Carbon Frame & Impact Damage
Discussion
Hi everyone,
Managed to do this to my Cube Elite SHPC at the weekend (3rd ride out on it!), an innocuous section of paving slab flicked up and impacted the underside of the down tube. The damage appears to be confined to the thick clearcoat / paint with some minor carbon strand damage, there is no abnormal flex to the area and no obvious cracks through the wall. I rode it for another 25km after the damage happened with no adverse effects.
Bike shop 1 said - they'd not worry to much about it from a structural point of view, they'd do a light sand of the damage then apply epoxy over the top to re-seal/protect - £20.
BIke shop 2 said - again not too worried structurally but due to a few broken strands would add a couple of layers of matting to strengthen - £100.
I'm just looking for some second opinions (ideally from people have experience repairing these frames) on what to do in terms of repair as although I've been to a couple of bike shops I'm not convinced they have that much experience. Do I:
1. Light sand myself then apply white paint over the top
2. As bike shop 1, sand then epoxy to protect.
3. Strip frame and send to a professional carbon repair specialist
I'm not bothered about aesthetics but just want it structurally sound.
Managed to do this to my Cube Elite SHPC at the weekend (3rd ride out on it!), an innocuous section of paving slab flicked up and impacted the underside of the down tube. The damage appears to be confined to the thick clearcoat / paint with some minor carbon strand damage, there is no abnormal flex to the area and no obvious cracks through the wall. I rode it for another 25km after the damage happened with no adverse effects.
Bike shop 1 said - they'd not worry to much about it from a structural point of view, they'd do a light sand of the damage then apply epoxy over the top to re-seal/protect - £20.
BIke shop 2 said - again not too worried structurally but due to a few broken strands would add a couple of layers of matting to strengthen - £100.
I'm just looking for some second opinions (ideally from people have experience repairing these frames) on what to do in terms of repair as although I've been to a couple of bike shops I'm not convinced they have that much experience. Do I:
1. Light sand myself then apply white paint over the top
2. As bike shop 1, sand then epoxy to protect.
3. Strip frame and send to a professional carbon repair specialist
I'm not bothered about aesthetics but just want it structurally sound.
I know of a 'dale Supersix that got repaired here, very good job too.
http://www.carbonbiketechnics.co.uk/
http://www.carbonbiketechnics.co.uk/
http://www.fibre-lyte.co.uk/fl/fl_frame_repairs.ht...
I know these guys do a lot of repairs...never had anything repaired by them but I have seen their repairs and they look good.
They make parts from Carbon Fibre too, chain rings etc so seem well versed in its use http://www.fibre-lyte.co.uk/fl/bicycle/bicycleintr...
I know these guys do a lot of repairs...never had anything repaired by them but I have seen their repairs and they look good.
They make parts from Carbon Fibre too, chain rings etc so seem well versed in its use http://www.fibre-lyte.co.uk/fl/bicycle/bicycleintr...
I suppose the crux of my question is does it need actually repairing? Or can I just stick some clearcoat protection over the top and carry on as usual?
I'll get it repaired if need be but I'd rather not stick a load of carbon matting on the top of a structurally sound tube.
It's not the cost of the repair that puts me off but more the hassle of stripping the bike, posting it off and being out of action for 2/3 weeks.
I'll get it repaired if need be but I'd rather not stick a load of carbon matting on the top of a structurally sound tube.
It's not the cost of the repair that puts me off but more the hassle of stripping the bike, posting it off and being out of action for 2/3 weeks.
Why risk it for the sake of under £100 (what that place I posted charge) - without tarring all bike shops with the same brush, I would not trust half of them to fit a bottom bracket let alone judge by eye if its acceptable to ride a broken carbon frame...
I get the hassle part, but certainly less hassle than it giving up on you at 30mph down a hill...
I get the hassle part, but certainly less hassle than it giving up on you at 30mph down a hill...
okgo said:
Why risk it for the sake of under £100 (what that place I posted charge) - without tarring all bike shops with the same brush, I would not trust half of them to fit a bottom bracket let alone judge by eye if its acceptable to ride a broken carbon frame...
I get the hassle part, but certainly less hassle than it giving up on you at 30mph down a hill...
Even less hassle is just buy a new frame which I trust 100% ... I get the hassle part, but certainly less hassle than it giving up on you at 30mph down a hill...
This is why i'm asking for second opinions, i'm not convinced it's actually broken. No cracks through wall / no flex / no springy material just top coat/paint damage (I think, i'm no expert). I rode it for 25km afterwards with no change. I don't mind stripping the bike, paying £100 and being without it for three weeks to repair a broken frame .... I'd rather not for a structurally sound frame with a bit of paint damage.
