Slipping chain diagnosis

jds_1981

This weekend I replaced my chain (which turned out to be well past the 1% wear level) & took out my rear mech cogs and cleaned.

Unfortunately now when I pedal the chain appears to slip at the back. This depends in part on whether it is on one of the centre cogs or the top or bottom.

I don't think the rear cogs are particularly worn so any good tips on diagnosing cause (before I go out & buy a new set of rear gears)?

optimisticbiker

How old was the chain... and was the cassette changed at the same time as the last chain change?

You did make the new chain the same number of links as the old... buy counting not measuring... and cleaned the rear mech/jockey wheels...

pangolin

Why does number of links matter? Assuming it's not too short to reach or so long the chain ends up resting on itself in the wrong gears.

jds_1981

I didn't make it the same length as last time :oops:
Had chucked it in the bin before I remembered & couldn't be bothered to fish it out so just made sure it was of a length where on reasonable gear crossing it wouldn't have issues (rear mech folded over).
Issue?

jds_1981

Sheldon just has a page on working out a reasonable chain length

http://sheldonbrown.com/derailer-adjustment.html#chain

beverick

Assuming that the cassette is ok, it just sounds as if the gears need adjusting.

Bob

jds_1981

Hmm, I fiddled with the gear adjuster as cycling. Didn't help. Maybe it is the cassette then. Expensive trip to evans at lunchtime I guess

cambs

Did you tighten the derailleur jockey wheels up fully, there shouldn't be any side-to-side play if you wiggle them* (can also happen if they are worn out too)?

If they don't align properly the chain can snag/slip.

EDIT applies more to the lower wheel , a bit of movement is fine for the upper one.

jds_1981

Think the jockey wheels are fully tightened, will double check.
I've ordered a new cassette, will hopefully arrive tomorrow.

daniel_b

Hi there,

do not want to hijack your thread, but I thikn I have the exact same issue as you.

I have a 105 equipped bike, and it was slipping in certain gears, but I could not tell how or why it was slipping.
I changed the freewheel, and this has made no difference :oops:
Aside from denting my wallet of course.

I try and look down when it 'slips' but can't see what is happening, it certainly does not seem like it is hunting between gears, that I am used to experiencing.

Bizarrely, it only seems to slip in the middle set, and not all the time, but in the top set it appears to be fine.
It only slips for part of a revolution, but it worries me that it might do that as I am accelerating onto a roundabout for example.

I will check the rear derailleur, and from the above it looks like it could be the rear cassette that is at fault?

Cheers

Dan

jds_1981

Daniel B wrote:

Bizarrely, it only seems to slip in the middle set, and not all the time, but in the top set it appears to be fine.
It only slips for part of a revolution, but it worries me that it might do that as I am accelerating onto a roundabout for example.

Mine was slipping more in the middle - I looked at mine at lunchtime & I think that the 'shaped' teeth that help shifting may be worn (these appear most vulnerable to wear as thinner) & so it slips more when it reaches these. Will see when I put the new cassette on.

itboffin

You need a new bike.

You're welcome

bracketed

If your chain's worn by over 1%, then your cassette (or at least your most used cogs) will definitely be knackered, as it will have worn to fit your chain. I've just replaced mine at .75%, and I'm getting an occasional skip when starting off hard. I'll be replacing my cassette as soon as my lockring tool arrives...

Initialised

Worn cassette. I had this, new chain, slipping like a clutch on a Rover. Left the old chain on until it gets really bad. It's getting there, hard to index, slips in certain sprockets under heavy load, but I have new cranks/rings, chain and cassette waiting for the fateful day and a lazy fettling afternoon. Might as well do the BB at the same time.

jds_1981

itboffin wrote:

You need a new bike.

You're welcome

I'm already at 'D' bikes. One is hidden at work & the wife doesn't know about it...

jds_1981

New cassette on. Works like butter. Seems even the front changes a bit better now? Wonder if I need to change the front rings too
Also my getting lots of nasty creaking from the bottom bracket under heavy load. Think it's time for a good overhaul..

itboffin

So in the future check your chain more often, keep it clean and lubed and you might but only might mind you make the cassette last a little longer ... or just continue to change them both everytime :?

PS. My wet commuter chain is at 1% almost but i'm swapping wheelset/cassette combos to buy some more time .................................. :roll:

jds_1981

itboffin wrote:

So in the future check your chain more often, keep it clean and lubed and you might but only might mind you make the cassette last a little longer ... or just continue to change them both everytime :?

Yeah, my bad for not changing chain sooner - the nasty weather put me off to my detriment.