southerndownhill.com - Forum

ok, so i found a crack in the paint under the headtube of my dh bike, so i took the paint off with wet and dry paper and couldnt see anything, so touched up the paint and kept on riding, but kept an eye on it, got back from riding today and noticed the crack has re-appeared  :( its just the thinest of hairlines in the paint, but is it possible i filled in the surface of the crack when i got the wet and dry paper on there? or is it just the paint settling, etc? hasnt been painted long, a month or so and been ridden less, maybe 6 rides, any help appreciated,

Matt.

same happened to a frame george and i had in france, when we wet and dried it we filled the crack, after a few runs you could see the crack again, sounds like it could be game over  :(

i feared as much  :( is it worth welding?

Matt.

What frame is it?

its a yeti dh9, so it is getting on a bit, but im a student and cant afford a new frame  :(

Matt.

Word to the in future wise.

Use nitromorse to remove paint when looking for possible cracks
as abrading (sanding) the area often will not reveal the true
situation.

Yeah get it welded and keep an eye on it.

Visit ( NOT phone ) any local industrial fabricators or engineers listed in yellow pages as
alloy welders.

Visit at lunchtime, ask for the office and the works manager.
Be very polite, and explain your a poor student ( if your an engineering student you'll get more sympathy ) owing £1000s and your bike badly needs a tiny weld.
Explain you'd be happy to pay standard rates but just can't afford it.
Ask if you can get one of his welders to do it in his lunch hour for beer money £10-£20.

If you work at it. You will find someone willing to help.

Good luck m8

ive had the chain stay welded, so ill take it back to the same place, but i was just wondering can you re-weld a headtube? cos on the chain stay, they welded in a plate, but on the headtube do you just run another seam of weld along?

matt.

Hi

I have a bighit frame that has just been powder coated like a few hours of riding ago. Im just getting into dh so not a rider doing huge drops etc. And ive got the same problem, hair line cracks in paint below the headtube. Havent stripped the paint off yet, was just wondering if you have found out wether it is a crack or not ?

cheers

Nah youd wrap a brace around the tube to support it. Perhaps fill the crack. But the brace will provide some support for it. I Know of someone who could do this.

havent taken any paint off yet, its going to a welders tomorrow, but im fairly sure it is cracked  >:( and i think ive seen your post of your big hit on here and that does not look good either...

Matt.

mmm, i spose i might as well get it looked at... i know someone local who will do it on the cheap, cheers though  :)

Matt.

Hey dude
You say that its going to the welders tomorrow and I see you live in glouscester too (well thats what it says on your profile)
Let me know what they say (plz) coz mine is cracked and id like to see if it can be welded up too and dont know where to take it!
cheers

yea, hopefully, if i can sneak out of work  ;) ill be taking to a place inbetween stonehouse and stroud if you know the area?

Matt.

Hang-on - you have a crack, larger on the inside than you can probably see on the outside, in the downtube/headtube weld which is the most highly stressed part of your frame and the one that keeps your face and the ground separated by your forks and front wheel.

Welding alloy and not re-heat treating in the most highly stressed location on a DH frame is not good.

Just ok in shock mounts/stays etc to get a few more minutes/hours/weeks of life from your frame but welding a headtube crack is bonkers and you risk spreading your face over the ground the next time you come up an inch short on a double or drop a bit front heavy.   Bad times.

Join the credit crisis, buy a new one and ride safe.

i see your point, but its ally, so its not gonna just go without warning, it will crack again first, if it does then ill have to think again  :(

Matt.

youve said it now  :-\

It won't if it cracks in the same place as you'll have dramatically changed the grain structure in that area of the frame.  I am resisting un heat treated aluminium is as brittle as glass speach again. 

Its your call, and it might be fine, I'm trying to give you the benefit of my experience and erring on the side of safety.  Its your headtube FFS, no part of the frame is more important to you or your health and any weakness there is not a good thing.