dirtydozen

Hello,

I did a couple of climbs 2 weeks ago and during the descents my freewheel would make a weird noise (like a very noisy hub).

It doesn't happen systematically when I am in free wheel, I can spend 10sec and then noise comes, sometimes noise comes just after 2 seconds as well.
What is consistent though is :
1) as soon as I pedal the noise is gone instantly
2) if I pedal backwards it makes the same noise instantly and i can feel it's not smooth

Do you guys have any ideas what could be the reason ?

thanks

eduskator

It's hard to say without a video / sound clip. Also, what do you mean by ''its not smooth''?

My freehub sound isn't always constant either (it changes depending on a few factors, including the temperature) but I don't feel like there's anything wrong with it.

datlas 

Probably one of the pawls in your ratchet is stiff and/or needs lube. I suspect plenty of YouTube videos explain how to disassemble and grease this.

frdfandc

Need to know what kind of sound it makes to try and pinpoint what's going on. A video or sound clip would be very useful.

Chandne

Pull the cassette off and take a look. It may need a good cleaning and some grease but make sure nothing is broken.

choddo

Does the top of the chain go slack when this happens, as if the cassette is being pushed forward a bit by the rotation of the wheel?

Is it a Mavic wheel?

aliasfox

I had this happen on my old Mavic Ksyrium Equipe. First time, the wheel freewheeled much more loudly than before, like something snapped inside the freehub and was buzzing every time it freewheeled. It eventually started taking longer to engage (think more than 1/4 turn of the cranks, maybe a full revolution before it engaged). Took the wheel to the shop, they diagnosed it as a failing freehub, and put on a working freehub from another Mavic that had come in (for the cost of labor). The 2nd freehub started failing a few weeks ago, with the symptoms you described - upon coasting, the top of the chain would go slack, and even a small amount of backpedaling (2-3 rotations) would cause the chain to go slack enough that the bike would try to shift gears. As this was already the 2nd freehub, and the rims were pretty worn down, I bit the bullet and bought new wheels. Ksyrium S wheels this time, no complaints so far.

Iride01 

If the top run of the chain isn't going very slack, then I'd tend to not worry about it. Probably you just have a noisy hub that gets noisier and changes sounds somewhat as you get faster. Maybe the lube is getting pushed more out of the way and isn't cushioning the pawls every blow they make in the rachet mechanism.

If it's a problem that is about to happen, then you'll probably be able to realize exactly what needs fixing when it becomes very evident to you for the same amount of money or less than you can "fix" potential causes.

big john

Could be freehub bearings.