Carbon fibre – when is a scratch a gouge and how deep is too deep (C456)

Suffered appalling chain suck on my C456 last week and finally got the chance to look at it today.

The chain suck was my fault – no oil and dried grot from the last ride on the chainrings.

However a scratch an inch long 1mm wide and about 1mm deep behind the chainrings – likely to fail with 16st of idiot on board?

Helpful thoughts or mass ridicule equally welcome.

Pics?

Edit: brantbrantbrant

Bit of a git to photograph. It’s the matt black finish and the area is behind the chainrings (the crank was wanting more persuasion than I was willing to give it tonight to come out) so I couldn’t get a decent photo.

I’ll maybe try again later.

Anyone know what the wall thickness is like around there?

Mine had similar, if not worse, damage. It lasted for ages and was still fine (no cracks, creaks, delamination) when I sold it.

I’ve got a similar issue, its removed all the paint in a strip up the chainstay, it what sounds like a similar location to yours.

Its exposed the carbon fibre which looks largely undamaged so i reckon it’ll be fine, its not very pretty though with a 2×10 setup on it…

Ride it and keep an eye on it.

For all I’ve slated my C456, it was no shrinking violet, I doubt it’d even notice a 1mm scrape. Before I ordered mine, I was told that the chainstay is deliberately overbuilt to stop this being an issue. She’ll be right.

(it might not be a bad idea to cover up the damaged part though- wee bit of araldite perhaps)

What Northwind said – I cut a C456 in half to make a ‘fatframe’ – those BB chain stays are very thick CF.

Are you talking paint scratch 1mm deep or carbon? The paint is blimmin thick on these (at least it is on mine)

Thumb nail drops into hole by about 1mm – so paint plus whatever the topcoat of resin is in that area.

I’ll keep an eye on it.

i’d be amazed if it causes an issue. Most (cheap) CF frames have at
least 1mm of high build primer/filler and paint over the top layer of CF because of the “variable” quality of the cf parts direct out of the mould

(which is why you don’t generally see clear coat CF frames because it’s extremely labour intensive to make the moulds and layup to a high enough (and repeatable enough) quality in volume)

FWIW the C456 has been available in a “nude” finish, mine was like that(seemed to be a separate clearcoat rather than a top layer of resin, as loads of it fell off…)

Spoke to On-One. They agree with you folks.

The instant response was that it ought to be ok, they’d considered the chance of chainsuck when they designed it and added a load of extra material around the chainring area.

Many thanks for the replies.

Would it perhaps be worth splurging some Epoxy and chopped GF in the area and then Heli-taping over the area just in case you get any more chain sucky incidents?

My £400 road frame is clear coat. Clearly it’s not all that expensive to do.