Damaged rear Mech & chain etc

[taximan]

A few days ago whilst cycling in hilly country I rather stupidly made the mistake of changing down to bottom gear on the cassette while I was still in top gear on the front ring (big ring to big ring ) The result was the chain was jammed solid & the rear mech was pretty much destroyed. Trying to hide my embarrassment I took the bike to my LBS for repair where he fit a new Mech & replaced the chain after discovering that the original was actually too short. I took the bike out yesterday and found that the chain was slipping badly when I changed down through 6th 7th & 8th (9spd cassette) but it seemed to change up OK. I did not ask for a new cassette to be fitted at the LBS at the time because the bike has done less than 500 miles . I am thinking now that the cassette may have been damaged too, though there is nothing obvious to see. Any thoughts guys ?

 

[I like Skol]

Two things may be wrong here.

1. The indexing is out. The shop should have set this and checked it after fitting the new mech, but mistakes can happen and maybe the cables are not in great shape (again, this should have been noticed).
2. The new chain is skipping on the old cassette. 500 miles is no distance, but that could be 500 miles of neglect, or maybe your 'about 500 miles' is actually 1000 miles or more and you just don't realise?

I would discuss the problem with the repair shop. Ask them to check the indexing hasn't shifted and if this is ok they may suggest a new cassette.

 

[gbb]

Mech hanger would be a good bet. 500 miles on a cassette isnt much at all, unless you can physically see any damage, it's either the new mech needs a little more adjustment, or a bent hanger.

 

[I like Skol]

Mech hanger would be a good bet. 500 miles on a cassette isnt much at all, unless you can physically see any damage, it's either the new mech needs a little more adjustment, or a bent hanger.

Shop should spot/check that, especially considering the cause of the initial failure!

 

[taximan]

I forgot to mention, The LBS said that the hanger was bent but that he had managed to straighten it. the hanger is not a 'bolt on' but is part of the frame.

 

[I like Skol]

Steel frame?

 

[screenman]

I would say if the shop sent it back out like that the tech did not know what he was doing, did he even put a tool on the hanger or just clout it with a hammer.

 

[Mike_P]

Is not the chain length the real issue as the mech should not have jammed in the first place.

 

[taximan]

Two things may be wrong here.

1. The indexing is out. The shop should have set this and checked it after fitting the new mech, but mistakes can happen and maybe the cables are not in great shape (again, this should have been noticed).
2. The new chain is skipping on the old cassette. 500 miles is no distance, but that could be 500 miles of neglect, or maybe your 'about 500 miles' is actually 1000 miles or more and you just don't realise?

I would discuss the problem with the repair shop. Ask them to check the indexing hasn't shifted and if this is ok they may suggest a new cassette.

Thanks for your reply. I will be contacting my LBS tomorrow to see what he says. As for the 500 miles mentioned, I have just totted up my diary and find that I have actually only covered 350.7 give or take a few yards and it has certainly not been neglected other than the aforementioned gear change

 

[taximan]

Steel frame?

Yes

 

[I like Skol]

Cassette should be fine then. Ask the shop to check it over again, sometimes things do not quite work spot on at the 1st attempt. I would give them a reasonable chance to correct the fault before starting to question their ability or professionalism.

 

[Gunk]

Is not the chain length the real issue as the mech should not have jammed in the first place.

On some mountain bikes it’s diffIcult to avoid this, you don’t want to run too long a chain as you get loads of chain slack when running downhill. So it can be an unfortunate compromise.

 

[roubaixtuesday]

I'd recommend going through rear mech set up as per

https://www.parktool.com/blog/repair-help/rear-derailleur-adjustment

Even if you can't get it to work, it will give you a much better understanding as to what might be the issue if you then have to take it back to LBS.

As an aside, the story vividly demonstrates the importance of making sure a chain is long enough to run big/big, even if you've no intention of ever using that combo.

 

[taximan]

I'd recommend going through rear mech set up as per

https://www.parktool.com/blog/repair-help/rear-derailleur-adjustment

Even if you can't get it to work, it will give you a much better understanding as to what might be the issue if you then have to take it back to LBS.

As an aside, the story vividly demonstrates the importance of making sure a chain is long enough to run big/big, even if you've no intention of ever using that combo.

That's a lesson I learned the hard way

 

[roubaixtuesday]

That's a lesson I learned the hard way

As a total div myself, I feel your pain.

https://www.cyclechat.net/threads/i-am-a-total-div.261149/#post-5994861