Originally Posted by
thirdgen
Really though, how would you fix it? Frame builder?
Originally Posted by
3alarmer
...yes, that's a sign of a front end crash, and there are not a whole lot of other possibilities. The fork does not always bend on those, so probably not a replacement that someone went to the trouble of color match painting. I have a similar bike, and I like the way it rides...they were a very fine production bike out of the glory days in Japanese bike exporting to the United States (the Maruishi's also show up in Australia, for some reason.) I have realigned frames that were similarly damaged a few times to make them ride more closely to the original design. It's not especially difficult, but you can end up making the problem worse if you have no experience with cold bending bike forks and frames.
IN essence, the procedure is to remove the fork and headset, then insert some dummy steel headset races in the upper and lower ends of the headtube. (this is to prevent ovalizing the head tube.) It's easier to do if the frame is stripped of all wheels and components as well. Then you slip the head tube over a piece of steel plumbing pipe that is just small enough in diameter to fit through those dummy races, upside down. The pipe is held in a sturdy bench vise, and you need clearance at the bench so that you can exert some downward force.
Clamp a scrap rear hub or rear axle into the rear dropouts(it ought to be disposable, because the axle can bend, but usually does not.) Then take a long 2x4 ( your lever) and run it up under the edge of the workbench, and over the dummy axle/hub in the rear. This gives you a relatively controllable lever for exerting bending force in the opposite direction from what happened in the crash. You'll never get it exactly perfect, but you can get it aligned almost to the point where the head tube angle duplicates the original, and most of that bulge underneath disappears. It does take quite a bit of force, but be careful not to go too far.
Or if you're happy as is, enjoy riding it.
...here is a bicycle I repaired with the same sort of frame head tube damage using the method described above. It rides fine, although the original geometry was a little bit idiosyncratic to begin with, having both a short top tube and a relatively slack head tube angle. If yours rides OK in your experience, I woiuldn't go to the trouble of stripping the frame and cold bending it. What you have now is a bike with a steeper head tube angle than the original, and a slightly shorter wheelbase, so it probably turns and rides a little "quicker". A lot of later frames than that one were intentionally made with quicker steering.
Anyway, here's at least one example of a repair of that sort of damage by cold bending. It has not been repainted, even though you can see some cracking where the tubing was bulged.
Yes, it will probably eventually fail somewhere at the point where the tubing walls got bent and then straightened. Such failures in steel tubing frames rarely occur without warning with some prior crack that eventually propagates in a line around the tubing. I only salvaged this one because it is a Frejus, and I don't race it or otherwise ride it hard. It's just a nice older bike that I wanted to preserve in some fashion, but a true repair with new frame tubes would cost way more investment in time and money than it is worth to me as a bike. There are many other bikes that have not been crashed.
