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)

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

Q&A: Remove Crankarm, space-age gearing, chains & cogs

Q: I purchased a 70's vintage Puch mostly to tinker and learn some bike repair. The Puch has a crankset with a square-spindle on the bottom bracket. The arm is not attached by a bolt but by a nut which is threaded onto the end of the spindle. The threading protrudes to the extent that the crankarm removal tool I have will not allow me to thread it into the crankarm. Do you know where I might get a tool that will do the job? Other advice?
Thanks,
Mike

A: It sounds like you need a different crankarm remover, Mike, one where you can remove the threaded plunger that pushes on the end of the bottom bracket spindle. Most bicycle shops should have these tools for sale or you could try www.bicycletoolsetc.com But, in the meantime, the easy way to get your crankarm off is to remove the nut and simply ride around your neighborhood. Don't go any farther than you want to walk home - and pedal gently. You want to loosen the arm, not have it fall off. If it gets too loose and you keep riding on it, you can damage the soft aluminum inside the crankarm because the bottom bracket spindle is steel and it will cut into the aluminum under strong pedal pressure.

Usually, a little riding will make crankarms loosen up quickly. If not, you could speed the process by spraying a penetrating lube like WD-40 in between the crankarm and the bottom bracket axle. That should do it!
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Q: Jim - I was wondering why bike manufacturers haven't produced a rear cog (gears) that expands and contracts as opposed to one that shifts from small cogs to large cogs. It seems such a design would save a lot of weight since there'd only be one cog and maybe even allow for greater acceleration since the chain would always be in contact with the same cog.

Just a thought,
Dan

Q: Thanks for the question, Dan. Actually, drivetrains like you describe have been invented over the years. The most recent design like this that I know about is on a bike made by Ellsworth. The ingenious drivetrain is called NuVinci. Here's a link where you can read all about the technology behind the drivetrain: http://www.fallbrooktech.com/NuVinci.asp Note that they use balls instead of a cog but the principle is similar. I've ridden one of their bikes and it's a unique experience and very fun. This design adds a lot of weight which is often a problem with these designs, but it's sure cool, and it works nicely.
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Q: Enjoy your site, Jim. I have a quick question. I've read that every time you change your chain, due to stretch, that you should also change out the cassette. Is this true or could I make the cassette last longer by changing out the chain more often (1/16" stretch vice 1/8").
Thanks,
Robert

A: Thanks for the question, Robert,
The cassette will definitely last longer if you replace your chain more frequently, in effect, well before it wears enough to wear the cassette too much. What happens is as the chain wears it also wears the cassette, and the more the chain is worn, the worse the wear is on the cassette cogs. So, if you install a new chain every 1,500 miles or so, you'll get more mileage out of your cassette.

I'll let you do the math, though. The decision is whether to simply ride the chain and cassette out together and replace both at the same time paying for the chain and cassette; or whether to install several chains before replacing the cassette. With the price of certain chains you may decide you'd rather just buy one chain and cassette as needed rather than going through lots of chains to extend the life of your cassette. Keeping the chain and cassette nice and clean and lubed will help a lot, too.

Some argue that the shifting is better and the chain is stronger and less likely to break if you keep it new and that may be true depending on how hard you ride or race. On my training bike I generally ride the cassette and chain out together and don't worry much about it. On my race bike where I want every possible advantage and where I run an expensive Dura-Ace cassette, I change the chain earlier to try to get a few more miles out of that way-expensive cassette. On my training bike I go with the much cheaper 105 10-sp cassette so I'm not that worried about it.

So, I agree with both schools of thought but exercise them according to which bike we're talking about.

Also, I don't agree with the blanket statement that every time you change a chain you need to change the cassette. It all depends on how worn the cassette is. Assuming the chain and cassette are both worn, then yes, you may need both. But, if you have a bike with a worn chain but a cassette that's not that worn, you can sometimes get away with a new chain. And, if you put a new cassette on a bike with a worn chain that will work, too. Not perfectly, but often good enough that you wouldn't know the difference. I just mention that because I don't like it when mechanics insist that you have to buy more than you really have to.