I suppose I'm never going to know for sure, my options are either replace, repair and cross fingers or continue to ride and cross fingers.
Re. local bike shops, agreed ... and that's why I'm reluctant to use a local place as I think they're just saying yeah stick some material on top and charge £100.
John Laverick said:
I suppose the crux of my question is does it need actually repairing? Or can I just stick some clearcoat protection over the top and carry on as usual?
I'll get it repaired if need be but I'd rather not stick a load of carbon matting on the top of a structurally sound tube.
It's not the cost of the repair that puts me off but more the hassle of stripping the bike, posting it off and being out of action for 2/3 weeks.
Your first line is the question none of us can answer, CF can fail with no visible indication, the most common effect of impact damage is delamination of the opposite side to impact ie the bit you can't see on the inside of the tube. I'll get it repaired if need be but I'd rather not stick a load of carbon matting on the top of a structurally sound tube.
It's not the cost of the repair that puts me off but more the hassle of stripping the bike, posting it off and being out of action for 2/3 weeks.
If it's not flexing it's not a guarantee that the section is ok, it may still be intact enough to not flex but one or two layers may be comprised.
A simple tap test can indicate structural soundness but I'd still want to get it x-rayed ideally to understand the full picture.
Layering up mat and resin won't help if the inside face is damaged.
That area of the down tube will be subject to all sorts of loads, it wouldn't be pretty if it failed.
That's not going to catastrophically fail, it may continue to crack and eventually fail, I'd just seal it and continue riding it. I watched someone trying to finish off a carbon frame with a big crack (more like chunk missing) mid down tube from a big impact, he was brave and kept hitting a 6' gap jump purposely landing short, it took a lot to separate the head tube completely.
Matt_N said:
Your first line is the question none of us can answer, CF can fail with no visible indication, the most common effect of impact damage is delamination of the opposite side to impact ie the bit you can't see on the inside of the tube.
If it's not flexing it's not a guarantee that the section is ok, it may still be intact enough to not flex but one or two layers may be comprised.
A simple tap test can indicate structural soundness but I'd still want to get it x-rayed ideally to understand the full picture.
Layering up mat and resin won't help if the inside face is damaged.
That area of the down tube will be subject to all sorts of loads, it wouldn't be pretty if it failed.
Agree with Matt, but beware, an X -ray may not give you the full picture either. See if you can borrow a borescope to visually inspect the inside. When CF fails it can be very quickly and very spectacularly. Food for thought here: http://www.bustedcarbon.comIf it's not flexing it's not a guarantee that the section is ok, it may still be intact enough to not flex but one or two layers may be comprised.
A simple tap test can indicate structural soundness but I'd still want to get it x-rayed ideally to understand the full picture.
Layering up mat and resin won't help if the inside face is damaged.
That area of the down tube will be subject to all sorts of loads, it wouldn't be pretty if it failed.
eta - this is a useful website: http://www.netcomposites.com/guide-tools/guide/rep...
Edited by Moaningroadie on Tuesday 5th January 23:03
carbon test - https://www.youtube.com/watch?v=xreZdUBqpJs
I would just ride it, whats the worst that could happen?
People worry too much.
I would just ride it, whats the worst that could happen?
People worry too much.
X rays and boroscopes, really? You actually think the frame is worth that kind of expense?
Lot of hype and FUD about carbon as ever. Yes, it's probably got concealed damage - the 'lifted' fibres suggest to me that there's been substantial deformation and the've snapped. It probably won't fail, most of the load path will be intact, and the tube is massively stronger than it needs to be. I'd also be a little surprised if it went suddenly rather than degrading gradually, but I'd not chance it. A well done repair with a few layers of carbon over the top will be more than adequate so long as it is properly keyed in, has enough overlap etc, and shouldn't cost the earth.
Lot of hype and FUD about carbon as ever. Yes, it's probably got concealed damage - the 'lifted' fibres suggest to me that there's been substantial deformation and the've snapped. It probably won't fail, most of the load path will be intact, and the tube is massively stronger than it needs to be. I'd also be a little surprised if it went suddenly rather than degrading gradually, but I'd not chance it. A well done repair with a few layers of carbon over the top will be more than adequate so long as it is properly keyed in, has enough overlap etc, and shouldn't cost the earth.
gp1699 said:
carbon test - https://www.youtube.com/watch?v=xreZdUBqpJs
I would just ride it, whats the worst that could happen?
People worry too much.
The frame snaps, and goes through a part of your body. Resulting in a very long time under the knife to remove all the carbon shards.I would just ride it, whats the worst that could happen?
People worry too much.
I've seen the results of a carbon arrow doing just that, and the resulting mess is not nice.
Gassing Station | Pedal Powered | Top of Page | What's New | My Stuff