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I have noticed there's some friction in my free hub on the TCR - when I pedal backwards slowly, I can get the rear wheel to roll backwards (while on the stand). This strikes me as a bad thing - means when I'm coasting on the bike, I'm losing more speed than I should be.

Is there anything I can do to fix this? Is this something I should take to my friendly LBS and have them take a look, or is it something I should be able to handle at home?

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4 Answers 4

up vote 5 down vote accepted

That bike has Mavic Ksyrium hubs, and at least one person has had noise and friction issues with one.

On the other hand, they are known for their quite aggressive freewheels so you may just be hearing the loud clicking and feeling the slight friction that results. The solution is not to freewheel if you're in a hurry. Using oil instead of grease in the freewheel might help, or it might not. Weakening the springs, using heavier grease and grinding down the freewheel pawls might also work but the risk of having a nasty accident when it fails is quite high.

If it really bothers you a different freewheel (if you can) or wheelset are the real solutions.

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My Ksyriums do that, and have done for the last 5 years. They still work fine, so I wouldn't be worried about them breaking.

I have on a couple of occasions taken the hub apart and cleaned an re-greased the palls and all bearing surfaces. This seemed to reduce it slightly.

I would not recommend any changes to the internals of the hub, other than cleaning and lubricating. The consequence of a hub failure at speed are quite bad. The amount of drag you are experiencing is quite small. It's not worth risking that crash for that tiny gain.

If you are racing, and that tiny amount of drag really is the difference between win/lose (or, as in my case, between being dropped and hanging on the back. ;-) ) then you might consider second "racing" wheelset. If you do that, I recommend ceramic bearings.

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How often do you coast when you race? –  Benson Mar 2 '11 at 12:13
    
Any time I can :-) –  bh01 Feb 22 '12 at 4:22

This means the rolling resistance of your wheel is smaller than the friction resistance of the free hub. On really good hubs, this is expected, because the free hub latch actually slides on the casing, and the rest rolls.

Congratulate yourself on the quality of your hubs, and go on biking happily.

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Mavic wheels have three bearings -- one of the bearings is just for the freewheel. If you're experiencing really bad drag from the freewheel, it's possible this bearing needs to be replaced.

Tearing apart the freewheel is not terribly difficult, but if you don't have a nice space to work in it could be kind of a pain. For comparrison: when you replace a casette, you're about halfway to the wheel bearings.

If you do decide to do it, I would recommend cleaning everything as much as possible, and then re-greasing it. The trick with grease is to use a very small quantity. It's really important to keep things lubed, but excess grease can be a source of friction. I do think it's important to use grease rather than oil, because grease will protect the parts from water and dirt more effectively than oil will -- just be sure to use a very thin film of grease, and you're good to go.

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