A snapped steerer tube in the shop last week made me change how I check carbon parts

I used to just give carbon steerers a quick look and a tap test. That changed after a customer's bike came in with a clean break right at the stem clamp. It was a 2021 model with maybe 5,000 miles on it. Now I use a bright light and a dental mirror to look inside the tube for any cracks or crushed fibers, especially after any crash or stem adjustment. I also check for any weird sounds when I tighten the stem bolts. Has anyone else found a better way to spot this kind of hidden damage before it fails?

3 comments

3 Comments

logan_ellis2d ago

Ultrasound is the real answer.

logan_ellis1d ago

Yeah, because every home mechanic has an ultrasound machine in their garage next to the duct tape. Real helpful. I'm just gonna start whispering sweet nothings to my carbon steerer and hope it tells me its secrets. The dental mirror trick is about as high tech as my budget gets.

bell.felix1d ago

Look, I get where @logan_ellis is coming from, but dismissing ultrasound just because it's not in your garage misses the point. The dental mirror is a good start for surface checks, but it won't find internal damage. For carbon, that's the real worry. Telling people to use the right tool isn't about shaming budgets, it's about safety. Sometimes the right answer means taking it to a shop that has the gear.