Help with a rear derailleur or wheel problem

LukeDanckert

I was out on my winter bike today and whenever I was freewheeling down hill at about 30mph and above my bike was making a terrible noise, a bit like a brake pad being applied and it screeching. I checked it everytime I got the speed up down hill and it wasn't the brake rubbing, but the rear derailleur arm moving forward and creatimg a lot of slack in the chain. This only occurred when I freewheeled not when turning the pedals forward. If I moved the pedals backwards it exaggerated the noise and forced the chain off. The noise could be from the cassette area I think.

Does anyone have any idea what the problem could be? The Mavic Aksium wheels are less than a year old and not had many miles so it seems early for a bearing problem?

Any help is appreciated.

Luke

PeterG

If the freewheel is free to turn and everything is in correct alignment then it sounds like a dry/dirty/un-lubricated chain which will bind on the cassette/mech when turning the cranks backwards when stationary.

Senecio [Daniel D]

From your description sounds like the bearings in the freehub. Though a dirty chain is another and good explanation.

LukeDanckert

Peter, cheers for the reply. Could that still be the case even if the noise and friction occurs without any movement of the chain or pedals?

LukeDanckert

Cheers Daniel, worth fixing or just a new wheel? I cleaned the chain this morning before going out.

Senecio [Daniel D]

Some hubs you can service easily, for example Campag. I've had disaappointing experience servicing Mavic wheels but have never dealt with a freehub.

Andrew R

I have serviced the freehub on my Mavic R-SYS wheels after a particularly wet experience and it was quite straightforward.

There's lots of help available on the internet.

LukeDanckert

Cheers for the tips. I'll get onto it.

tduckett

From your description its a freehub problem. The chain is going slack because of a lot of friction in the pawls of the freehub. If you take the wheel out the freehub will be stiff to turn. It could be the bearings but might just be rust and rubbish in the pawls. Get some lube in there and you should be good.

LukeDanckert

Cheers Tim, much appreciated, I'll have a go today.

Senecio [Daniel D]

I think the pawl/bearing assembly might be one unit with Mavic, from the illustration I am remembering it looks at least possible it was a replacable item.

phil k

luke

i had a mavic ksyrium wheel rim split late last year and the wheels were approx 18mths old - took them back to grafham cycles where i had purchased them, who sent them to mavic who replaced the rim free of charge and it only took 3-4 weeks, which i think is great customer service.

Rather than trying to fix the problem y'self and being mindful that they are less than a year old perhaps you could take them back to where you got them and ask that they sort it out with mavic or even contact mavic and see if they can do anything for you

phil

LukeDanckert

Cheers for the help. I'm going to get it cleaned and greased up today removing the cassette. I'll see how it looks and if it still has issues I may send it back to the shop, just a bit of a pain as I bought them in windsor when I had an issue on a previous trip!