I’m sure plenty of people on here have cracked their carbon frames and felt their stomach lurch as they realise that warranty isn’t going to cover it. Well, I’ve just had my frame repaired and I was so impressed that I felt I should give the chap who fixed it for me some publicity.

First of all, here’s my cracked frame:

Cracked frame 1 by sbarley, on Flickr

Cracked frame 2 by sbarley, on Flickr

Cracked frame 3 by sbarley, on Flickr

As you can tell, the seatstay is almost snapped in half. I think at some point my rear mech must have pinged round, hit the frame and left a crack that got bigger over time. At this point you could see sunlight through the crack! I didn’t think repairing carbon frames was possible, but On One wouldn’t accept a warranty, so I decided to ask around and give give it a shot.

One of my mates pointed me in the direction of Steve, an engineer working in Plymouth who had repaired his carbon fibre road bike frame. I called him up, and dropped the frame off with him later that week. He updated me by email with detailed descriptions of his process in repairing the frame, along with photos:

Repairing the frame 1 by sbarley, on Flickr

Repairing the frame 2 by sbarley, on Flickr

Repairing the frame 3 by sbarley, on Flickr

Repairing the frame 4 by sbarley, on Flickr

Repairing the frame 5 by sbarley, on Flickr

So, after all that, here is the finished frame! I can’t believe how neat the job was. According to Steve, in a lot of cases carbon IS repairable and is then in fact stronger in the area that has been repaired!

Finished frame 1 by sbarley, on Flickr

Finished frame 2 by sbarley, on Flickr

Finished frame 3 by sbarley, on Flickr

So if you’re not sure what to do with that ‘broken’ carbon frame you have, go get it fixed. The prices are very very reasonable and the service is second to none.

Email Steve at compositeframerepairs (at) hotmail (dot) co (dot) uk

How did it break there?

Read his words

Oh aye.

Missed that bit when the pics were loading.

That looks like a very tidy surgical scar for a bike.

<goes off to ebay to look for broken carbon frames>

Very tidy job, how much did the repair cost?

Rear mech must of?

I think you would know if the rear mech hit there because you would have lost the hanger, mech and most likely twisted the chain.

Very neat repair though. Credit where credit is due.

This guy does a similar thing too, I’ve seen one of the fixed frames – looks like new. Theres a (slight) weight penalty but not much.
http://www.carboncyclerepairs.co.uk/index.html

My friend got a quote to fix a steel frame that had been gouged/corroded at the chainstay and it was more than the frame cost new.

*starts business*

*starts business*

are you sure people will fork out for spoons?

*buys spoons*
🙂
edit(Damn your speed Waswas Grrr)

are you sure people will fork out for spoons?

I’m not sure if this is the right tine to be starting that sort of business.

That’s tidy. Could you pop his descriptions of the job up too?

He’s back:

CaptainFlashheart

I’m not sure if this is the right tine to be starting that sort of business.

How was solitary?

I had my old boat repaired a few times and they guys that did it also did all the carbon warranty repairs for a major bike manufacturer. They reckoned fixing a bike was easy where as a carbon mast for a boat was harder as you had to replicate the bend characteristics so was more involved.

muppetWrangler – Member

That looks like a very tidy surgical scar for a bike.

<goes off to ebay to look for broken carbon frames>

lots and lots of people already do that – broken carbon frames go for £80+, you can buy a carbon repairt kit for less than £30 and repair most breaks yourself at home relativly easily.

monkeyboyjc – Member
you can buy a carbon repairt kit for less than £30 and repair most breaks yourself at home relativly easily.

I wouldn’t be trusting myself with that tbh.

This thread sums up why I would never buy a carbon frame – they just never looked strong enough to me.

Carbon is a high tech. product at the leading edge of engineering development. It is appropriate for those with sponsorship for competitive riding, where value and durability are not really a concern.

IMHO, having a carbon frame for recreational use is not justified, completely OTT and attracts people who just enjoy showing off.

Yeah cause steel, ti or aluminium NEVER break.

If al can do it anyone can

The problem I have with the repair is that it looks good. But how many layers of carbon has he used? Are they going the right way? The look is the least important part of the repair.

they just never looked strong enough to me.

trololol. internet engineer alert!

The prices are very very reasonable

One man’s reasonable is another man’s “HOW MUCH!?!?!?”

So what’d it cost?

I had (still have really) a crack at the BB area of my trek elite, started to get a bit worse so decided rather than bin the frame to give a repair a go.

