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Hello all

Looking for some pointers/help.

I recently measured chain and was shocked to see that after 8 months and 3000km the chain has stretched to over 1%. I replaced the chain, and when out riding I started to get terrible chain slip (not slipping up and down the gears) but riding over, i think the cassette. Prior to the chainswap I had no problems, hving been out in strong winds and pedaling hard.

I thought the cassette might also be worn or the pawls so checked with three other wheels and cassettes, still same problem. Thought it might be a duff chain, so changed that, no difference. Thought on the off chance that all cassettes were worn, so bought new one (slowly, buying new groupset part by part here). I had a look at the front small chainring and it looks slightly worn but not bad. The slip only occurs when I am in the small chainring at the front and the 4-5 smallest gears at the back (yeah i know I shouldnt be crosschaining)

Could worn jockey wheels cause the chainslip? (these are even newer about 7 months and are Hope jockey wheels) or is it more likely the front chainring. Options left are new derailleur or chainring.

An thoughts greatly appreciated.

54 comments

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Man of Lard [345 posts] 4 years ago
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Is it the same on all front rings? If not then you need to replace the one that's worn (just had exactly the same - replaced cassette & chain - slipfest on one ring - ring replaced, happy days)

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mrmo [2099 posts] 4 years ago
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i would look to the cassette, very unlikely to be the chainring. The attached was what was left of a Campag Record Chainring when it started to slip.

Jockey wheel is likely to show as worse shifting in my experience.

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Haggisbasher [32 posts] 4 years ago
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Thanks, I have tried 3 different cassettes on three different wheels, still slipping. even bought a new cassette today.

It does not seem to slip on the front chainring, but that could be simply unable to push as hard on them, dunno. The front looks more worn than the smaller chainring. I tend to use the larger chainring more.

Changed jockies over tonight and still slipping. It must be a wear issue as it was all okay and smooth as a babies bottom prior to chain change.

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lisa76uk [52 posts] 4 years ago
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Silly question, but you've bought the right width chain? Could cause the slipping issue. Road chains are generally 3/32", 11 speed is slightly narrower than 8/9/10 speed. single speed/fixed is different altogether at 1/8".

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Haggisbasher [32 posts] 4 years ago
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At this point there are no silly questions. Yes the first chain was a KMC 10 speed chain, with a 10 speed fast link. The second was a different KMC chain, 10 speed (stamped on it)

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SPAM Naval [139 posts] 4 years ago
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Check that you tightened the lockiring fully on the new cassette and there is no play in the cassette on the free hub..
I do find when I change my chains and cassettes that sometimes (and I've never worked out why!) it takes a few rides to settle in, as initially I do experience chain skip..

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Wilts Cyclist [14 posts] 4 years ago
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I had this problem on new bike when I swapped the cassette out for a new 11-28 (from 11-25) and replaced the chain at the same time - I figured I'd need a slightly longer chain. Despite careful measurement the chain was too long, it had too much slack and slipped - particularly when under pressure, changing gears or over rough bits of road. I just shortened the chain of course, worked fine ever since.

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Haggisbasher [32 posts] 4 years ago
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Checked the lock ring on all 4 cassettes, no joy.

I swapped like for like in terms of cassette, and measured the number of links on the old chain and copied that for the first new chain, the second chain I actually fitted the chain, with help the old fashioned way, worked out same amount of links.

I really do appreciate the help, it just reinforces everything, I have tried and I have missed noting obvious.

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RR [46 posts] 4 years ago
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It's also worth checking the gear cable. If there is a kink in it, or if the outer is damaged or not properly seated somewhere, then that can act a bit like a spring and cause similar behavior.

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allanj [207 posts] 4 years ago
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Another vote here for potential cable issue- I had this, the chain slipping was in fact the mech moving around and trying to half change gear. I think this happened during big efforts as the rear end flexed enough to cause some cable movement. Shifting was also a bit of a pain at this point (but mostly OK), new cables made a huge difference .

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Nick0 [185 posts] 4 years ago
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I'd suggest rechecking the chain length first, try putting a bit more tension into the derailleur to close it around the cassette, and failing these replace the chain ring.

