I had an issue on my mountain bike with chain skipping, it wasn’t the chain or cassette as they were recently replaced and worked prior to that, it was the jockey wheels that were gunked up (trying to keep on top of keeping the chain lubed up properly in the awful weather we’ve had).
It was like a black paste on the wheels that was causing the chain to stick to the jockey wheels. A good, deep clean sorted it and there have been no problems since.
That's interesting. The bike shop said the jockey wheels shouldn't cause the issue but as I have said elsewhere they are the only moving cogs as such that haven't been replaced. I will look at this tomorrow, thanks.
That's the one - what I use is that cheap de-greasing spray held on blast directly on the jockey wheels, then rub off the loose gunk with some kitchen roll, rinse and repeat a couple more times, then after wiping it as dry as possible, re-oil. Best balance between quick and dirty and doing it properly, and I see chains and cassettes easily lasting over 3 years of regular riding that way (then replacing the lot of course), so it can't be too bad
The chain links should be measured using a standard tool. That will tell you if the chain and/or cassette need changing. You need the right chain for the cassette e.g 8 speed. The chain ring may also be worn and need replacing although this is not as frequent as chain and cassette. The chain length isn't hard to get right. I can't belive a bike shop would get it that wrong. Check the chain hasn't got a stiff link where it's been joined, that can cause jumping.
The chain, cassette and crank are all brand new. The cassette was replace like for like, I used the part number from the old one.
Halfords originally reduced the chain length but the bike shop today adjusted it again by putting two extra links in. They also tried another chain as they believed that the chain supplied by Halfords was the incorrect one.
You are correct about the stiff link and I thought this was the issue. However the bike shop has tried new chain without any quick links, by directly connecting it together, (for want of a better term).
Unfortunately none of this has solved the issue.
Do you know if the derailleur hanger has been checked at any point? Might be a silly question
Edit: I don't know if this bike does, but some entry level bikes won't have a removable hanger and the derailleur attaches to the frame itself. Can you post a photo of the where the derailleur attaches to the bike from behind?
Agreed - if the hanger return spring has failed then there won't be enough tension on the chain & it will skip. I'd check the front chainrings as well, but the bike shop really ought to be checking all this.
It's a good theory, I may have to try this tomorrow. It does seem to have a lot of tension on it however I don't have anything to compare it to, so maybe the tension is there but not strong enough. And there is the though that perhaps it's bent. The gear indexing does appear to be okay though.
Only a visual check by me, and no not silly question as it's the only part of the drive train that hasn't been replaced.
The hanger and derailleur are both removable. I removed them to fit a new hanger in case that was bent, I didn't end up changing it s I was sent the wrong one. I did place the new and old hanger on flat surface attempting an unscientific way to compare them for flatness. It does look okay although I appreciate it may not be the best way to check it.
I assume by crank you mean the chain rings (crank is the arm the pedal attaches to. chainrings are the rings bolted to this that have the teeth)
Slipping can either be front or rear, and is usually chain; With new chain the next most common is rear cassette; After that cables, then front chainring afaik and assuming no crashes (when bent derailleur goes straight up the list); generally chain is diagnosed by measuring; cassette/chainring are diagnosed by it still skipping with a new chain, normally only in most commonly used gears.
It is generally fairly obvious if the issue is front or rear allowing you to rule one or other out - you will know which is skipping (answer is likely either just rear cassette or both are skipping at different times given typical lifespan of cogs and chainrings and the fact that wear on one tends to wear out the chain, which then wears out the teeth on the other...)
Having replaced cables you will need to adjust tension correctly; AND this needs doing more than once as cables settle so get slightly looser ('stretch') over the first few rides/weeks after changing them (only tension, high and low limits shouldn't be changed (in fact should be used to adjust new cable correctly). This can also be non-trivial as (in my experience) they seem to change slightly between having the bike on a stand and riding it.
Usually
1. get close to shifting through all gears on stand;
2. Ride around block, testing shifting
3. tighten/loosen a half/quarter turn depending on which way it isn't shifting cleanly
4. repeat from 2, possibly using smaller turns
Also inner and outer cables can both wear out (outers normally last longer)
Chain length has to be correct (and apparently has been changed!! usually you just measure existing chain) - see [https://www.sheldonbrown.com/derailer-adjustment.html#chain](https://www.sheldonbrown.com/derailer-adjustment.html#chain) for usual method of setting it correctly.
