I posted this on the triathlon sub and it was suggested to post here for better advice.

I am looking at purchasing a used Giant Defy Allux bike for a beginner tri I’ll be doing next month. It seems in great condition except for this small dent in the top tube. I have no idea if this is/could be a significant problem or it is nothing so hoping for some help.

For context the bike leg is 15km and I’m riding no more than 30-50km week on a bitumen cycle track while training so it’s not getting a lot of use.

by MolassesSerious1403

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11 Comments

  1. Personally I wouldn’t but a damaged carbon bike as you have no idea what it’s been through. Sure it might be fine, but, you don’t want to find out if it’s not.

  2. Yeah, not a big deal. Need to dent in a good fraction of the tube size to really worry about compromising it. It’s the kind of thing where you’d worry without an ultrasound on carbon, but no biggie on alloy.

  3. Kind-Entry-7446 on

    its only an issue if the aluminum is compromised. thats a paint chip. nothing to be worried about unless it starts growing. then you might have the bike powder coated for more than you paid for it. look for bends,dents or cracks in the alu tubing.

    you may want to increment the bike training a bit more, ideally one race shouldn’t be equivalent to half your weekly training or you may burn out hard mid race. i suggest riding the rout at least a couple times to shake down the new bike.

  4. It looks like a paint chip. But looks can be deceiving. Tap among the top tube with something metal – a spoon, a hex key – and listen to the sound. If the note changes, it may indicate damage to the carbon fibre that you should get inspected by a professional, immediately.

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