Damaged my brand new TCR Advanced frame by chain suck

I feel your pain. I purchased a Liv Avail Advance 2 in August as soon as the 2020 bikes were launched. I've had nothing but trouble with the paint work. The same as you, my chain jumped off on my second ride on an incline and took a chunk of paint off. Since then I've seen other chips in my paint work. I've been so disappointed. I see comments here about taking the bike back - I did, they weren't interested!  I was advised to use nail varnish by the Giant Store I purchased it from and then to add helicopter tape. I was shown other carbon bikes in the store with paintwork chips and been told to expect it from paint work on carbon bikes as the paint isn't a robust due to the paint being different (powder). So disappointing. 

What is it with all this ‘seal it with nail varnish’? Why?

That is pure and simple chain suck, caused by the chain being dropped off the inside of the little ring and then dragged up the back of the inner ring against the frame.

You can just leave it, or if you want it aesthetically correct, get it repaired properly in terms of repainting. I cannot see for the life of me why you would want to take some wet and dry to it and then use nail varnish! What do people think they are achieving by doing this? 

If you know how to repair paint then fine, go ahead and do it. I’ve done plenty of repairing of paintwork on cars over the years and if you take wet and dry paper to it, you need to be doing it correctly otherwise you are just making a mess.

You take various grades of wet and dry, lower grades first to flatvthe area. This will mean you remove quite a lot of the paint all around the damaged area. You then use finer and finer grades to feather the paint edges. For a scratch that deep you will end up with an area about four times the size of the damaged area to feather the paint sufficiently.

You may need to build up the scratch with a bit of filler/ filler primer and then flat it again to get a smooth finish. Once you have done this you can then move onto respraying the area to match. This will require colour matching the paints, a spray gun or airbrush and accurate masking to achieve a descent renewal of the paintwork. After the paint has hardened it will require a lacquer coat to seal it and cutting/ polishing to achieve the correct finish.

What exactly will nail varnish achieve, especially if applied using a nail varnish brush? A gloopy mess. Why?

If you want it fixed properly and can’t do that yourself, pay someone with the required skills to do it for you, or just live with it. Bearing in mind it is behind the chainset it can hardly be seen as it is. A proper repair would not be that expensive.

PP

Bit of sanding with wet and dry and steal some clear nail varnish from the better half will sort the cosmetics as it doesn't look structural. 

Pop some of this over any areas where you could get stone chips, cable rub and around the chainstay; https://www.amazon.co.uk/d/DIY-Home-Improvement-Tools/Protection-8671HS-...

If you want to do it on the cheap, as you have a black bike use an old inner tube with a thin black/clear zip tie round it and as other people have mentioned by a chain catcher!

Trickier to do with carbon frames than metal ones, but my bikes, where possible, have several thin zip ties around the chainstay to avoid exactly this.

Pretty sure I've seen self-adhesive stainless patches for this, too.

Just to add, I did have a chainstay fail on a trek 5000 (carbon frame) and it was quite bizarre really - I tried to pull away at the lights and the back wheel wouldn't turn round.

When I got off the bike, the wheel spinned - took me a good while to work out what was going on! As soon as load was applied to the chain the wheel pulled forward and wedged against the other stay.

So yeah, exceedingly unlikely you'll come to any harm should the frame fail in this area.

Funnily enough this story sounds very familiar.

My TCR Advanced had chain suck when it was just a month or two old, took a lump of paint off the chain stay and I was very upset with it, but mostly myself as the rings were a little bit dirty which could have contributed (and I think I had also changed the cassette from 12-30 to 11-28 without shortening the chain, although that shouldn't really matter).

Anyhow, put a bit of white insulating tape over the damaged areas (as luck would have it the paint was white....) and I'm still riding the bike now perhaps 5 years (and about five thousand miles) later without any issue, and I've killed a few other frames in the intervening period.