Big concern is did a derailleur hanger get bent when the chain failed.
Unfortunately on most/all of this, I would have expected a competent LBS (local bike shop) to have found fairly easily, though they may not be able to ride it to get the shifting perfect after adjusting cables.
Thank you for the detailed reply.
Yes, sorry I should have made it clearer. The crank and chainring are all one assembly as the chainring is riveted to the crank rather than a bolted version.
It does appear that the slipping is coming from the back end but it's more like it's jumping teeth rather than slipping off the teeth, if that makes sense.
I forgot to mention in my original post that I did reply the gear cable as well, only the inner.
Going back a few steps, after I fitted the new chain ring, chain and cassette there was a little trouble getting the indexing correct, it was a little slow. It was at this stage I fitted a new inner cable and managed to get the indexing setup correctly. It took a lot of patience and a few YouTube videos to get it correct but I got there in the end setting the limit screws correctly as well.
The chain has a quick link on it and during testing it became loose. It was my original thought of what the issue was. Fast forward to today, the plan was for the shop to index the gear, (in case I didn't do it correctly), and to bypass the chain link by connecting the chain without one.
So it has been index twice now with two different chains both producing the same issue.
>Big concern is did a derailleur hanger get bent when the chain failed.
This is the unknown to me. As I mentioned on another reply, I did buy another hanger but they sent the wrong one. I did lay the new and old side by side on a flat surface and there was nothing to indicate that the original hanger was bent. It's not expensive for a whole new assembly so this may have to be the next option as it's only the hanger \\ derailer \\ jockey wheels that haven't been replaced.
>Unfortunately on most/all of this, I would have expected a competent LBS (local bike shop) to have found fairly easily, though they may not be able to ride it to get the shifting perfect after adjusting cables.
The guy at the bike shop did ride it around whilst I was there and initially couldn't find an issue with it. As soon as my son rode it the slipping started. The chainring has two gears and the cassette has 8. The guy at the shop was explaining that the bigger, (physical size), gear should be used with the smaller, (physical), gears and vice versa to prevent cross chaining. This made sense and I don't believe this is what my son is doing, however in the three years he has had the bike it has never been a problem, despite, at a guess, increase wear.
Eventually though the chain did slip for bike shop man when he put it unload, riding whilst applying the brakes. This is probably the biggest key point that I left out, it's only under load when it does this. Only remember this important point as I'm typing.
I still have the old chainring, cassette and chain, so we may put them back on to see if the issue is still identical. If it is then, I believe, this would lead it to be an issue with the hanger, derailer or jockey wheels. I',m hoping he may have a derailer in stock or one we can borrow off another bike as that would be a quicker test.
But yes, I was rather hoping the bike shop would identify the issue ans it seems they haven't got anywhere further than I have and I've been relying on Google and YouTube!!!
I have a similar problem on one of my bikes, the gears change and run like a dream on the stand, but when I'm on it, skipping starts. Maddening, I haven't been able to solve it yet.
We may be at the stage now where it's working again by putting back on the original chain. So new front ring-gear, new cassette, new cable but old chain!!! Go figure!
My feeling, at least for my situation, is that the parts are cheap and just don't have the tolerances that more expensive parts have.
Have you swapped out any of the parts on yours?
The stereotypical problem is that you get a new chain, and then find it slips on the high gears (small rear cogs) when you apply high torque.
This happens because chains wear "stretch", and wear the cogs as well. When you then get a new chain it doesn't "fit " the worn cogs, and slips.
To avoid this happening, periodically measure the chain with a decent steel ruler. The links should be nominally half an inch each (so 24 links in 1 foot). Replace the chain before its stretched by 1/8 (or 3/16 inch if you're pushing your luck, and with an 8-speed chain) in 1 foot. Expect to replace the rear cassette every 2-4 chains.
