Thursday, September 4, 2008

Q&A: Binding Mavic Ksyrium cassette

Q: Jim - The cassette on my Mavic Ksyrium rear wheel is binding. I first noticed this by seeing that if I spun the rear wheel by hand, every now and then the chain would suddenly start being driven by the rear wheel and the pedals would turn - almost like on a fixie bike with only one gear and no coasting feature. At first it only did this once in a while, but now it's binding all the time and when I am riding the cassette tries to turn with the wheel and this creates slack in the chain and I bet additional friction at the wheel that's slowing me down! Not good on what are supposed to be my fast wheels. What do you think is wrong, and do I have to return my wheel to Mavic for service, or is this something I can fix myself?
Thanks for any help you can provide,
Lloyd

A: Hi Lloyd,
The likely problem is lack of lubrication, or some grease that has gotten congealed and is now sticky instead of slippery, right where the cassette attaches to the hub. There are cartridge sealed bearings inside and also seals. All these things need to be nicely lubed for the cassette to spin freely and not bind or drive the chain forward. I recommend visiting Mavic's tech website at http://www.tech-mavic.com/, login "mavic-com" and password "dealer" (do not include the quote marks)
Mavic's tech site has the instructions for servicing almost everything Mavic
Here you'll find manuals for all Mavic products going back years, and instructions for your specific wheel (like the diagram above). Assuming you have a few basic tools (you'll probably need a 5 and 10mm Allen wrench and a way to hold the axle, such as an axle vise - or home-made version) and a little mechanical ability you should be able to fix this problem yourself by following the directions.
For a sticky cassette, you would disassemble the hub by removing the axle with Allen wrenches and then carefully pulling off the cassette (don't drop/lose the pawl springs!). This reveals the bearings and seals and you can check the grease inside and clean and lube as necessary. Use a light and safe oil (it mustn't attack rubber or plastic) on any seals because if they're dry they can cause the binding. Then reassemble the hub and you should be good to go. Or, if you'd rather let a professional handle it, any shop that sells Mavic wheels should be able to service yours for a reasonable fee.
Happy hub and cassette repairing!
Jim

7 comments:

Andrew Overfield said...

I am having a similer problem with my Crossmax SLRs, when coasting at a moderate speed 30kph or higher, the rear hub starts to vibrate and the cassette rotates forward causing the chain to go slack. Tension returns when I start to pedal or stop the bike. Taking that wheel out tonight and taking it to a shop tomorrow.

Dave Black said...

Similar problem with 2008 CrossRide rear hub. Had been using a non-bike-specific water-proof bearing grease for lubrication (ah the joys of winter riding in the pacific northwest). Suspect that heavey grease was the source of the problem, so changed to a light synthetic bike-specific grease from Phil's. Problem seems to be resolved. Noted when disasembling a 2010 CrossRide hub (for comparison), that oil was used for lube. Can't get into Mavic tech website, but what does Mavic recommend for lubricating their cassette shells?

Jim Langley said...

Hi Dave,
Mavic says to use oil, so there's a good chance using grease is what's causing your issues. Grease might work in warm climates because the heat would thin it. But the cold makes it gum up which could cause issues in the confines of a cassette body mechanism. So, I'd give an oil about like 40W motor a try and I bet that'll work better for you.
Hope that gets you spinning,
Jim

Tim Purcell said...

Mavic says to NOT use grease. They say to use their special mineral oil at about $20 a bottle. I use Pedro's Road Rage after seeing it recommended by the Rogue Bike Mechanic. It works great. Motor oil is not a good idea. It will build up and stain aluminum.

Don't forget to gently snug up the long bolt with the 5mm hex wrench. It is easy to snap off. Don't go crazy with the torque.

Jim Langley said...

Thanks, Tim. I've heard a few people recommend Pedro's Road Rage but as far as I can tell Pedro's doesn't make it anymore. Here's a link to their lubes page and I don't see it there. http://www.pedros.com/products_lubes.htm If there's an equivalent lube in their line, I'm not sure which one it is, but I have had good luck with many oils and don't think it's critical which one you use as long as you don't use grease. I haven't had any negative issues with motor oil. Appreciate the feedback,
Jim

Anonymous said...

The real solution is to take the initial rubber ring that sits behind the freehub body OFF.

Jim Langley said...

Well, you could do that if you didn't mind voiding your warranty with Mavic (probably not applicable on an old wheel anyway) and if you plan to keep adding more lube even more frequently since the seal would be gone. But you can always remove seals with any bearing if you want to. That's an old trick going back to the dawn of cycling, but it always meant using more care to ensure the bearings stay lubed and don't dry out.
Thanks!
Jim