Carbon frame repair

shedhead

Hi all,

Happy new year to one & all !

Toying with the idea of changing my carbon frame (which is a works hp zerofour) & have seen a cube lightening on ebay which says it has been professionally repaired on the seat stay.

should i avoid or does anyone have experience of reapired frames / horror stories ?

thanks

ride_whenever

Personally I'd avoid like the plague, if they've broken it then it HAS been abused so you simply cannot trust the rest of the bike.

That said, i'd get my own carbon frame repaired as I know the history.

ricky1980

you only has this guy's word for it. personally if you really want a bargain, ask for details of the repair.

ask for receipts and who carried out the works; then ask why was the bike taken to the shop for repair and how the accident or break happened. and ask about the extent of the damage...if it is a full crack or some micro-crack

then ask the same questions to the shop and see if the stories match up. and ask the shop if they x-rayed the frame and found any other anomalies. ask if the crack has penetrated all the carbon layers or how many etc etc...if it is just the superficial top one then it should be fine as the structural layers are below that top one.

seat-stay is part of the suspension system of the bike for the rear wheel they can be made thin to provide "cushioning". the seat stay doesn't necessarily experience the most extreme forces as part of the frame but they have very high cyclic stress, as the carbon shape is generally smaller, i suspend they are more vulnerable to fatigue than the top/down/seat tubes. so a cracked section there will probably not be ideal...

to be very honest...just avoid the frame 100% as this seat stay will be the weakest point of the frame and it will likely to crack again. the unfortunate thing about carbon is that they tend to fail catastrophically i.e. they have no indication that they have failed before a crack appears and your frame is gone. unlike carbon, ti/steel bike can work perfectly happy if it is dented, but if a crack appears, you can still see the propagation of the crack over time and then eventually the bike will fail. Alu bike can work fine with dents too, but if there is a crack it will also likely to suffer catastrophic failure if not dealt with...but the fact that it can be deformed is good, it means unlike carbon you just don't know if the frame has suffered damages until too late.

passout

Unless very cheap I'd avoid.

cougie

I'd have thought the repair could be the strongest part of the frame now ?

Definitely a good idea to find out who did the repair and ask their opinion. I doubt I'd bother unless it was very cheap or my dream bike.

ricky1980

cougie wrote:

I'd have thought the repair could be the strongest part of the frame now ?

i can't imagine there is a glue out there can compare equally to the natural longitudinal strength of the carbon fibres...so whatever they glued it with is going to be weaker than the fibre otherwise we can just coat a shed load of this glue on hair and forget about carbon fibre. unless it is some kind clever chemical reaction to force the fibre to join up again but that can't be right as monocoques are set in resin and baked at high temp and pressure to get all the fibre to sort of attach to each other.

i may be wrong for the above...

cougie

I guess it depends on how its been repaired. Whack some extra CF round it and it should be stronger ? A bit like a broken bone - that usually gets thicker and shouldn't break again - least not in the same place ?

rolf_f

There's occasionally folk on here who work in the carbon fibre business and they seem happy enough that carbon frames can be repaired effectively and strongly.

However, how much money really is it worth to save to take the damaged repaired frame? If a mint frame was £500, how much cheaper would the damaged frame have to be? Presumably the cosmetics haven't been repaired so it won't look so nice. You'd have to talk to whoever repaired the frame because without that the repair could have been done by anyone. For me, if someone offered the £500 frame for £100 I'd still probably think I'd rather spend more and get something nicer - particularly if I had to go and built the thing up.

ricky1980

Ditto

MattC59

Depends on who did the repair and how it was done. This guy does fantastic work, I've been to his workshop and seen it first hand. He also did a small cosmetic repair to my wheels, which I can't fault.

http://www.carboncyclerepairs.co.uk/index.html

Not sure I'd buy a repaired frame, but I'd definitely use him if I needed a frame repairing.