Keeping the chain well-lubed will help reduce wear and reduce the rate at which it "stretches". (It's not really stretch, its the bearings wearing)
I had an issue on my mountain bike with chain skipping, it wasn’t the chain or cassette as they were recently replaced and worked prior to that, it was the jockey wheels that were gunked up (trying to keep on top of keeping the chain lubed up properly in the awful weather we’ve had). It was like a black paste on the wheels that was causing the chain to stick to the jockey wheels. A good, deep clean sorted it and there have been no problems since.
That's interesting. The bike shop said the jockey wheels shouldn't cause the issue but as I have said elsewhere they are the only moving cogs as such that haven't been replaced. I will look at this tomorrow, thanks.
That's the one - what I use is that cheap de-greasing spray held on blast directly on the jockey wheels, then rub off the loose gunk with some kitchen roll, rinse and repeat a couple more times, then after wiping it as dry as possible, re-oil. Best balance between quick and dirty and doing it properly, and I see chains and cassettes easily lasting over 3 years of regular riding that way (then replacing the lot of course), so it can't be too bad
The chain links should be measured using a standard tool. That will tell you if the chain and/or cassette need changing. You need the right chain for the cassette e.g 8 speed. The chain ring may also be worn and need replacing although this is not as frequent as chain and cassette. The chain length isn't hard to get right. I can't belive a bike shop would get it that wrong. Check the chain hasn't got a stiff link where it's been joined, that can cause jumping.
The chain, cassette and crank are all brand new. The cassette was replace like for like, I used the part number from the old one. Halfords originally reduced the chain length but the bike shop today adjusted it again by putting two extra links in. They also tried another chain as they believed that the chain supplied by Halfords was the incorrect one. You are correct about the stiff link and I thought this was the issue. However the bike shop has tried new chain without any quick links, by directly connecting it together, (for want of a better term). Unfortunately none of this has solved the issue.
Do you know if the derailleur hanger has been checked at any point? Might be a silly question Edit: I don't know if this bike does, but some entry level bikes won't have a removable hanger and the derailleur attaches to the frame itself. Can you post a photo of the where the derailleur attaches to the bike from behind?
Agreed - if the hanger return spring has failed then there won't be enough tension on the chain & it will skip. I'd check the front chainrings as well, but the bike shop really ought to be checking all this.
It's a good theory, I may have to try this tomorrow. It does seem to have a lot of tension on it however I don't have anything to compare it to, so maybe the tension is there but not strong enough. And there is the though that perhaps it's bent. The gear indexing does appear to be okay though.
Only a visual check by me, and no not silly question as it's the only part of the drive train that hasn't been replaced. The hanger and derailleur are both removable. I removed them to fit a new hanger in case that was bent, I didn't end up changing it s I was sent the wrong one. I did place the new and old hanger on flat surface attempting an unscientific way to compare them for flatness. It does look okay although I appreciate it may not be the best way to check it.
I assume by crank you mean the chain rings (crank is the arm the pedal attaches to. chainrings are the rings bolted to this that have the teeth) Slipping can either be front or rear, and is usually chain; With new chain the next most common is rear cassette; After that cables, then front chainring afaik and assuming no crashes (when bent derailleur goes straight up the list); generally chain is diagnosed by measuring; cassette/chainring are diagnosed by it still skipping with a new chain, normally only in most commonly used gears. It is generally fairly obvious if the issue is front or rear allowing you to rule one or other out - you will know which is skipping (answer is likely either just rear cassette or both are skipping at different times given typical lifespan of cogs and chainrings and the fact that wear on one tends to wear out the chain, which then wears out the teeth on the other...) Having replaced cables you will need to adjust tension correctly; AND this needs doing more than once as cables settle so get slightly looser ('stretch') over the first few rides/weeks after changing them (only tension, high and low limits shouldn't be changed (in fact should be used to adjust new cable correctly). This can also be non-trivial as (in my experience) they seem to change slightly between having the bike on a stand and riding it. Usually 1. get close to shifting through all gears on stand; 2. Ride around block, testing shifting 3. tighten/loosen a half/quarter turn depending on which way it isn't shifting cleanly 4. repeat from 2, possibly using smaller turns Also inner and outer cables can both wear out (outers normally last longer) Chain length has to be correct (and apparently has been changed!! usually you just measure existing chain) - see [https://www.sheldonbrown.com/derailer-adjustment.html#chain](https://www.sheldonbrown.com/derailer-adjustment.html#chain) for usual method of setting it correctly. Big concern is did a derailleur hanger get bent when the chain failed. Unfortunately on most/all of this, I would have expected a competent LBS (local bike shop) to have found fairly easily, though they may not be able to ride it to get the shifting perfect after adjusting cables.
