sweatforfun

My roommate got doored. Her steerer tube is seriously bent. The bottom of the headtube is stretched to the point that the cup can be removed and replaced by hand. once "installed" it can be jiggled slightly. it is 1" threaded. I've already told her that i believe the frame should be replaced altogether. I thought i should ask and give the frame a chance at a second life.

Panthers007

Nope. The amount of structural damage would mean getting a skilled frame-builder to, basically, replace the front-end of the frame. This would cost as much as a replacement. I hope the car-driver has good insurance.

CCrew

I'm with Panthers007. Not worth the risk unless done right, and then it's surely cost-prohibitive. Strip it for parts and put the good on a new frame or buy a new bike.

FBinNY 

The bellmouth you describe has gotten fairly common over the last decade or so. The problem is that when builders started tig welding frames, many forgot to replace the band that used to be part of headlugs. The resulting un-reinforced thinwall headtube isn't strong enough to properly support the pressed in headset cups.

If, and this is a big if after a crash, there is no other damage the frame may be saved. First check the underside of the downtube for the characteristic buckling that head-on impacts would have caused. If there is none, I doubt that the crsh alone caused the bellmouth. It probably developed over time and the crash finished the process, or brought it to your attention.

A quick fairly cheap repair can be made by using body filler on the inside of the tube and re-reaming it. Note this will solve the immediate problem, but will not stop the bellmouth process. A better job can be done by building up the inside with braze, but if you're doing that go the extra mile and add a reinforcing ring to the outside.

It's up to you as to whether this is worth it, but if it's a nice frame otherwise with no other issues, I'd t least have a decent builder or frame repairer quote for the brazed ring. If you need a few references PM me and I'll give you names of folks who can do this nicely.