Have you notice whether it's front or rear slipping?

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bigmel [116 posts] 4 years ago
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If the chain is slipping up and over the cassette teeth or the chainring teeth (i.e. not changing gear side-to-side) then the chain is not sitting in the teeth properly.

Interesting that you say it occurs on the smallest cogs. These require the chain sideplates to sit in the gap between the cogs so that the rollers engage the teeth. A chain that was too wide won't fit into the gap but you have checked that?

A skipping new chain normally indicates that the cassette teeth are worn.
If you also have a new cassette then look at the distance between the top jockey wheel on the derailleur and the cassette to make sure the chain is being fed onto the teeth properly with only a minimal gap between the jockey wheel and the cassette (look up the "B-screw" on t'interweb) and that the top jockey is not behind the wheel axle (feeding onto the back of the cassette so it only catches 2 or 3 teeth).
Sometime the rear derailleur doesn't pivot (rotate) fore/aft and becomes stuck - this will also lead to poor chain feeding.

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Simon E [3593 posts] 4 years ago
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Jockey wheels should last years and work fine, even when worn.

A chainring would have to be very badly worn for a chain to jump or skip. It won't be the same as a cassette-chain mismatch (and the latter is far more likely).

Are you sure it's only on the inner chainring?

If you're sure you have replaced both chain and cassette then I'd look at the gear cable or the rear derailleur.

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DaSy [872 posts] 4 years ago
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Did you remember to put the 10 speed spacer behind the cassette when fitting the new one?

They don't appear to Mavic or 11 speed hubs from what I can see in the picture, but if they did happen to be, you would also need the Mavic specific or 11 speed specific spacer too.

The chainring looks to be okay condition, but have you taken them off recently? Those Shimano F type rings have an offset, so have to fitted the correct way round.

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Haggisbasher [32 posts] 4 years ago
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Hello all. I really appreciate the time that everyone has taken to respond to my request for help

Tonight I am planning on setting up the bike on the turbo and trying to film the problem. I think I can rule out cassettes as I have tried 4 now ( 3 old and one new)

Nor is it the chain, it's non directional and all the speed links are new.

It does not seem to slip in the big ring.

So I have ordered a new dérailleur (being a muppet forgot the obvious and get a new hanger) and new chai rings, if for no other reason, to make most parts new. trust me this is hurting me as I don't have cash to burn, but this is the first nice bike I have owned.

So cabling, derailluier or chainring is left.

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Simon E [3593 posts] 4 years ago
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I wouldn't rely on old cassettes when troubleshooting - use a new chain and new cassette only, swap it between wheels.

Why not get the mech hanger alignment checked at LBS? They did that with mine when I had rear shifting woes recently, it's a 2 minute job.

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Haggisbasher [32 posts] 4 years ago
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I have used 4 different cassettes, three with less than 500 miles on them and one, brand new out the box. All on different wheels.

Defnately only slips when out on the small chainring went out tonight and stamped on the pedal in big chainring rock solid.

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Haggisbasher [32 posts] 4 years ago
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Here is the rear view of the rear derailleur. bike is ont a side stand so slightly tilted.

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Matt eaton [741 posts] 4 years ago
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Something looks a little wonky to me, maybe the derailleur has taken a knock and the gear hanger is slightly bent?

Then again, it could just be a trick of the light or I might have my eyes in wonky.

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shearer27 [25 posts] 4 years ago
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Looks to me like your chain is too long? Derailleur looks too horizontal - it should be in this position when you are in the highest gear (small cog). It shouldn't slip if you have a new chain and cassette. I blame chain length or rear derailleur set-up.

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simon.thornton [44 posts] 4 years ago
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Have you thought of getting an allotment / taking up vegetable gardening instead ?
Lots of fresh air / good company and no slipping chains.

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jacknorell [1027 posts] 4 years ago
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Can't say for sure without photo from the side, but the derailleur looks to be in a very strange position and fully relaxed.

Did you not shorten the chain correctly? Smaller chainring?

