I have an aluminum P3 with a structural crack on the seat stay. I’d like to try and repair it, and found a product called lab metal - basically an adhesive made for aluminum repairs. Has anyone had experience with it?
Thanks,
Brian
I’m no engineer but this sounds like a really bad idea. A seat stay seems like a part of the frame which carries a big load on a small tube. I would think that if your repair failed at a high speed you would need to repair more than your bike. I would check with the manufacturer about repair or replacement.
Yeah, check with Cervelo first, and if they don’t want to hook you up for cheap, find someone with a high-end tig welder that has experience with aluminum. Would probably be best to heat-treat it again after welding, but that may not be an option.
Chris
I’m the second owner of the frame, so no warranty or free replacement is possible. I’m looking for a cheap option (re-welding the thing will be more expensive than getting a new one). I’ve ridden with someone who broke their seat stay clear through going downhill once - nothing but a little waggle in the steering. But maybe I’m not being cautious enough.
Thanks,
Brian
If it was mine it would be new bike time. I’ll take risks on the bike but preferably not of the frame collapsing under me kind…
You could not pay me enough to use lab metal for what you are talking about. It is great for filling surface voids and such, but it is not going to do anything to repair a structural crack.
Think bondo with aluminum filings in it and you have a good idea what lab metal is. There is no way it will repair a crack.
Either weld, get a new frame, or start wearing a LOT of extra padding, but don’t waste your time with lab metal.
-Andy
There is an option to “fix” the frame that no one has mentioned, unfortunately, it only works if the crack is in the middle of a frame member, and requires a fair amount of fabrication skill.
It is possible to machine a compression sleeve that perfectly matches the contour of the cracked tube, such that it supports the damaged tube. Visualize an aluminum clamshell, with an interior contour matched to the frame tube, that is long enough to cover the entire crack plus some more, and is capable of being fastened in such a way that it prevents any further movement of the area of the frame where the crack is.
This solution is ugly as hell, but it works, and is less expensive than a new frame, if the frame is valuable. I “invented” this solution many years ago, at a frame shop I once worked at, and it was applied successfully on more than one occasion. A notable “fix” was an Ellsworth Truth that had a top tube cracked entirely through. After the gizmo was installed, the frame was perfectly rideable, and was used for at least another full season in it’e repaired state.
Good luck!
I have a friend that would be able to fix it for you. With an aluminum frame you wouldn’t be able to heat treat it again as the frame would most likely twist. If you want to PM me I can give you some more information. He’s located in Canada so you would have to ship the frame up.
I had a similar experience w/ my mtb during a race. The chainstay snapped completely but I was able to finish the race…just had some wobbles in the corners.
Sounds like a good idea, how did you fasten the extra piece of aluminum to the tube?
Thanks,
Brian
I will add another to the “don’t do it” column.
It just isn’t hardly a good idea to even try and repair an aluminium frame, save for Fredly’s solution; however, it would just be easier to return it for a warranty replacement. I am certain you could be hooked up for a similar or better replacement.
While a seat tube failing is probably not going to cause a crash in all but the weirdest cases, it is still be a royal pain in the arse. Just replace the frame.
Actually, you should be able to find any local machine shop that has a tig welder can repair this. They’ll have to grind the paint off of the area to weld it, and it shouldn’t need to be heat treated. Its a road bike, not the space shuttle landing gear. If you’re charged over $100 to weld it, you’re being ripped off.
If you bring in the frame with all the components stripped off, and they’re not busy, they should be able to weld it in 10-15 minutes.
I know a carbon framebuilder who overwraps carbon onto ally frames with midtube cracks. It’s just a composite version of fredlys solution. You may be able to find a local place that deals with carbon that could do it for you.
Doubt it will work. The real problem is that the stuff will probably not penetrate far enough into the crack and get close enough to the tip to actually reduce the crack propagation rate. Infiltration methods work in theory, by reducing the deltaK for crack growth but in reality they are ineffective due to lack of penetration.
How deep is the crack. If it is very shallow it may be possible just to grind it off.
The crack is to deep to just grind out, but you do bring up a good point about the adhesive penetrating the crack. I was thinking of filing the crack down - opening it up in a sense - before putting the lab metal in. Do you think this will be enough, or will I still have trouble penetrating enough for the lab metal to do its work?
Thanks,
Brian
Opening the crack will help you get it in there, but…it will not stop crack growth, only slow it down. Also once the stuff gets in there, it will cure. The crack will grow and the resin will not flow to the tip. The further the penetrant is from the crack tip, the worse it does at slowing growth.
Bottom line, once you have a crack, if you apply stress it will propagate. Therefore the only long term fix is to remove the crack, by grinding or weld repair. The other option is to reduce the stress sufficiently to get deltaK below threshold for crack growth. The sleeve as some have pointed out will work by carrying part of the load, thus reducing the effective stress (and deltaK) at the crack tip.
Good luck.
Thanks for your help.
-Brian