Cracked BB

Svendo

Guru
Location
Walsden
Unhappily I was just regreasing my BB to try and cure it's creakiness and found the real cause which is an inch long crack on one side. :ohmy:
Put it back together as I guess it's usable for the moment, but I imagine it's an uneceonomic repair (focus alloy frame) so frame is essentially doomed. :angry::sad:

Am I right?
 

g00se

Veteran
Location
Norwich
How old is the bike and are you the first owner? If it's not too old - or from one of the companies that have lifetime frame warranties - you should be able to get it repaired/replaced for free.
 
OP
Svendo

Svendo

Guru
Location
Walsden
It's just over warranty (3years) and it's been crashed last september and repaired at the rear dropout, which probably would have prevented warranty replacement anyway.

I suspect the crack has been slowly growing over the last 9 months since I crashed it, and my recent removals and refitting of the BB have brought it on.

Just looked again now and with the BB refitted it's opened up a bit, so I'm not sure it's even safe to use at all now :sad::sad:
 

Globalti

Legendary Member
But anyway, why not get on the phone and find a welder who can do aluminium, then get the threads recut. What have you got to lose? If nothing else you can flog it as a repaired frame for a few quid while in its current state it's useless.

I was selling a Ti frame once but didn't feel I could sell it with nasty chainsuck gouges in the RH chainstay. So I found someone who said he could weld Ti and heart in mouth, left it with him thinking it would either be a beautiful job or the end of the frame. Collected it next day and was amazed at the job he'd done; he had blobbed titanium under inert gas into the gouges and refinished the tube to the point where the repair was almost invisible. I sold the frame with a full explanation of what I had done.
 

battered

Über Member
My friend had an ally frame with chainsuck gouges to the point where the frame had holes in. I took it to an ally welder we used at work and for £10 it was sorted in a tea break. It's back in use as a spare bike while he decides whether to restore it properly with tasty bits or just continue to use it as a hack with parts from the bits box.
 
OP
Svendo

Svendo

Guru
Location
Walsden
Sounds like it'd be worth taking the frame round to some welders once I've stripped it to build the new bike. Thanks for the suggestions. Any advice on finding one? yellow pages I'd guess?
 

Globalti

Legendary Member
Blimey, I've just noticed you're in Rochdale! The firm I found was Pennine Welding Ltd in Littleborough, Tel: 01706 374 903, they are on the left just off the A58 Halifax Road as you approach the junction for the Todmorden road.

Ask for Mr Harris, he's the one with the glazed look in his eyes and the beads around his neck, a true craftsman. You'll understand why I was apprehensive! He did the job during his lunch hour for £20 IIRC.
 
OP
Svendo

Svendo

Guru
Location
Walsden
That's brilliant Globalti, thanks. Nowt like a personal recommendation. Funny to think how many hundreds of times I've cycled past there on the bike in question!
 
OP
Svendo

Svendo

Guru
Location
Walsden
Thanks for the advice Catrike. What do you mean by ground out, is that cutting out the crack or something else?
 

Globalti

Legendary Member
I thin Catrike means that it would be better to remove material from each side of the crack and fill the gap with new metal by welding, then refinish the outside and re-cut the threads inside. I can see how this would be stronger than just blobbing weld on the outside, which would look unsightly and would leave the original crack mostly unrepaired so that it could continue to spread.
 

g00se

Veteran
Location
Norwich
Yeah, with any 'sharp' cut into metal, there are points of stress at the tip (that's why aeroplane windows have rounded corners). This can lead to failure and further cracking. In some situations, to stop a crack spreading, it's common to drill a hole through the tip of the crack so there is no further leading point for it to spread.

By cutting out the crack and 're-filling', there's less chance of such a fault remaining.
 
OP
Svendo

Svendo

Guru
Location
Walsden
Ah yes, that makes sense. Thanks again for the advice. This might determine if it's repairable or not as the crack very nearly meets where the chainstay is welded onto the bottom bracket. I'd be suprised if it'd be worth the cost of removing the chainstay and rewelding it on again. Once new bike arrives and I've stripped broken one down I'll get in touch with the welder and we'll find out.
 
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