Hey there, new to this page but was curious if anyone has had carbon repair done on their bike with success? I recently purchased a used but new to me 2024 trek speed concept SLR 9, just picked it up from my local trek shop had them go through it give it a tune up and clean. Brought it home had it in the garage and planned to take it downstairs to put in the training room. My kids were in the garage and they accidentally ran a plastic remote control car into it and it fell over on the concrete. I was pretty upset but only noticed some chipping/scratching on the basebar and thought that was it. The next day I noticed the entire downtube is cracked and I can’t believe it’s even possible from such a light fall. I’m devastated as I’ve only rode it twice and spent an arm and a leg for this bike. I’ve spoke to my trek shop and they said they will contact trek to see what they can do but I’ve done some research and found some carbon repair shops that specialize in road bikes but don’t know if it would ruin the feel of the bike or if the carbon would be laid correctly and be strong enough. Never mind would be impossible to resell the bike at a later time with a third party carbon repair. Not sure what to do other than go even further broke replacing the frame. Anyone have experience with this type of situation?
thanks

I did a repair on my carbon fiber Kestrel road bike last year…

Link: Carbon Fiber Frame Repair

My advise is you have little to lose doing it yourself if you go slow, understand the materials, understand the process and have some basic skills…

The repair will need to use specific unidirectional CF fabric and epoxy…

There are probably a bunch of YouTube videos showing how to do it…

Getting the right materials matters…

In the USA I recommended https://fiberglasssupply.com/

I guess I would be asking Trek how a bike falling over onto flat concrete - where the down tube can't actually hit the ground anywhere - would crack the primary structural member of the frame. That shouldn't be possible. Do you know for sure that it was intact before?

That said, our bike shop has had many excellent repairs performed by Ruckus in Oregon. Both full paint restorations and very smooth basic spray-overs. Also had some experience with Calfee - who also do a great job. No one has ever reported a change in ride quality, nor would I expect any. The way they repair the carbon doesn't involve tons of extra material, and all of it is fiber oriented to match the original.

There is almost a night and day difference between a 1987 Kestrel and a high end carbon bike today in terms of the carbon structure and wall thicknesses.

Ruckus Composites, https://ruckuscomp.com It will be as good as new (if not better).

I had the chainstay on my Madone SLR8 repaired by a specialist (in the UK) after the derailleur cage smashed into it going over a pothole. Bizarre accident that punched a decent sized hole in it. They repainted it too of course. Expensive but you would never know it had been done.

Maybe previous damage.

Thanks for all the input. My local trek shop is going to submit a claim with hopes of warranty but sounds like the best they can do for crash warranty is 20% off. I don’t think there was any previous damage as I had the bike looked over by two different bike shops since I bought and I’ve spoke to the previous owner and he has told me it was never dropped or crashed But who knows. I’ve got a few responses from carbon repair shops for quotes one for 800$ and one for 1000$ Canadian dollars as I’m in Saskatchewan. Now I guess I need to decide if I want to save money now with the repair and potentially lose money when I resell down the road or spend the money now on a new frame and still hold a decent resale value.

Trek plays hardball with warranty only applies to original purchaser. The companies that have the best experience and results are a consideration, but the cost is not cheap.

Whether it’s “worth it” to repair is a tough call and should be balanced against replacement cost.

I hope that helps.

Yeah those prices sound about right. Mine was over £500 including paint (which was almost half of it)

Shouldn’t affect resale value - I mean the repair will be totally safe and look like new if done by someone reputable and I wouldn’t feel the need to disclose it personally.

if it will be better than new, then why doesn't Ruckus get into the frame manufacturing business? Seems like they would easily take a big piece of the pie, if even their repairs make a frame better than new.


^ similar to the joke about how the whole plane should be made out of the Black box, since that survives crashes.

These things can be fixed. Try Cyclocarbon or Appleman bicycles. Depending on where you are, there might be more local options

https://www.cyclocarbon.com/
https://www.applemanbicycles.com/repair/

Designing something and repairing something are not comparable. A good auto mechanic doesn't know how to cast an engine block.


The resale value of bikes are low. I wouldn't spend a ton of extra money over repair costs - you won't recoup it.


I'm still scratching my head trying to understand how a downtube can break when it can't possibly touch the floor. Seat, bar, fork, pedal, rear derailleur, wheels all keep the frame from touching a flat surface.

Was mostly just joking- hence my inclusion of the old black box joke.

Seriously though, making it better than new seems doubtful. Or 'better' may be have a different definition than the brand...carbon layup patterns and whatnot.

Really? What if they used a higher quality carbon fiber and epoxy and then a better compression/cure recipe? The affected area would be stronger and lighter than original?

Then that goes back to my initial comment that was joking- they should design and manufacture full frames if they have better build processes.

This is getting dull. Maybe you should think about things before posting. To answer the question, because repairing a small section is different from manufacturing a frame. For a repair, labor costs overwhelm material costs so there is minimal impact from using higher quality materials. Also, since their volume is so much smaller than a major manufacturer, the costs associated with a longer process can also be easily absorbed.

Stronger than the adjacent frame members = stress raiser at the junction of the old and new material.

Which is exactly why Mil-Specs were developed on how to prepare the frame and do the layup to avoid it and why Ruckus follows them.

That isn't the way it works, or every butted tube in the world would have stress riser failures at the butts. The stress risers that earn that title have to be pretty sharp and severe.

To recap- concern about stress risers is accounted for thru the repair process, but stress risers are also not a concern and not accounted for because they don’t need to be, and proof of that is butted carbon tubes don't get stress risers.

Glad that's cleared up.**

Am I the only one having Shawshank flashbacks?

I had a broken seatstay repaired on a Cervelo frame about 15 years ago. I was always afraid to ride it outside afterwards (going 40+ mph downhills) so I stuck it on my indoor trainer. I have been riding that bike indoors for the last 15 years with no problems. I think I made the right decision though. My safety and piece of mind was more important than the money I spent on a new outdoor bike.

I guess it depends if you believe the repair process is actually different than how carbon frames are made in the first place.

15 years on a trainer is probably a lot more stress than actual road riding, since the rear hub is locked in one plane all the time.

I see that is one expensive bike. I would hesitate to buy something like that used myself as you could be buying someone else's lemon but paying a high price for it. I would consider having it repaired but also consider finding a compatible frame for the components and riding style.

When I crashed my still new CF bike back in 2005, I found a replacement frame that had been ridden about the same amount of time from the same company, but a different model and just swapped over all the parts. I still ride it. I've upgraded it over the years with better wheels, crank/BB, and replaced chain and cassette many times. I've rebuilt the Campy shifters. It still rides silently like it was new. I also still have the crashed frame and you can barely tell it was crashed, but the fork was completely toast. I've thought about resurrecting the frame for indoor trainer use but in the end it would cost too much to even make that work because I stripped off all the parts.

But I still wonder how a small fall like that could crack the downtube. Carbon is supposed to be strong, not fragile. After all, they build airplanes out of it.