Gear slipping/crunching/making me look a twat

Juddlinski

Just got my bike back from a yearly service from those lovely people at Evans. Only thing is, some of the gears crunch/skip/jump when I put my foot down.

So no problems changing gears , it's just that when I'm on a certain few, and put some weight on, it skips/crunches. You know what I mean. I try and pull away at traffic light and %#Clank!&@ It jolts and I nearly fall off.

it is the lower front chain ring - the top half of the gears on there.

:oops: Apologies for being so clueless, but what should I do? Rear derailleur?

desweller

So, if you've paid for a service and it worked before you took it in, you take it back and either demand your money back or make them fix it.

supersonic

Did Evans fit any new bits?

bucklb

Sounds like they've replaced a worn chain, but not the cassette.

I replaced my chain at the weekend & got similar symptoms to yours - the chain basically slipping off the cassette teeth. Does the chain look shiney & new (and the cassette look less so)?

Juddlinski

bucklb - you're spot on. yes, they replaced the worn chain , but not the cassette.

I'll go back to Evans then. which will be a major ball-ache cos its not exactly local :twisted:

bucklb

Disappointing that they didn't take it round the block to road test it, as it's an obvious thing to check when swapping a chain.

Hope it goes well

Juddlinski

actually one last question.

The bike is a year old, so I'm pretty certain the cassette is in good nick...

So it the solution a new chain that fits?

I don't need to get a new cassette, do I?

bucklb

Bottom line is if the chain is worn then the cassette wil be starting to show some signs of weaar.

The wear will be a function of mileage rather than age. I get about 1,500 miles from a chain, which isn't brilliant, and a cassette lasts 2 or 3 chains (I really can't recall, but I suspect/hope it's 3). Replacing the chain extends the life of the cassette, and also your chain ring, so is well worth doing. You might want to invest in a chain wear tool that will allow you to see when your chain is starting to wear; they can be had for around £5.

If you've used the same chain & cassette for a significant mileage (say 4,000+ miles) then it's quite likely the cassette will be worn and need replacing. I'm covering about 7,000 miles a year and planning on 5 chains & 2 cassettes a year (I have an 8 speed setup and chains cost about £10, cassettes about £10 (sram pc870 & shimano hg41)). The chain is a doddle to swap, as it uses a powerlink. Cassettes aren't hard to change but do need a couple of tools - a chain whip and a cassette tool, but each should cost less than £10. If you plan to do a lot of miles a bit of DIY could saave you a packet

keef66

Bottom line is if they've fitted a new chain and it now skips, chances are the cassette's worn too. If you were doing it yourself, options at this point would be:

a) put the old chain back on and run both chain and cassette into the ground together

b) fit a new cassette and resolve to start checking chain wear more frequently.

I suspect a) is no longer an option as they will have binned the old chain, and anyway that approach would also start to wear the chainrings which might be dearer in the long run.

New cassette time I think.

Juddlinski

Bucklb, Keef - many thanks! Appreciate the advice.