Repairing aluminum

[bluedog225]

UPS took a bite out the bike I recently purchased used.

Components are worn and I’m doing a frame up rebuild.

I don’t think it’s structurally significant. But I’d like to repair it. Either cosmetically or structurally. Without doing any damage to the remaining metal.

What do you guys think? Something like bondo and repaint or can metal be flowed in without compromising the existing structure? Or something like a clamshell repair. I’m open to any ideas.

Or best just to lightly sand, repaint that little area, and move on. Photos below. The last is a stock photo. The electric motor stuff you see is being removed. It will have a Pinion drive on the front and just a chain tensioner on the rear.

Thanks

 

[Recoveryman]

It looks deep in a critical part of the structure. Have you considered welding (filling)? What do you want to do?
Recoveryman

 

[bluedog225]

It looks deep in a critical part of the structure. Have you considered welding (filling)? What do you want to do?
Recoveryman

That’s what I’m hoping for input on. I don’t know what is possible with welding/filling.

 

[jayemm]

Maybe fill it using those "aluminum welding" low temperature brazing rods that melt using a propane torch. May be available locally at HD or ACE. There's more than one brand of these type rods..

Aluminum repair kits, repair aluminum by welding with a Propane Torch - Alumiweld

 

[PCustoms]

1. Contact frame builder for advice
2. File claim with UPS

 

[InsanePyro]

Take it to a welding shop, they can fill it in

1. Contact frame builder for advice
2. File claim with UPS

Frame builder is gonna tell him its junk to cover their asses and making a claim like that with UPS is like screaming at the ocean to move

 

[BillK]

Find a good welding shop and have it TIG welded. That looks like a pretty significant divot. Hard to believe that happened in shipping ?

 

[whateg01]

Maybe fill it using those "aluminum welding" low temperature brazing rods that melt using a propane torch. May be available locally at HD or ACE. There's more than one brand of these type rods..

Aluminum repair kits, repair aluminum by welding with a Propane Torch - Alumiweld

I sure don't see one of those restoring the strength lost with the material that appears to be missing. Or is it just dented? Bike frames are not usually very thick.

 

[Codyboy]

It looks deep in a critical part of the structure. Have you considered welding (filling)? What do you want to do?
Recoveryman

Unless he takes it off some sweet jumps how critical is it really?
Blue paint .

 

[theoldwizard1]

Components are worn and I’m doing a frame up rebuild.

I don’t think it’s structurally significant. But I’d like to repair it. Either cosmetically or structurally. Without doing any damage to the remaining metal.

If it is not structural and you are doing a frame up rebuild, bondo and paint.

 

[jayemm]

I sure don't see one of those restoring the strength lost with the material that appears to be missing. Or is it just dented? Bike frames are not usually very thick.

Good point if that section is tubular but it may be solid cast.

 

[bluedog225]

The frame is hinged under the seat. The rear part pivots and has a shock. Strictly touring. But gravel roads.

I don’t know if it’s tube or solid at that point. I was assuming solid. I’ll ask my Azub guy.

The replacement frame piece is about $700 delivered. The guys says it‘s trouble to install. But I don’t know the details. Though well packed by a bike shop, UPS forked the box. And tore it open on one end. They did cover the cost of the new piece. Not the install. And it has to come from Europe.

 

[mrvm]

If the replacement cost has been covered I’d use it. IMO there’s enough material past the divot and supporting structure left to handle road load…….SEND IT

 

[matt_i]

I'd run it until it breaks, if that's ever.

Going to have to strip paint all around, some is going to get burned by the radiant heat. Likely never get it coated back the same.

It's in the thicker cross section above where it's already joined to the flat stock. That top tube of the triangle is mostly in compression.

 

[bluedog225]

I looked into frame builders around here that deal with alu. And talked to the Texas dealer. He thinks it’s good to go. Even given his financial incentive to sell a new part. And the tig welding introduces a bunch of complications.

I’m going bondo and spray paint. Haven’t done that since 1980.

Thanks all.

 

[whateg01]

Good point if that section is tubular but it may be solid cast.

Looks like it's right where the drop out begins so yeah it might be heavier there

 

[rsanter]

Structural, Assuming it’s aluminum, TIG welding

cosmetic, epoxy

 

[MOwens]

I would tig weld that back in myself. But I am also a machinist/welder with some certs. Any decent welding shop should be able to fix that right up.

 

[bluedog225]

My light research indicated that the bike frame alloy surrounding the weld would need to be heat treated to restore its strength. Which is a hole can of worms. Any idea if that’s true?

 

[JSGAuto]

My light research indicated that the bike frame alloy surrounding the weld would need to be heat treated to restore its strength. Which is a hole can of worms. Any idea if that’s true?

