Last chance to save my bike...

I have a Reebok Apex bike - 21 speed. A few weeks ago, the rear gears started to 'clunk' when pressure was applied to the pedals. From looking at the rear mech. when the clunking occurs, it looks as if the chain wants to move down to the next smallest sprocket. I took the bike into the shop, where the guy has replaced pretty much all he can - rear derailleur, chain, pedals, cranks, chainring, and cabling. Even after all of these parts have been fitted, and the gears have been properly adjusted, they still 'clunk' upon pedal pressure. I personally have swapped the cable and outer casing to eliminate that, to no avail.

We are now at the last part we can think of to replace: the cassette. He's ordered the part, and it should be in within the next few days, which hopefully will fix the problem.

My question: does anyone have any theories as to what could be causing this problem, and do you think the cassette will fix it?

Many thanks in advance,
Fraser

 

A 21 speed very well may have a bent or broken axle although I am not sure if that would have any bearing on your problem. How old is the bike?

Does the crank seem to skip ahead when you hear the clunk?

 

Is the cassette worn? I'm surprised the chain and cassette weren't the first things he thought of.

 

That's what I was thinking. The chainring....maybe, if you have a lot of miles on it. But the rear derailleur, pedals, cranks, and cabling before the cassette and/or chain????

 

I would have thought the first thing to try, after looking at the chain and the derailleur would have been the sprockets - whether they be on a freewheel or a cassette. I'm surprised he hasn't thrown another back wheel in there and tried it.... That would have been a two minute test.

I'd change bike shops to be quite honest. It was nice of them to sell you some pedals when it looks like the chain is jumping...

 

Pedals.....interesting. Maybe the thought was with a different, assuming wider, platorm, you'd be able to pedal so fast that between exhaustion and cardiovascular decompensation, you wouldn't even notice the chain skipping.

Did they try to sell you a Fetzer valve?

 

Before we go any further, I'm just going to clarify that while the bike is around 2.5 years old, the only new part that I have paid for was new bearings at £4.99, which I forgot to mention were replaced too. I know the guy well, and let's just say he's doing me a favour by claiming the parts under warranty, because the bike's hardly ever been in.

He did have a look at the cassette first, but there didn't seem to be any apparent signs of damage. The only reason that all the other parts have been replaced first is because he was having trouble getting in contact with the supplier.

Yes. I've almost hurt myself testing the thing after the all the new parts... Hopefully the cassette should be in soon - if it hasn't already arrived, I'll phone today - and I'll mention the suggestion of trying another wheel. Hopefully he'll have one of those in the store...

 

The shop should be road testing the bike before handing it back to you!

 

My apologies, I didn't make this clear when I spoke about testing the bike. The guy from the shop does test the bike out in the car park before allowing me to test it. We often find that the problem is more severe when he's testing it as opposed to myself, and at the end of the day, I'm the only one who uses the bike.

 

This is the classic symptom of a worn cassette.

Actually I think a 21 speed, newer bike would have a freewheel rather than a cassette, not that it changes anything.

 

Hopefully that should turn out to be the solution then. What I find quite strange is that the clunking only occurs in certain gears - I was able to cycle into town for my lunch this morning, using only 8th gear (2nd on front der., 4th on rear) without any trouble.

Another thing that might be worth mentioning is that the problem is most prevalent when the chain is on the 3rd sprocket at the rear.

I phoned the guy earlier this afternoon, and the part hasn't yet arrived. He said he'll give the supplier another phone as soon as he can.

Thanks for all the replies so far - I'll keep you posted.

 

It's not the freewheeling mechanism which is worn, it's the sprockets themselves. It only happens in certain gears because those are the worn out ones.

 

That's been the case since all the new parts have been fitted, but it used to clunk on pretty much every gear. After the new chain was fitted, it would clunk on most gears, so the guy removed a couple of links, which caused an improvement. Clunking was still common on two or three gears, so he took out another couple, which narrowed it down to the one main sprocket (although it very occasionally clunks under pressure on other gears, but not as much). Taking any more links out would make the chain too small, so we're counting on this final part to solve the problem. Simple question - yes/no answer - do you think this will be the solution?

And hey, if it does fix it, I've still got all those brand new parts for only £4.99!

 

After a long wait for the supplier to deliver the new cassette (I've also been away on holiday hence the long time to post), the problem's been solved.

Thanks to all who replied.

 

I think this bikeshop is at it; I'm with the previous poster's suggestion of changing bikeshop. What really gives it away is the fact that the bikeshop replaced the chain without even taking a second glance at the cassette. Even the most dumb of wrenches would know that these tend to wear hand-in-hand. Replacing the pedals is just ridiculous. You can bet your bottom dollar that the cassette will fix it - after you've been sold a new water-bottle cage.