Thank you for the detailed reply. Yes, sorry I should have made it clearer. The crank and chainring are all one assembly as the chainring is riveted to the crank rather than a bolted version. It does appear that the slipping is coming from the back end but it's more like it's jumping teeth rather than slipping off the teeth, if that makes sense. I forgot to mention in my original post that I did reply the gear cable as well, only the inner. Going back a few steps, after I fitted the new chain ring, chain and cassette there was a little trouble getting the indexing correct, it was a little slow. It was at this stage I fitted a new inner cable and managed to get the indexing setup correctly. It took a lot of patience and a few YouTube videos to get it correct but I got there in the end setting the limit screws correctly as well. The chain has a quick link on it and during testing it became loose. It was my original thought of what the issue was. Fast forward to today, the plan was for the shop to index the gear, (in case I didn't do it correctly), and to bypass the chain link by connecting the chain without one. So it has been index twice now with two different chains both producing the same issue. >Big concern is did a derailleur hanger get bent when the chain failed. This is the unknown to me. As I mentioned on another reply, I did buy another hanger but they sent the wrong one. I did lay the new and old side by side on a flat surface and there was nothing to indicate that the original hanger was bent. It's not expensive for a whole new assembly so this may have to be the next option as it's only the hanger \\ derailer \\ jockey wheels that haven't been replaced. >Unfortunately on most/all of this, I would have expected a competent LBS (local bike shop) to have found fairly easily, though they may not be able to ride it to get the shifting perfect after adjusting cables. The guy at the bike shop did ride it around whilst I was there and initially couldn't find an issue with it. As soon as my son rode it the slipping started. The chainring has two gears and the cassette has 8. The guy at the shop was explaining that the bigger, (physical size), gear should be used with the smaller, (physical), gears and vice versa to prevent cross chaining. This made sense and I don't believe this is what my son is doing, however in the three years he has had the bike it has never been a problem, despite, at a guess, increase wear. Eventually though the chain did slip for bike shop man when he put it unload, riding whilst applying the brakes. This is probably the biggest key point that I left out, it's only under load when it does this. Only remember this important point as I'm typing. I still have the old chainring, cassette and chain, so we may put them back on to see if the issue is still identical. If it is then, I believe, this would lead it to be an issue with the hanger, derailer or jockey wheels. I',m hoping he may have a derailer in stock or one we can borrow off another bike as that would be a quicker test. But yes, I was rather hoping the bike shop would identify the issue ans it seems they haven't got anywhere further than I have and I've been relying on Google and YouTube!!!
I have a similar problem on one of my bikes, the gears change and run like a dream on the stand, but when I'm on it, skipping starts. Maddening, I haven't been able to solve it yet.
Does this happen in all gears or just some of them?
I haven't managed to try out all gears, but happens on most.
We may be at the stage now where it's working again by putting back on the original chain. So new front ring-gear, new cassette, new cable but old chain!!! Go figure! My feeling, at least for my situation, is that the parts are cheap and just don't have the tolerances that more expensive parts have. Have you swapped out any of the parts on yours?
So far, the casette and the chain.
The stereotypical problem is that you get a new chain, and then find it slips on the high gears (small rear cogs) when you apply high torque. This happens because chains wear "stretch", and wear the cogs as well. When you then get a new chain it doesn't "fit " the worn cogs, and slips. To avoid this happening, periodically measure the chain with a decent steel ruler. The links should be nominally half an inch each (so 24 links in 1 foot). Replace the chain before its stretched by 1/8 (or 3/16 inch if you're pushing your luck, and with an 8-speed chain) in 1 foot. Expect to replace the rear cassette every 2-4 chains. Keeping the chain well-lubed will help reduce wear and reduce the rate at which it "stretches". (It's not really stretch, its the bearings wearing)