Bicycle Accidents caused by broken carbon steer tubes

A small group of road racers have recently broken the carbon steerers on their 2010 Trek Madone 6-Series bikes. Of all things to fail on a bike, nothing can be more fatal than a steer tube. So the question becomes, is it incorrect stem installation, incorrect stem choice,
or the fact that Trek 6-Series Madone steerers are prone to breakage even when all of Trek’s instructions are followed?

As you would expect, 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. All owners of forks with carbon steerers should pay attention to the concerns raised and installation instructions when installing or buying aftermarket stems.

If as Trek alleges the problems lie with improper installation or incompatible stems, then the onus is on the Bicycle shop and mechanic to be aware of these issues. To that end, I have dealt with shops that are truly aware of problems and take safety very seriously, and also had the misfortune of shops that are just concerned with a sale, and do nothing in terms of education about safety issues.

On Saturday May 15, 2010, Bryan Vaughn was on lap 4 of the Poolesville Road Race when he pulled up on the bars of his 2010 Trek 6 series Madone,and felt the handlebars come off in his hands as he crashed to the ground. One can’t help but imagine the feeling of horror Bryan felt with the bars in his hand and no control over his bike as steerer had sheared off just below his FSA stem.

The next week, one of Vaughan’s teammates stood on the pedals of his 2010 6-Series Madone to pull away from the start line of the Bike Jam Pro/1/2 criterium in Baltimore. His bar and stem suddenly separated from the bike and he crashed, although at a much slower speed than Vaughn. As with Vaughan’s, the steerer tube had sheared just below the stem.

Thereafter, another incident when Paul Wilson’s steer broke during the Wilmington (Delaware) Grand Prix on May 22, 2010.

Riders on another Trek-sponsored team told him they had experienced two steerer tube failures in just one weekend in April.

As a Florida bicycle accident attorney I handled a number of cases involving forks that broke on mountain bikes. The manufacturer in those cases denied liability, and thru the work of experts we were able to establish that the fork manufacture was negligent in their design and production of the forks.

Asis the case with most corporations these days, expect Trek to admit nothing, and continue to point the finger elsewhere. In the interim, take your bike to the shop for a thorough inspection.

According to Trek, there are three keys to safe and successful installation of a stem on a carbon steerer:

1) Always use a torque wrench, and never over-tighten stem clamp bolts.

2) Always use spacers above and below the stem. Although less obvious than correct torque, a minimum of 5mm and a maximum of 40mm spacers under the steerer, plus a 5mm spacer above the stem are required. Riders should factor in these spacers when sizing their bike.

3) Use only the stem brand and model that came with the bike, because not all stems will work with carbon steerers. Often the lighter the stem, the less chance it will be compatible with a carbon steerer. Weight-relieving cutouts on the stem clamp and steerer interface can create stress risers.

Vaughan’s FSA stem was incompatible with the steerer, Trek said.

FSA isn’t convinced they’re to blame and points to poor installation as the more likely culprit. “To say that it’s not compatible is a little odd to me,” said Max Ralph, FSA marketing manager. “There are lots of stems on the market that are designed similar to ours.”

And the blame game will continue.