No tension means the chain *will* slip on bumps... even small ones.

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Chris James [449 posts] 4 years ago
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I think the derailleur hanger looks bent inwards too. That would explain different shifting on the two chain rings as well.

It is very difficult to eyeball, and the photo might be misleading. Do both the jockey wheels align exactly below the sprockets on the cassette? It is a five minute job at the bike shop to check it. 10 speed is very sensitive to hanger alignment.

I have two kids and race cyclocross, so I am well used to the woes of bent derailleur hangers!

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bigmel [116 posts] 4 years ago
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I assume the chain was on the small chainring at the front?
Hard to be sure without a side-on shot as well, but it looks like the chain is too long. You mention the problem is only on small/small combinations - this is when the derailleur has to flex right back to take maximum slack out of the chain.
You still have 4 smaller cogs to shift to but the derailleur is already pretty much horizontal without much capacity left. As mentioned, it should look like this when on small/small.
The derailleur also seems a too far rearwards. You are only on the middle cog yet it seems to be feeding onto the rear of the cassette.

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DaveE128 [1009 posts] 4 years ago
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When I replaced the chain and cassette on a mountain bike a while back, the wear on the middle ring was enough to cause slipping when I put the power down. The chain slipped on the chainring but it was hard to tell where the slip was happening. Replacing the chainring eliminated it. Hope it will for you too.

However, as others have said, the angle of the rear mech looks weird - the body of the mech seems to be rotated back and up from its normal position. Can you take a photo from the side of the bike in the same gear?

The chain routing through the rear mech also looks funny but it may just be the perspective and the odd angle of the cage. Again, photo from the side and we'll be able to tell if all is well.

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RR [46 posts] 4 years ago
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It's hard to tell much from a single picture. Though I also think the derailleur pulleys don't look adjusted inline with the cogs - possibly a bit too far to the right. Also something maybe be funny about the barrel adjuster; I can't see the lip of the inner metal bit, is it just fully wound in? And the ferule on the end of the cable doesn't look like it is sitting straight in the adjuster. However it's probably all just the light!

Was the new chain shortened to the same length as the old one? If it was and there were no problems before, I'd then assume the problem is something else. If the chain doesn't sag or rub back against itself with the small chainring and small cog it's probably not the issue, though it may be worth sizing the length properly.

I would consider finding a bike shop with a good workshop if you are stumped. Paying someone with the experience and who can see the bike first hand may work out cheaper than throwing new parts at it when the old parts might actually be fine.

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DaSy [872 posts] 4 years ago
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Can you provide a photo that is taken side on to show the whole drive-train?

From that picture it is really hard to tell, but the hanger does look off, as the top jockey wheel looks to be at an angle to the chain as it runs onto the cassette. Also it may be the angle of the photo, but the main mech body appears to be pulled right back, and with that amount of slack in the chain a conventional mech wouldn't sit like that. Is it stuck in the rearward position?
My guess is you pulled it back to get the wheel out, and it has got stuck in that position.

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Haggisbasher [32 posts] 4 years ago
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Thanks all for the comments, the chain has the same links as the previous one and the one before that. Going from the comments, it would appear the derailleur is the most likely problem, or the hanger.

I will seek professional help from brother in law at weekend or LBS after that. Just need to find one that has a good mechanic.

I will take a side picture, and when I find the problem, I will be sure to let you all know.

Thanks everyone for being helpful.

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Colin Peyresourde [1839 posts] 4 years ago
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Could it be the chain length? Silly question in a way. But I bought a chain from Cycle Surgery and was told that it was the right length and I just needed to attach it with a power link. I thought that was unusual. Rode the bike home and the chain slipped all the way - initially thought it was a worn cassette, but after a bit more inspection I realised that the chain was entirely too long.

I was furious at the CS, but also myself at taking the utter rot that they told me as red. I did have an accident, and consider myself fortunate that it didn't happen on a road with cars.

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Haggisbasher [32 posts] 4 years ago
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side pic as requested, Big chainring at front, small ring at back.

The scrape on the derailleur is from a fall many years ago.

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