Racers are increasingly concerned over carbon steerer tube breakage on their Trek Madone 6 series bikes. Trek says installation and compatibility problems are at fault and notes that the same concerns apply to carbon steerers from other manufacturers. The company is working with the Consumer Product Safety Commission on a consumer alert, and has made a running change to add material to 6-Series Madone steerers.

Here are 3 issues to remember when clamping a stem to a carbon steerer tube:
1. Use a torque wrench. Always and every time. As with any carbon part, over torquing the stem clamp around the steerer will compromise the carbon structure. This is not a new issue and most racers understand this. But the consequences of over torquing a carbon steerer are real and can be catastrophic.

2. Use spacers above and below the stem- always. This is not as obvious as over torquing, but riders must have a minimum of 5mm and maximum of 40mm of spacers between the stem and the headset. In addition, a 5mm spacer is required above the stem. These spacers prevent the stem from creating a stress riser on the steerer. Racers must factor in these spacers when sizing their bike.

3. Use only the stem brand and model that came with the bike. This one is a little tougher for most racers as we understand the desire to go lighter, lower or longer with their position. But not all stems will work with carbon steerers. In fact, the lighter the stem, the less chance it will be compatible with a carbon steerer. The maker of the carbon steerer can only assure the compatibility of the stem they spec on the bike. This is reality. Therefore, the only safe approach is to stay with the stem brand that shipped with the steerer.

If racers neglect any of the above, the chances of a carbon steerer tube failure are real.

Read more: http://velonews.competitor.com/2010/06/photos/carbon-steerer-breakages-statement-from-trek-bicycle_121417#ixzz0rasMopl4

The bottom line…when dealing with today’s modern materials, have a professional mechanic that has the proper tools work on your bicycle. Gone are the days when a home mechanic with a basic set of tools from the hardware store can work on their high end bicycle.