Chain slipping

Trigger369

Über Member
Hi all . Some of u might remember I recently replaced a worn chain on my bike. I tested the bike on the turbo and all was good with the gears . Different story today when I went outside for a club run .
Gears changing ok but when I put any power down the chain slips and I need to back off . I didn't replace the old cassette by the way . What do I need to do to adjust the gears ? Any help appreciated thanks.
 

vickster

Legendary Member
Why didn’t you change the cassette? How many miles had the chain done? How worn was it?
I’d personally change the cassette ASAP before it knackers the new chain
 
OP
Trigger369

Trigger369

Über Member
Why didn’t you change the cassette? How many miles had the chain done? How worn was it?
I’d personally change the cassette ASAP before it knackers the new chain
Cant say how many miles the chain done but quite a few in the near 2 years it was on . I really didn't think the cassette was all that worn but I was obviously wrong.
 

vickster

Legendary Member
Cant say how many miles the chain done but quite a few in the near 2 years it was on . I really didn't think the cassette was all that worn but I was obviously wrong.
If you’ve done over 1500 miles say in all weathers, I’d think you’d have been riding a worn chain and so a worn cassette. I always have the two changed together (same cost for fitting) and then you know where you’re at. My 10 speed cassettes cost under £25
 
OP
Trigger369

Trigger369

Über Member
My cassette is 9 speed 11 32 . I can see one on halfords site they have the same sram cassette for £19 50 . Will that work with sora groupeset ?
 
If you change a chain, that hasn’t been treated like some sort of princess, and don’t change the cassette, at the same time, you get the slippage you describe. The chain and cassette wear in unison, and form a ‘mesh’. Putting a new chain on an old cassette will not have the same wear pattern / ‘mesh’ and slippage happens under proper power. ‘You can’t teach an old cog new links’ as the saying goes. Eventually the new chain may settle and re-mesh, but not before you’ve added to the wear on the old cassette, and worn the new chain prematurely. Unless you’re running SRAM red / Campagnolo super record / Dura Ace components, it’s a false economy to not change cassettes and chains in unison, unless you’re very careful to keep them spotlessly clean and lubed. Then you could get up to about 3 chains per cassette ( depending on how much work the chain is subjected to ).
 
It is unlikely that the problem is related to indexing so adjusting the gears will not help.
When fitting a new chain to an old cassette it is always a bit of a gamble whether or not it will run ok. It's not unusual for the chain to be ok except on one or two of the gears you use the most. Whenever i replace chains i usually have a spare cassette on standby just in case, even if it is not needed this time it will be ready for next time. Strangely, they often run ok at first then start skipping after 5 or 10 miles then steadily get worse?

Cassettes are much of a muchness, Sram or Shimano are interchangeable just get anything midrange (PG950 or HG50). I ran Sram PG950 cassettes for many thousands of miles on my last commuter and felt they were a bit longer lasting than Shimano equivalents.
 

vickster

Legendary Member
My cassette is 9 speed 11 32 . I can see one on halfords site they have the same sram cassette for £19 50 . Will that work with sora groupeset ?
Yes, I use Shimano Tiagra cassettes with my SRAM Apex or Rival set up as they are at least a tenner less than sram ones. SRAM chains though as they come with the quick link
 
OP
Trigger369

Trigger369

Über Member
Cheers folks . I have just purchased a cassette and tools to do the job . For £30 all in . Time for a bit of maintenance . Thanks agian
 

Ajax Bay

Guru
Location
East Devon
If you change a chain, that hasn’t been treated like some sort of princess, and don’t change the cassette, at the same time, you get the slippage you describe. The chain and cassette wear in unison, and form a ‘mesh’. Putting a new chain on an old cassette will not have the same wear pattern / ‘mesh’ and slippage happens under proper power.
One has two choices (starting from new/new):
A) Ride happily until you get slippage (the wear on the cassette will not be apparent). Do not measure the chain (except for interest/data gathering). Replace chain and cassette together. I did this in 2017 and changed both at about 3600 miles. My current 'matched' set has done about 2200 miles but they will be changed 'early' (ie before any slipping experience) for the long rides of the late spring - I don't want slipping to start on the way up Snowdon/Pen-y-pas in the middle of a 600 qualifier.
B) Ride happily for 1000 miles and then change the chain (even if, when measured the elongation is less than 0.5%). Do not discard the old chain. The new chain should be fine. If it is not - test before riding any distance from home - refit old chain and continue on forced option A (above). Replace the second chain after about the same distance. Ride the third chain following protocol in option A (above). Last year I did this (9sp) and changed the chains at 1500, 1300 and then both 1300 miles later (the cassette having done 4100 miles by then).
Just going on these data, one can see that running both together is probably more economic unless the cassette's for your bike are expensive. It's certainly less hassle - no measuring required - but keep an eye on distance ridden since the change and consider bringing replacement forward before an important/long ride.
Commenting on rr's analysis.
From new, both chain and cassette wear, but because a new/nearly new chain is not elongated the cassette experiences much less wear in the early days of a chain. And so by replacing the chain before it's elongated much, you will find that putting a new chain on a slightly worn (ie 1000 miles, say) cassette will not not result in "slippage under proper power".
 

Ajax Bay

Guru
Location
East Devon
[QUOTE 5577800, member: 9609"]I got some chains up to 3% wear before slipping by doing this. Used 4 chains and just kept rotating them about every 500 miles - got nearly 15000 mile out of the cassette. [/QUOTE]
You're a legend, @User9609 . Chainrings used with well worn chains will wear, so I'll bet you were using a sensibly priced chainset during this.
 
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