I don't think it's due to warped sprockets as the problem seems to exist at their root / next to the spacers. While I could conceivibly replace the smallest sprocket - as this has no separate spacer so the issue must lie with the sprocket itself - the issue at the other end lies between sprockets 2&3 (counting from the largest) which according to the Shimano docs are all riveted together..

I wonder if there were some QC issues during Covid, as this would have been produced around then and tbh the rest of the bike is a bit of a shitheap :sad:
 
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SpokeyDokey

68, & my GP says I will officially be old at 70!
Moderator
Thanks - really appreciate the validation as it was driving me a bit mental and now after measuring seems so obvious yet unlikely.

Potentially weird that it occurs at opposite ends of the cassette.. I was musing on this last night and I don't think it's due to warped sprockets as the problem seems to exist at their root / next to the spacers. While I could conceivibly replace the smallest sprocket - as this has no seprate spacer so the issue must lie with the sprocket itself - the issue at the other end lies between sprockets 2&3 (counting from the largest) which according to the Shimano docs are all riveted together..

I wonder if there were some QC issues during Covid, as this would have been produced around then and tbh the rest of the bike is a bit of a shitheap :sad:

If ever I need something analysed in some detail, I am giving you a shout. 😁
 

roubaixtuesday

self serving virtue signaller
10s cassettes aren't that expensive. Must be worth buying one to see if it solves the problem.

Worst case: you've got a spare ready when the current one wears out.
 

C R

Guru
Location
Worcester
Thanks - really appreciate the validation as it was driving me a bit mental and now after measuring seems so obvious yet unlikely.

Potentially weird that it occurs at opposite ends of the cassette.. I was musing on this last night and I don't think it's due to warped sprockets as the problem seems to exist at their root / next to the spacers. While I could conceivibly replace the smallest sprocket - as this has no separate spacer so the issue must lie with the sprocket itself - the issue at the other end lies between sprockets 2&3 (counting from the largest) which according to the Shimano docs are all riveted together..

I wonder if there were some QC issues during Covid, as this would have been produced around then and tbh the rest of the bike is a bit of a shitheap :sad:

Counterfeit cassette?
 

Gunk

Guru
Location
Oxford
I’ve been working on a 9 speed Specialized Cirrus at work which we couldn‘t get to shift properly after fitting a new chain and cassette, after swapping inner and outer cables then the shifter, I then removed the rear mech degreased it and still no improvement. In desperation I fitted a brand new rear mech and that solved it.
 

All uphill

Still rolling along
Location
Somerset
A quick Google search suggests the bigger cogs on a 10sp Shimano cassette are spaced further apart than the smaller ones.

I believe I read years ago the extremes (low and high) are spaced further apart to compensate for the derailleur movement describing an arc, rather than a straight line.
 
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