Changing stem on full carbon. Advice?
 

I'm about to change the stem on my Cannondale R3000, which requires removing and later re-installing the bolt in the top of the steerer tube. I've been told to use caution re-installing the bolt since the steerer tube is carbon fiber. Any advice would be appreciated.

when you are putting the steerer tube bolt back in, make sure the screw is alligned with the starfingle (the star shaped piece inside the tube of your front fork). Otherwise you may bend the starfingle out of shape and therefore unable to be used. trust me, without the right tool these things are a pain in the a** to replace.

The bolt at the top is what snugs the bearings up. It is not something that you really crank down on. The bolt on the stem itself are the ones that cause the stem to grab the steerer. they need to be nice and snug, but not gorilla tight. I am sure someone here can give you the torque spec if you have a torque wrench.

When you put the stem back on leave the stem bolts loose. Tighten the top cap down lightly. Then tighten the stem bolts. Check the adjustment by locking the front brakes and pushing the bike back and forward. If you feel movement, loosen the stem bolts, tighten the top cap 1/6 - 1/4 of a turn, tighten the stem bolts again. Test again. It may take a few tries.

If your steerer is carbon, it may not have that dreaded star-fangled nut....but something a little gentler designed for carbon tubes. In any event, you should proceed with caution any time you're clamping or tightening anything onto carbon fiber.

George

Best advice ever: Steel. Steel is Real.

I would personally avoid a star-fangled nut on a carbon steerer. Instead, consider using a compression assembly like the following:

http://www.fullspeedahead.com/produc...compressor.jpg

Also, be careful about the new stem's clamp slot and check with your fork's manufacturer to see if the stem is compatible. Some clamp designs put a stress riser in the steerer. You basically want a clamp where the slot is in line with a radial of the steerer and the bolt is perpendicular to the radial from the center of the steerer.

Cannondale recommends a star nut for its new all carbon forks. I was surprised, but the Cannondale rep confirmed it. I'm guessing that it saves 75 grams, and that may be reason enough for them to use it.

F**K that , don´t use a star . If you don´t feel confident or own a torque wrench then find a friend or lbs to do it - it´s way to easy to crack carbon and forks cost serious money so to pay a small fee .....