A colleague at work had an accident a few weeks ago where he was waiting at a T junction to turn right onto the main road and a car turned right off the main road but did not make any allowances for other vehicles. He got away with a minor scrape on his arm, but the bike took enough of a ding to the front that it has bent the frame, forks and front wheel. He had a LBS do and estimate for repair including a new frame and the driver has coughed up the full amount. The colleague has decided to lay up from cycling over the winter and sold me the bike for a nominal sum. Now you may be excused from wondering what I am going to do with a bent bike, but it just so happens to be the same model as my bike [1] and I now have an almost full set of spare bits including recently new or renovated Nexus8 workings, BB & rear roller brake (front is suspect, I will need to inspect). It is possible I can salvage something from the front wheel as well, but I will need to strip it down to see.
My parts bin overfloweth!
[1] Ridgeback Nemesis
-- Don Whybrow
Sequi Bonum Non Time
At first there was nothing. Then God said 'Let there be light!' Then there was still nothing. But you could see it.
In article <[email hidden]> Don Whybrow <[email hidden]> wrote: <snip>
Quoted message said:
Now you may be excused from wondering what I am going to do with a bent bike
I'd be inclined to straighten it and ride it. Depends quite how bent it is though - it might have to be converted into a recum-bent.
My colleague said that the LBS had told him that the frame was out by 4mm, although he did not divulge to me the location or direction of this bend. My best guess is that the head tube is at a slight angle going top left to bottom right. The forks have a definite bias in this direction. With the frame being Aluminium, I am not sure if this can be corrected without causing any fatigue. I would imagine that this would have an interesting effect on the steering if not corrected. I suppose it would be worth getting a frame builder to take a look, but I don't know of any around here (Edinburgh) and I am not looking at spending any significant sums at getting it straight.
-- Don Whybrow
Sequi Bonum Non Time
If you find yourself in a hole, the first thing to do is stop diggin'.
In article <[email hidden]> Don Whybrow <[email hidden]> wrote: <snip>
Quoted message said:
Now you may be excused from wondering what I am going to do with a bent bike
I'd be inclined to straighten it and ride it. Depends quite how bent it is though - it might have to be converted into a recum-bent.
My colleague said that the LBS had told him that the frame was out by 4mm, although he did not divulge to me the location or direction of this bend. My best guess is that the head tube is at a slight angle going top left to bottom right. The forks have a definite bias in this direction. With the frame being Aluminium, I am not sure if this can be corrected without causing any fatigue.
Fatigue is caused by cyclic stress, not a few tweaks with a big iron bar. The problem is propagation of cracks caused by work hardening, which then act as stress raisers. I imagine one solution for this is heat treatment to anneal the frame before setting then de-stress it after setting, but I'm no expert on aluminium alloys.
Quoted message said:
I would imagine that this would have an interesting effect on the steering if not corrected. I suppose it would be worth getting a frame builder to take a look, but I don't know of any around here (Edinburgh) and I am not looking at spending any significant sums at getting it straight.
Depending on the distortion you could have a go at straightening it yourself with a big iron bar and a couple of helpers, then check it with a dye-penetrant crack testing kit once you'd got it straight. But it's probably not worth the hassle.
In article <[email hidden]> Don Whybrow <[email hidden]> wrote: <snip>
My colleague said that the LBS had told him that the frame was out by 4mm, although he did not divulge to me the location or direction of this bend. My best guess is that the head tube is at a slight angle going top left to bottom right. The forks have a definite bias in this direction. With the frame being Aluminium, I am not sure if this can be corrected without causing any fatigue.
Fatigue is caused by cyclic stress, not a few tweaks with a big iron bar. The problem is propagation of cracks caused by work hardening, which then act as stress raisers. I imagine one solution for this is heat treatment to anneal the frame before setting then de-stress it after setting, but I'm no expert on aluminium alloys.
Trying to anneal the frame is a bad idea. Much depends on the initial heat treatment. Some heat treatments require computer controlled ovens, not something you can do at home.
Fatigue also depends on the heat treatment.
Quoted message said:
Quoted message said:
I would imagine that this would have an interesting effect on the steering if not corrected. I suppose it would be worth getting a frame builder to take a look, but I don't know of any around here (Edinburgh) and I am not looking at spending any significant sums at getting it straight.
Depending on the distortion you could have a go at straightening it yourself with a big iron bar and a couple of helpers, then check it with a dye-penetrant crack testing kit once you'd got it straight.
Dye penetrant can only be carried out on bare metal, so paint would have to be removed.
Quoted message said:
But it's probably not worth the hassle.
Probably not.
-- Mike
Van Tuyl titanium Dura Ace 10 Fausto Coppi aluminium Ultegra 10 Raleigh Record Sprint mongrel
