Cracked Frame?

I have had a strange creaking noise from the front of my bike. I tried tightening/loosening the headset, but made no difference.
The creaking occurs when you move the forks back and forth. (as would happen when you apply the front brake while travelling in a straight line).

So I stripped it and found these marks on the downtube / headtube weld.
Possibly a crack. Not sure.
But after putting it back together the creaking has dissapeared, so it could have been the headset?
The bottom headset cup is a very loose fit, so it might have something to do with that. But these marks are like a crack. Any ideas?
The frame was resprayed (at home) recently.
I have sanded down the area in the pictures that look like a crack but can't see anything on the metal?
It's a 1991 Klein Rascal which has been doing downhills at Hagg Farm and Wharncliffe Woods recently
Chris





The pictures make it look less like a crack than in real life.

.

If you sanded it down and see nothing, it was most likely a headset issue, if one of the cups was coming loose, this could definitely cause creaking.

As for the cracks, if you used a cheap paint, and did a poor job on the spray over, then it's highly likely you'll have chipping/cracking and such on the paint.

Odd creaking noises can even originate from the stem/bars interface and yet sound for all the world like a frame problem.

If the headset cups are loose in the frame refit them using some Loctite 641. This will deal with any potential movement but will still allow future disassembly.

Look like stretch marks to me - the old girl isn't getting any younger

my guess is the frame is about to fail and what you see there is where the paint has cracked .you wont see the crack in the frame because all thats going on is the alloy is stretching past the elastic point of the paint.this frame wont crack it will fail like carbon fibre jobs or ten year old kleins and snap completely..this because the bending in the alloy makes it harden until it wont bend then it willgo big time.dont ride the frame it might remove your teeth at the worst moment.imho.

I know what you mean about stem and bars creaking. I had a bike that was terrible for it.
I jammed the rear wheel against a wall and moved the forks back and forth, and it still made the noise. So the bars and stem (and brakes) have been eliminated.

As for the quality of the paint and the quality of my respraying, yes it's possible. I left it for 2 days after spraying before I spent at least a couple of days after spraying it rubbing it down polishing it etc. The paint surface was very smooth. So I don't think (although it's possible) that it's that.

South Bound - were you joking or did you mean something along the lines of the post below yours?

gibbleking - are you saying that it will stretch a certain amount and then suddenly snap?

The cracks in the paint run from the downtube into the weld of the teadtube, which seems a bit strange. As surely the tube/weld would stretch/crack at different rates?

Thanks for your awnsers!

Do you have graese before the assembly of the headset ?

24pouces":3kqvk1p5 said:

Do you have graese before the assembly of the headset ?

Click to expand...

If you mean on the bearings then yes.
It looks like the lower cup was also greased before fitting. Although it's a very loose fit. When I removed the forks the lower cup came out with it.

I'm begginging to think that the creaking noise was the headset, as now it's been refitted it's not creaking.
It's more the crack/stratch marks I'm worried about.

Chris

If the lower cup is so loose that it came out with the steerer tube then you need to be checking for ovalisation and slight "belling"of the headtube.

You can do this with a pair of vernier calipers or bore gauges and a micrometer. If you don't have the kit then take the frame to an engineering works and ask them nicely if they'll check it for you.

Don't ride it as it is, as you'll only make it worse.

It might be worth trying to find a headset that has a longer portion where it presses into the frame. Some DH headsets are like this to better spread the load.
If you can be certain that the frame is otherwise sound (this is the hard part,deciding whether you can trust it...) then when you refit the headset use bearing Loctite, otherwise the bottom race will just keep fretting and hammering away at the headtube and bollox it completely :roll: .

The lower cup is looser than my seat post! It's been like it (AFAIK) since I bought it (second hand) 13 years ago. It was definately like it 10 years ago.
Looking inside the headtube, it looks like a headset that was slightly too big has been hammered in at some time. You can noticably feel a ridge around 7mm into the headtube, this goes all the way around.
I had assumed this was something that was done at the factory, but looking at the top of the headtube it's not like this. So I guess someones done it at some point.

As for trusting it, thats the problem. It's 17 years old so I guess it's done well!
I've been out looking at bikes today, so her time might be up!