Every cloud ...

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
Don Whybrow wrote:
snip
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.

Rob Morley wrote on 18/11/2006 18:23 +0100:
In article
Don Whybrow wrote:
snip
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.


http://www.dutchbikes.nl/bodies_uk/frame_ks2.htm ?

--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci

In article
Tony Raven wrote:
Rob Morley wrote on 18/11/2006 18:23 +0100:
In article
Don Whybrow wrote:
snip
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.


http://www.dutchbikes.nl/bodies_uk/frame_ks2.htm ?


Something like that, but I do my own welding. :-)

Rob Morley wrote:
In article
Don Whybrow wrote:
snip

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
Don Whybrow wrote:
Rob Morley wrote:
In article
Don Whybrow wrote:
snip

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.

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.

On Sun, 19 Nov 2006 13:10:01 +0000, Rob Morley wrote:

In article
Don Whybrow wrote:
Rob Morley wrote:
In article
Don Whybrow 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.


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.

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