Rear Ksyrium Hub Locks Up, WHY?

Fhernand said:

I have a Ksyrium wheel in the back. When I pedal backwards, the rear hub is locking up causing my chain to jump off the cogs. Have you had this problem? Could it be dirt in the hub?

The MAVIC Ksyrium hubs were poorly spec'd ...

There is a plastic bushing in the freehub body which should have been a sintered bronze bushing OR a ball bearing OR anything but the plastic bushing that is being used ... this has been a KNOWN PROBLEM for at least a half dozen years.

Depending on how much coasting you do, it can fail anytime AFTER ~3,000 miles (~5,000 km) ...

Your hub probably needs to be serviced.

Alfeng, you are correct, I do lot's of coasting since I'm climbing most of the times. What poor design. Thank you.

The freehub is supposed to be stripped and relubricated every 6 months or so. Were you given any instructions regarding that? You need to do this immediately or else risk the freehub locking on a fast descent. You will also (probably) need to rebush or replace the freehub. If your hub is worn by the bush, you can buy a new bush with a slightly narrower internal diameter than the Mavic one.

I went ahead and broke down the hub. The good knews is that the freehub looks fine. The plastic bushing and inner part were fine. However, the metal "paws" the pieces that have a small spring attached.....one of the paws was broken off. I replaced it with a new one and the problem went away. Still, it's not spinning totally free. A local bike mechanic at REI told me that I will have to eventually purchase a new wheel or, send back to Mavic to the them rebuild the insides. Hum?

Friends don't let friends ride Ksryriums. The rear hub is a pretty poor design.

artemidorus said:

The freehub is supposed to be stripped and relubricated every 6 months or so.

Wow, what a piece of garbage!

Okay guru, what's your choice of wheels? ; )

Fhernand said:

Okay guru, what's your choice of wheels? ; )

Hand built wheels w/ Kinlin, Velocity, or DT rims; White Industries,DT Swiss240s, Royce, or Goldtec hubs; and for me, DT Aerolites. Almost any hand built wheel will beat the pants off of Ksyrium wheels.

Dietmar said:

Wow, what a piece of garbage!

It's not as bad as it sounds. The internals are very simple. It really doesn't take any longer than a thorough chain clean, if you are into that.

artemidorus said:

It's not as bad as it sounds. The internals are very simple. It really doesn't take any longer than a thorough chain clean, if you are into that.

Well, I'll betcha, if I take a hub from some of the Walmart bikes, it will last for many years, and many thousands of miles, without any maintenance whatsoever. My 20-year-old steel bike has a Dura-Ace hub with something like 15,000 miles on it that has never been serviced. Smooth as silk. There's no reason any hub should need more maintenance than this.

Dietmar said:

Well, I'll betcha, if I take a hub from some of the Walmart bikes, it will last for many years, and many thousands of miles, without any maintenance whatsoever. My 20-year-old steel bike has a Dura-Ace hub with something like 15,000 miles on it that has never been serviced. Smooth as silk. There's no reason any hub should need more maintenance than this.

You seem to have misinterpreted my comments as praise for the FTS-L hub common to most of the current Mavic wheels. Far from that, I agree that the hub is poorly designed and I put up with it as a necessary evil of the Cosmic Carbone SL, an otherwise reasonable aerodynamic wheel. I certainly don't think that the Ksyrium package is one that I would ever bother with. My point was simply that the necessary maintenance takes up a trivial amount of time on my bike maintenance calendar.

I am familiar with the relative virtue of more traditional hubs and I also have an 18 year old bike with a Deore DX rear hub that is as good as ever, with its freehub never having been serviced in any way. Could I easily put a cup and cone hub on my Cosmic Carbone wheel, I would do so, but it isn't worth the trouble. As the OP is currently in possession of a Ksyrium wheelset, I would suggest that he maintains it, rather than discarding it.

artemidorus said:

Far from that, I agree that the hub is poorly designed and I put up with it as a necessary evil of the Cosmic Carbone SL, an otherwise reasonable aerodynamic wheel.

Yeah, the Cosmic Carbones are really nice wheels otherwise. In that case it's particularly outrageous to fit them out with such a crummy hub.