Chain slip

benb

Evidence based cyclist
Location
Epsom
Hi all

I've replaced my chain and cassette, reindexed the gears, yet I get annoying chain slip, particularly when starting off. Yet oddly, I don't seem to get it when powering up a hill.

Pretty sure indexing is OK.
Any ideas?
 

Globalti

Legendary Member
Either the indexing isn't OK or the chainring is so worn that the new chain is slipping round it. This happens when you fit a new, unworn chain to an old, worn chainring because the teeth are so worn that the chain will only be contacting the first tooth in line rather than spreading the load over all the teeth. A worn chain will have stretched and was probably working OK with the worn chainring.

Typically this kind of chain slip happens when you stamp on the pedals when setting off.
 
OP
benb

benb

Evidence based cyclist
Location
Epsom
Either the indexing isn't OK or the chainring is so worn that the new chain is slipping round it. This happens when you fit a new, unworn chain to an old, worn chainring because the teeth are so worn that the chain will only be contacting the first tooth in line rather than spreading the load over all the teeth. A worn chain will have stretched and was probably working OK with the worn chainring.

Typically this kind of chain slip happens when you stamp on the pedals when setting off.
I'll double check, but I'm 99% sure the chain slip is happening at the rear.
Maybe I've cocked up the indexing; I'll redo it.

What's the best method?
I put the shifter into 2nd, then adjust the mech until I can hear it just clicking to try and go into 3rd, then back it off again until the clicking just disappears.
Then check all of the shifts up and down the cassette, fine tuning if necessary.
 
OP
benb

benb

Evidence based cyclist
Location
Epsom
Define slip. Is the chain skipping between gears or is it skating over a sprocket?
Hard to say for sure, but I think it's skipping between gears.
So probably the indexing.

Weird thing is, I've indexed my gears plenty of times without this issue. Maybe the mech is bent or something.
Might say sod it, and take it to the LBS and let them deal with it.
 
Location
Loch side.
Hard to say for sure, but I think it's skipping between gears.
So probably the indexing.

Weird thing is, I've indexed my gears plenty of times without this issue. Maybe the mech is bent or something.
Might say sod it, and take it to the LBS and let them deal with it.
OK, that's skipping then, but it helps to identify exactly the right symptoms otherwise you get everyone on a wild goose chase with advice that worked for their grannies and aunts but won't help you in the least. Kinda like the lady complaining about a funny noise under the bonnet.
 

Globalti

Legendary Member
When was the last time you changed the cable outer where it curves round to the rear derailleur? These need changing at least every six months to maintain good clean shifting and more often in wet weather or on a bike that gets washed a lot. While doing that, be sure to clean the inner cable and pull it through your fingers wetted with a little waxy chain lube. You'll be amazed at the manky rusty condition of the steel reinforcements in the cable outer, which is what causes sluggish and inaccurate shifting.
 
Last edited:
OP
benb

benb

Evidence based cyclist
Location
Epsom
When was the last time you changed the cable outer where it curves round to the rear derailleur? These need changing at least every six months to maintain good clean shifting and more often in wet weather or on a bike that gets washed a lot. While doing that, be sure to clean the inner cable and pull it through your fingers wetted with a little waxy chain lube. You'll be amazed at the manky rusty condition of the steel reinforcements in the cable outer, which is what causes sluggish and inacurate shifting.
Good idea, I'll check that out. Thanks.
 
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