I bought a new road bike from a local shop in mid April. Was going for a ride early September (so about 4.5 months old), went to put in a crank and heard a snap, pulled over and somehow the small chainring had snapped apart into 2 pieces. The broken chainring and chain fell into the BB area and gouged up the frame. Bike still had 100% OEM build on it and no work had been done on it besides cable tension adjusted by the shop. Took the bike in, and shop initially ordered a chainring from Shimano on warranty and told me the frame damage was cosmetic. I told them I'm not happy with that and want them to ask the frame manufacturer about a warranty/repair. Rep supposedly got back to shop agreeing it's cosmetic and no warranty. It's a carbon frame, Ultegra Disc 8000 series spec, so not a $15k build but not entry level either. They haven't examined the frame at a composite shop, they are basing this on pictures.
My complaint is I bought a brand new bike, an OEM part was faulty and failed causing frame damage through no fault of my own (my suspicion is the chainring bolts were either under or over torqued when they built it up), so either the frame manufacturer or shop built the bike poorly, or the Shimano part was faulty. So at best I have a cosmetically damaged frame which will be very hard to sell, because who is buying a road bike with paint damage all around the BB shell which _could_ indicate structural damage? At worst I have a compromised frame which could fail catastrophically.
If I had installed components on the bike, it was older, it was a mountain bike etc. I'd be more understanding but this is pissing me off. Also heard through a friend the exact same situation happened at another shop on a Cervello frame and they replaced under warranty.
Am I being an unreasonable dick here?