Confirmed. If it was aged (heat treated), you will un-do that with welding.

 

[35Ford]

Epoxy filler, sand, mask and paint. Then wrap the repaired area with one wrap of red reflective tape. Put a wrap of tape on the other side to match.

 

[Firebrick43]

My light research indicated that the bike frame alloy surrounding the weld would need to be heat treated to restore its strength. Which is a hole can of worms. Any idea if that’s true?

Was the frame heat treated to begin with? I could find no mention of it and its not common with many manufactures unless they are going for minimum weight which seems to be the opposite goal of azub, to make a durable long life frame with large diameters and heavier gauge tubing.

Its actually insane to me that that tube is not worn thru and has a hole in it. That is some thick tubing.

If UPS is paying for a new one why not replace it. It looks very easy and straight forward to replace it, especially if you are removing the electric motor anyways, that is where the majority of the work with the wheel set and derailleur would be anyways. its just a pivot point and shock mount other wise.

 

[Crashlandy]

Unless he takes it off some sweet jumps how critical is it really?
Blue paint .

I bet I could throw this football over those mountains

 

[bluedog225]

Was the frame heat treated to begin with? I could find no mention of it and its not common with many manufactures unless they are going for minimum weight which seems to be the opposite goal of azub, to make a durable long life frame with large diameters and heavier gauge tubing.

Its actually insane to me that that tube is not worn thru and has a hole in it. That is some thick tubing.

If UPS is paying for a new one why not replace it. It looks very easy and straight forward to replace it, especially if you are removing the electric motor anyways, that is where the majority of the work with the wheel set and derailleur would be anyways. its just a pivot point and shock mount other wise.

Thanks. I’m checking on the heat treatment.

 

[bluedog225]

All I have is this from the website. Waiting on a response to the email.

“Built from specially developed thin-wall AL 7020 tubing, the asymmetric rear fork delivers exceptional stiffness at extremely low weight.”

 

[adsinnott1]

https://www.amazon.com/dp/B00CDDA1OW?tag=atomicindus08-20

 

[MoonRise]

UPS paid to replace the frame/piece?

Replace the frame/piece.

IMNSHO, that damage IS structural. It is big enough and in a structural area.

Not within the main diamond structure, true. But can the bike actually work without the rear axle and chainstays, nope.

7020 aluminum is weldable. But with some big conditions and caveats. It is heat treatable, and welding ruins any heat treatments. And the weld filler rod/wire used to weld 7020 is usually NOT a heat treatable alloy, so the weld bead will NEVER really be as strong as the base 7020.

The welding and resultant HAZ are not only weaker but also can corrode easier and is not as fatigue resistant.

If you do nothing to the 7020 after welding regarding heat treatment but let is sit for 90+ days at room temperature, the aluminum will "naturally age" and get back up to ~75% of the original heat treated strength.

Replace the frame/piece IMNSHO.

 

[Hohn]

Take it to a welding shop, they can fill it in


Frame builder is gonna tell him its junk to cover their asses and making a claim like that with UPS is like screaming at the ocean to move

Find a good welding shop and have it TIG welded. That looks like a pretty significant divot. Hard to believe that happened in shipping ?

I would tig weld that back in myself. But I am also a machinist/welder with some certs. Any decent welding shop should be able to fix that right up.

These guys where where I was leaning until I did a bit more research. Then I came to think @MoonRise is bang on.

The only reason to use 7020 is for a good strength to weight ratio that all but necessitates heat treat. And you simply can't just TIG that with 5356 or whatever. The location is CRITICAL on that bike and given how thin the tubing probably is, there's little to no wall thickness left. A crack is almost certain to form quite soon if you ride it a lot.

This is weldable and repairable, but it's specialty work for a dedicated bike frame specialist who has access to a a full heat treat after the repair and knowns what he's doing with 7020.

This isn't something any old guy with an AC TIG can handle. THe tube will lose over half its strength when the heat treat is lost, and aluminum without heat treat has very poor fatigue life.

Personally I'd be considering some powder filled epoxy filler or epoxy with glass fiber reinforcing. You could do worse than wrapping the area in several layers of fiberglass tape and saturating with a good epoxy resin.

 

[The Cobbler]

to me it looks like a break on the RH said . not sure what to make of the LH side ... I have mixed thoughts . I am guessing that bondo/epoxy & paint would be a sufficient fix, then keep an eye on it for future cracks

 

[egdede]

I'd wonder about non obvious damage where that Frame was 'backstopped' when the forks speared it. Be glad you were afforded a replacement piece. Use it (I know it SEEMS like a $700 hit, but it's really just you being made whole : )