Frame Repair

[twentysix by twentyfive]

My pal has an Aluminium frame which has some cracking around the seat tube where the external clamp forces the frame tube to clamp the seat post. The cracks (each side of the slot which permits some flex) are apparent on the inside of the tube as well as the outside and the metal does flex. Has anyone any experience or knowledge that might suggest that these cracks can be repaired? It's only a matter of time until the cracks lengthen and the whole lot is a disaster. Can these be Al welded and the tube machined (inside and out) so that the seat post and clamp will fit properly again? If so likely cost? Or linky to a webby site please.

TIA

Oh - I really am asking for a friend

 

[Ajax Bay]

Best of luck ( to your pal) on a repair attempt. Can't immediately envisage the forces that would result in these cracks propagating (further).
Caused by trying to tighten (with some persistence) on a smaller diameter seat post than needed, perhaps.

 

[Illaveago]

Do you know what aluminium the frame is made from ?
I have a Carrera Vulcan which was scrapped . It had saw cuts in it and had a couple of splits in the head tube . I welded the split and saw cut up using a mig welder . I have ridden the bike for a while but one of the splits in the head tube has opened up again and another split has now appeared . The saw cut has held .I will try to weld it again but it may be that the aluminium has aged and will continue to split .

 

[Cycleops]

Best and safest advice would be to buy a new/used frame.
The repairs you outlined would be approaching the cost of a used frame anyway.

 

[twentysix by twentyfive]

Thanks everyone. My pal has decided to buy a new (or second hand) bike.

What I didn't mention was that his steerer tube had broken too (carbon) and his handlebars were only held in place by the bolt to the star fangled washer. Lucky him or it may have been a trip to A&E.........

 

[wafter]

Crikey!

Best decision IMO; once it's started to go you've got to invest a lot into welding it, which will probably only cause it to go again with the residual stresses it creates.

Proper steel bike now, then...?

 

[Venod]

What I didn't mention was that his steerer tube had broken too (carbon) and his handlebars were only held in place by the bolt to the star fangled washer.

A star fangled washer in a carbon steerer is bad practice, this could have led to the failure.

 

[Jameshow]

If it was a 32.6mm seat tube I found that if you cut it off a 27.2 fitted in perfectly!

So you could bond a 31.6 in place and then cut the top off use a 27.2 clamp and clamp it up.

If anyone has this issue again in 2030!!