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Cranks slipping forward
I went for a ride this morning where I had this horrible kind of slipping when pedaling under load. At first i thought it was the rear derailleur slipping between gears but it was definitely not that. It was kind of as if it was slipping forward as I was pedaling and not "catching" properly, each time I did it it made a very unhealthy clunking sound. It occurs no matter what gear I am in and what cog I am on so I have discounted that. I had someone watch as I pedaled under load and they said that they could not see the chain obviously getting caught anywhere or skipping between gears/cogs.
Kind of vague explanation but any assistance would be greatly appreciated.
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Only a guess here, but thinking it might be your chain slipping on your rear cassette.
Have you just put a new chain on an old cassette?
If not, have you how many kms have the current chain and cassette done?
When chains and cogs wear you tend to get a very obvious skip because its a big movement. It also makes a lot of noise. When a Freewheel has had the carrot it will only slip a tiny bit. It's more common that it will stick than skip but it sounds to me like your pawls have bent or warn out. I would get a friends rear wheel and give that a go with your casset on. if you cant swap cassets just give it a go with another wheel and if there is no skip than I would say you need a new rear hub. Unless it's a really good quality one, the internals are almost never worth replacing.
I have busted a few hubs doing trials
My freehub body behaved a bit like that when it broke a few teeth. It would only do it in certain places, which happened to be most of the time. Only takes a few minutes to replace.
http://www.sheldonbrown.com/k7.html
http://bicycletutor.com/freehub-body/
Are you on a specialized by any chance? Anyway sounds like the crank arm is loose.
I've got a couple of mates who have just put on new chains on old rear cassettes and they both now complain of slipping (and they both happen to be specialized - although I wouldn't thought that mattererd?) - Is this the norm then? Should you change the chain every 6 months to avoid this?
If you change the chain before it stretches too much you can get 4 or 5 chain per cassette/rings
There are several chain stretch measuring thingies or you can measure out 12" from the centre of a pin and you should be in the centre of another pin. Any more than about 1/8" out and it's gone too far
Your mates are best to put the old chain back on and ride it until every until the spockets are too worn to grab any more and then replace chain, cassette and chainrings all in one go
It sounds like the cassette needs replacing. I have been through a few chains, mainly because I tended not to be very "nice" to them and they needed replacing. I did just put on a brand new chain, the first ride with it was fine and then yesterday's debacle. My first stop will be the tighten the crank arms but I think that they are ok. Am I correct in saying that I just need to buy a new cassette (and perhaps chainrings as well) as that includes the freehub?
Just the freehub. If your cassette is OK and your chain is ok you only need to replace the freehub. Same thing happended to me on my old bike,
slips at the worst time under load and you nearly lose the family jewels on the stem.
Thanks Steve. Does that mean that I can just replace the freehub body or am I really looking at the entire freehub, i.e. moving spokes, rims, etc. over to a new freehub? The chain is fine and I just had a good look at the cassette and chainrings and they don't look too bad at all. I am tempted to take the whole thing to the LBS in the interests of getting back onto it ASAP but I am enjoying working on the bike and at l;east like to know what I am likely in for/the amount of work involved.
While we are speaking of freehubs......
Does anyone here bother to clean/lube Shimano freehubs?
If so, what do you lube it with i.e. grease, oil or a combination of the two?
Is it worth getting a "freehub buddy"?
Any other comments? (Don't say buy something else!)
From memory was about eighty bucks and took them no time at all.
Easy DIY
http://www.parktool.com/repair/readhowto.asp?id=45