So yeah, I suspect the frame is completely fine, but in view of how new the bike is it might be worth reporting the damage to the bike shop and perhaps trying to get something in writing to confirm that this won't effect the warranty/guarantee as there is no question of poor setup/maintenance (by yourself) being responsible at this early stage - you don't want it to fail in a year or two and for them to try and blame you for letting the chain suck happen due to poor maintenance/whatever.

As above there are also numerous carbon repair shops that can fix the frame should it come to it.

Best of luck!

Below is the chain stay of my Canyon Ultimate after a chain drop while Zwifting earlier this year. The edge of the metal plate that was double-sided-sticky-taped on to protect the frame got caught by the chain and was ripped off, causing damage to the paint (which looks like the case in the original pic  in this thread), and at least one layer of carbon fibre. Not sure if it was the top of the chain being pulled downwards, or the bottom pulled up by chain suck. I sent it off to the fantastic Rob Hayles at https://carbon-concepts.co.uk/ who did a great job at repairing and re-painting it so it now looks at least as good as new.

Just lacquer it. Got similar damage in a few places on mine after stuff like my father in law using my propped up bike as a sawhorse. In some ways there's a nice release in having a damaged bike, a bit like if you've got a car with a few scrapes and you no longer care if someone scratches it.

Presumably, new bike, new chain?

Been a little while since I opened a new chain but I sort of recall that they are shipped with a grease which might be a little sticky, especially in the cold. I usually give them a good wipe down and a few squirts of ACF 50.

I don't care what anyone else says - I'd be taking it back to the shop for replacement or refund. For that to happen on a second ride is unacceptable and the fault of whoever set the bike up

As folk have previously posted, that’s just superficial damage and it doesn’t need to be looked at for structural integrity problems. You have a few aesthetic repair options - buy some wet and dry sandpaper from Halfords and sand the area down so there are no more flakes of paint, then get some clear nail varnish and give it a few coats to seal it in. You could also just buy a matte black chainstay protector, cut a section of it and stick it over the offending area after sanding off the flakes (don’t pick at the flakes).

You should always use a chain catcher

Looking at the width (top to bottom) that looks too long to be a chain but there are two/three strips  down that look about chain link width apart. Almost looks like the damage has been done upwards not downwards. No chance it was your shoe/heel from a missed clip in or something else more random?

Also agree with others that it doesnt look like any damage to the carbon. You get chips that deep from inside the chainstay where wheels might rub or under the bridge of the seatstay from stuck stones but as you are not sure how the damage was done best ask the shop at the very least.

yeah, I am not convinced that is chain suck, probably more a case of either the setup not being right or just bad luck (hitting a bump in the road mid-shift). 

As above, get the damage checked out (there are quite a few good CF repairers out there now) although it does look cosmetic.  Might also be worth getting a chain catcher fitted as part of the front shifter check/setup afterwards (the Token ones work well and cost as little as a tenner).

I think that's just paint damage, personally. If the CF is damaged, you normally see loose threads sicking out. But it's better to be safe than sorry, and a scan of the frame might put fears at rest.

I'd get it expertly checked.
2nd ride and a shipped chain.
Might want to ask the bike shop, I'm presuming it was from a bike shop, to check the set up and see why the chain was able to come off the chain wheel.
Looks like the indexing/ front derrailleur may be out a tad.

Chain suck is something I have experienced several times over many years and it was usually associated with a mountain bike triple drive train.  I think it is more likely when a chain is worn and doesn't drop off the bottom of the chain ring and gets carried up and "crunch". One recommended way of treating damage to a carbon surface is put super glue on it. After that I would put a few layers of reinforced tape on the chain stay to protect it against the next time it happens.

Wow that's a bit of a knightmare, that's a hell of a crunch. You should check your chain and try and find out why you experienced chain suck. I don't think that I can remember ever experiencing it.

I reckon there'll be no structural damage done there, it's a very tough part of the frame, best you can do is put some clear coat over it.