Bought kit from carbonmods for about £30, sanded the area down, epoxied, wrapped carbon, epoxied, wrapped carbon la la la…

3 layers to be sure, couple of strap areas as the BB is kinda awkward and an overnight dry. quick smooth off with some paper and a lick of spray can and I was back riding it the day after.

It’s not the prettiest, I’ll probably mix up a bit of carbon powder and epoxy at some point to fill and smooth, but it’s still in one piece.

£30 and a bit of time, that or bin a frame and buy a new one…

and 40 quid on adequate mask and gloves ;O)

This thread sums up why I would never buy a carbon frame – they just never looked strong enough to me.

Carbon is a high tech. product at the leading edge of engineering development. It is appropriate for those with sponsorship for competitive riding, where value and durability are not really a concern.

IMHO, having a carbon frame for recreational use is not justified, completely OTT and attracts people who just enjoy showing off.

Santa Cruz Nomad Carbon Vs Aluminium Test video.

Personally I’ll take a lighter, stronger carbon frame over an aluminium one any day. I’d also doubt an aluminium V10 frame would have survived the final ‘test’ in that video un-dented…

been repairing these things for a while

problem is now with ultralight some things are scrap once you bust them patching them just moves a failure further up Once had a discussion with a carbon repair whizz where i was completely wrong abut the layup despite the fact i actually had it and the ply book had my name on it in the rev 1 box

best to keep quiet now

some things are scrap once you bust them patching them just moves a failure further up

This is why I’ve not had my road frame repaired – unless the repairer is able to check the complete frame for potential cracks, how do I know repairing the visible one will make it ok?
(This frame was hit by a car btw and the cracks were not visible until after a few rides)

This is why I’ve not had my road frame repaired – unless the repairer is able to check the complete frame for potential cracks, how do I know repairing the visible one will make it ok?
(This frame was hit by a car btw and the cracks were not visible until after a few rides)

Im not saying you cant repair a lot of them ,the gear is available to do NDT ,touted it to 3 big manufacturers as warranty backup or qualification for failures ,TBH none of them could give a shit if they are getting their warranty frames from the factories for free and even when they pay for them its a big question mark over if its worth it!!

To do a proper NDT on a frame and make the money back on 8K for an Ultrasound unit and 10k for the thermo unit means charging folks more than they like to pay

40 quid repairs to avoid scrapping a frame is what most folks want and thats fine if you want to make a living doing it ,there will be more folks jumping on the bandwagon without a doubt

NDT = ?

Non Destructive Testing ….sorry

But if you know some one who does NDT and has the kit but works else where they may be willing to do it for you, I had my old Dh bike tested when the rack fell of a friends car at 70mph it was fineif a little battered, test cost me nothing(but my brother does this,unfortunaty he works on oil rigs and has moved all his kit out there)

(but my brother does this,unfortunaty he works on oil rigs and has moved all his kit out there)

your brothers a smart guy he’s probably making money with his equipment
oddly the company that supplies the “special composite scanning heads” used to do lots of oil industry work till they discovered carbon aeroplane parts (and they built Boeings Advanced composites facility 10 mile from them) were ripe for “NEW training methods” followed by a slew of whys and whatnots and ooooh carbon is dangerous

pesky MTB riders spending ££££s on carbon and saying they dont have mega money like oil companies do….does my head in

This thread sums up why I would never buy a carbon frame – they just never looked strong enough to me.

Carbon is a high tech. product at the leading edge of engineering development. It is appropriate for those with sponsorship for competitive riding, where value and durability are not really a concern.

IMHO, having a carbon frame for recreational use is not justified, completely OTT and attracts people who just enjoy showing off.

People always talk about the ‘strength’ of carbon v ally or steel but it’s missing the point entirely.

CF has a much higher specific strength and modulus than either ally or steel. A bike frame (or any structure where weight is a driving factor) if designed properly for a given material’s properties, will have been analysed/sized to be as ‘strong’ as it needs to be for its intended use and lifetime. If it’s stronger than it needs to be, then it’s also heavier than it could be.

CF’s much higher fatigue strength than steel or ally means that damage notwithstanding, a carbon frame will probably outlast an equivalent steel frame and FAR outlast an ally frame.

The repair looks like a decent enough job (I’ve seen worse on flying parts!) and should be more than adequate if it’s been scarfed in properly. As compositepro says though, you can introduce new stress concentrations around the repair.

But if you know some one who does NDT and has the kit but works else where they may be willing to do it for you, I had my old Dh bike tested when the rack fell of a friends car at 70mph it was fineif a little battered, test cost me nothing(but my brother does this,unfortunaty he works on oil rigs and has moved all his kit out there)

That’s fine for checking a frame to see if it’s damaged in the first place, checking a repair is a different situation.

