Slipping gears- help please!

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rph112233
Posts: 12
Joined: 30 Jul 2021, 4:35pm

Slipping gears- help please!

Post by rph112233 »

Hi there, the gears are slipping on my bike when I shift into 5th (on the rear) and above.

I have recently changed the chain, the cassette, the rear derailleur and the chainwheel (Shimano Altus chainset) trying to sort this problem but the gears are still skipping and its driving me crazy!

I usually do all the repair and maintenance work myself, but out of frustration, I took it into a bike shop in Hackney Wick for advice, and he glanced at it for half a second and told me it was the chainwheel before trying to book me in for a replacement.

I changed the crank myself today and I have exactly the same problem.

All the gears change perfectly, so it seems to be set up ok, but every time I go above fifth gear the slipping starts.

Please help a very frustrated cyclist before I throw this goddamn bike in the canal and put my car back on the road!!!
Jdsk
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Joined: 5 Mar 2019, 5:42pm

Re: Slipping gears- help please!

Post by Jdsk »

Welcome.

That's a vast amount of replacement.

Have you realigned everything from scratch?
https://sheldonbrown.com/derailer-adjustment.html
https://www.parktool.com/blog/repair-he ... adjustment

Jonathan
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fausto99
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Location: NW Kent

Re: Slipping gears- help please!

Post by fausto99 »

Very difficult to know what you mean by "slipping" - Can you post a video on YouTube? (a slotted chain and toothed cogs can't actually slip)

"5th and above" - how many cogs do you have on the back?

What do you mean by "above"? a higher gear or a bigger cog?
rph112233
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Joined: 30 Jul 2021, 4:35pm

Re: Slipping gears- help please!

Post by rph112233 »

The bike is 18 years old and has done about 25,000 miles (I estimate) so the new parts were needed as the old stuff was fairly worn out.

As I said, all the gears change fine and I have been tinkering with limit screws and barrel adjustors trying to improve things, but don't seem to be able to stop the slipping, which only happens from 5th and above. I have even taken the derailleur hanger off and re-seated it, with no improvement.
rph112233
Posts: 12
Joined: 30 Jul 2021, 4:35pm

Re: Slipping gears- help please!

Post by rph112233 »

fausto99 wrote: 30 Jul 2021, 5:02pm Very difficult to know what you mean by "slipping" - Can you post a video on YouTube? (a slotted chain and toothed cogs can't actually slip)

"5th and above" - how many cogs do you have on the back?

What do you mean by "above"? a higher gear or a bigger cog?
It only happens when cycling, so difficult to video! It doesn't change gear when slipping, it just slips!

It is an 8-speed bike, the slipping occurs when going up in gear (or to a smaller rear cog).
TheBomber
Posts: 520
Joined: 16 Feb 2020, 8:18pm

Re: Slipping gears- help please!

Post by TheBomber »

Stiff link in the chain? How did you join it - with a quick link or by driving the rivet in with a chain tool? If you watch the chain going round the sprockets while back pedalling it should be obvious if this is the cause.
rph112233
Posts: 12
Joined: 30 Jul 2021, 4:35pm

Re: Slipping gears- help please!

Post by rph112233 »

Hi, I replaced the chain a few weeks ago with one I bought off eBay and it had about 15 stiff links in it that I couldn't get rid off, so I chucked it and bought a new one from Halfords.

The new chain, using a Clarks quick link, works perfectly. No stiff links or juddering at the derailleur.
nichog
Posts: 28
Joined: 2 Jan 2013, 11:52pm

Re: Slipping gears- help please!

Post by nichog »

Slipping in the higher gears means the drive can’t cope with high torque and the chain is jumping over the teeth. (If the gears don’t make horrible noises then it sounds like it’s all aligned sufficiently well - nothing’s really aligned on a derailleur set up!)
Is the chain sitting down in the teeth properly? Eight speed chain is the same as 5,6 and 7 speed. (All Shimano system chains have the same internal dimensions it’s the external width that reduces on 9 and 10 speed)
Is all the replacement stuff you’ve bought all the same system? Can you feel or hear where it slips - front or back cogs?
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Paulatic
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Re: Slipping gears- help please!

Post by Paulatic »

Is the chain the same number of links as the original?
Could be too long and loosing tension.
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rph112233
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Joined: 30 Jul 2021, 4:35pm

Re: Slipping gears- help please!

Post by rph112233 »

It feels like it slips on the rear cassette, which is the only component that is not Shimano Hyper Glide (Altus m510 rear derailleur and M511 chainwheel).

I bought the cassette (https://www.decathlon.co.uk/p/12x32-8-s ... R-p-100587) from Decathlon and it is their own brand. I cannot see any wear on the cassette and it is less than 2 months old. I guess the next step will be to take the cassette off and try and re-fit it, and failing that to replace it, but so far I have spent an awful lot of money I cannot afford on a bike that is worth about £75!

Re. chain length: I have no idea how many links were in the bikes original chain, but surely the derailleur should take up any slack regardless, unless it was outrageously too long, which is unlikely for an 8-speed chain?
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Paulatic
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Re: Slipping gears- help please!

Post by Paulatic »

If you don’t know what the original number of links were then loop the chain over the biggest ring and biggest sprocket. Not going through the derailleur and then add two links.
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esuhl
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Joined: 22 Mar 2017, 3:20am

Re: Slipping gears- help please!

Post by esuhl »

rph112233 wrote: 30 Jul 2021, 6:02pmRe. chain length: I have no idea how many links were in the bikes original chain, but surely the derailleur should take up any slack regardless, unless it was outrageously too long, which is unlikely for an 8-speed chain?
I've only used 9-speed chains, but every one I've ever bought has required shortening.

If you google "chain length calculator", you can probably find out how long your chain needs to be. Try the method in the previous post as well, and they should be identical.

Also, check the B-tension screw. On my bike, there's a metal tab on the derailleur that needs to be rotated so the B-screw pushes against the tab, and the tab pushes against the mech hanger. It's possible to rotate the tab out of the way so the screw directly pushes against the mech hanger, which might cause problems..
Last edited by esuhl on 30 Jul 2021, 7:51pm, edited 1 time in total.
rph112233
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Joined: 30 Jul 2021, 4:35pm

Re: Slipping gears- help please!

Post by rph112233 »

I think the chain I have has 114 links, but I acquired a chain tool during this maintenance trauma, so I will knock out a few links tomorrow and see if it helps! Thanks.
colin54
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Re: Slipping gears- help please!

Post by colin54 »

I had a similar problem recently, it turned out to be a sticky gear cable caused by crud in the bottom bracket cable guide and general non smooth running through the outer cable, I replaced the inner and outer cable and order was restored. I even changed the cassette before I found the real problem.
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SimonCelsa
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Re: Slipping gears- help please!

Post by SimonCelsa »

rph112233 wrote: 30 Jul 2021, 7:46pm I think the chain I have has 114 links, but I acquired a chain tool during this maintenance trauma, so I will knock out a few links tomorrow and see if it helps! Thanks.
I'd be a little bit more methodical than that, you could trash something quite badly if your chain is too short and you inadvertently put the transmission in big ring - big sprocket...........big bang!!
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