Pulse echo A-scan is realistically the only NDT method you’re going to be able to use on a bike frame, and that will indicate the quality of the laminate (the presence/absence of voids/delaminations) but any NDT method will NOT tell you whether or not the laminate is actually up to the job – that’s an analysis (and maybe destructive testing) exercise. Of course all this costs (a lot of) money and in virtually all cases it’s just not worth it commercially on a bike frame, or even close.

In practice, when all is said and done, with the relatively small loads and simple load paths on a bike frame, if it looks strong enough, it probably is.

Whenever I see these repairs I think of bone fracture healing. When your body repairs a broken bone is overbuilds the area which results in a stronger section. When people repair a composite part they are either going to mess up and not make it strong enough or what is more likely they will slightly overbuild the area so in a lightweight, highly optimised structure you change the way it responds to load and can cause problems around the repair. Obviously nature is better as it breaks down the excess material over time restoring the structure.

It is this change in response that makes sailing masts much more difficult, but then a mast is not only very expensive and worth repairing but the amount of waste if you discard it is much higher than 1-1.4kg of bike frame.

If the composite structure is built quite burly (eg a mountain bike) then it’s not so much of an issue and the load paths on a bike are quite simple and the wall thickness (and thus number of layers) is very low. Much simpler than the 25mm+ thick stuff I’ve been working with recently.

Right everyone, will try to answer your questions:

Footflaps & DezB — the repair cost £50 all inclusive

pjm84 — I said ‘must have’ not because I think the rear mech twanged the frame, but because I know it did but at the time the crack wasn’t huge! I.e. why I can only guess that this was the initial cause for the crack and it developed over time. Trust me, I really did know about it…snapped hanger and singlespeed ride home!

Spongebob — you would be surprised at how repairable carbon is! Steve buys broken carbon frames, repairs them and rides them himself. He has repaired road frames where the top tube was physically in two pieces. However, he broke an aluminium frame, and guess what? He had to chuck it. Non-repairable. So for me, carbon is the way to go. I’m not necessarily saying this On One frame is fantastic, but you can be sure I will never go back to a non-carbon frame, whether I have to buy it myself or not. And YES I am a racer, but I live on Dartmoor and only have one mountain bike, so this has to withstand pretty harsh terrain. I’m pretty happy that in the knowledge that if it does break again, I can get if fixed.

richmars & midlifecrashes — Steve worked out which way the fibres were running, stripped it down and rebuilt it exactly how it was but better (apparently the manufacturer’s build quality was awful under the first few layers). If you want more detail, here’s a compilation from the emails he sent:

In short the impact did more damage than was obvious. I’ve attatched the photo’s hopefully which shows the extent of it, apart from the obvious crack what didn’t show was that the opposite side of the tube delaminated internaly. When i ground away the filler (more on that later ) and started to go through the layers of carbon one area suddenly broke away leaving a hole. I’ve now put on a single thin layer of carbon to give a firm layer to work with when applying the rest of the plys.
 
Alot of the big name manafacturers use lots of ply’s of carbon sheet in various orientation’s to achieve the desired properties, when i ground the Race frame i took away the top layer of paint and then some white filler followed by a layer of biaxial carbon. This doesn’t really contribute much to the tubes stength and is mostly for show, expecting to find lots of plys of different orientations underneath it i was suprised to find a few plys of unidirectional plys running along the seatstay only. If there had been lots of different plys in one orientation  i would’ve thought nothing of it but there wasn’t much there and the stay was very thin. Where the dropout was bonded to the carbon the manafacturers had put quite alot of filler to smooth out the area, they could’ve used more carbon plys just in that area instead of filler. It wouldn’t have added much weight but could’ve added more strength to the area. I’ll put the rest of the plys on next week and take more photo’s as i go.

Right then, the laminatings all done and i’m sanding the excess resin off on monday morning. I’ll then spray the black paint to blend in the back end again and laquer the repair along the seatstay. The green you see in the pictures doesn’t stay on but is a disposable cloth called peel ply, this protects the surface from contamination and provides a keyed surface for subsequent layers.

andyl — You are quite right: the frame will probably be stronger than it was, so in terms of forces, the frame might not behave quite like it used to in terms of stiffness and flexibility. I am no expert about this though, so if you want to know more try emailing Steve directly.

Nice 🙂

Anyone know how/who to use for carbon respray?

Good to know carbon can be fixed if it breaks as I’ve just bought a C456

Avoid all this by getting a metal bike!