LarrySellerz

Sup guys, my bike died on the way to work. Found the issue and installed some zip ties, and I intend on trying to get it welded back together. I don’t intend on removing any components, and know I’ll need to strip the paint back. Anyone have advice? Angle grinder? Wire brush?

dont intend on doing any heat treatment of the metal afterwords. May add some epoxy. This is my fastest commuter, and newest bike. I would be very upset if I have to trash it. The cable tie array seems to help a lot.

Please help me save my bike

icemilkcoffee 

That is a clean break and the zip ties aren't doing a darn thing. I would say the frame is toast.

Bill Kapaun

So, you expect someone to weld the DS with the crank in place. Good luck with that. I expect most weldors wouldn't want to touch that thin wall tubing with some awkward to reach portions.

The bike broke with the heat treatment intact. You expect it to hold up after you anneal/soften the joint?

I'm with the frame is toast crowd.

delbiker1 

IMO, there is no saving that bike. Save yourself and trash it.

Chuck M 

If the zip ties are working for you, just get bigger zip ties.

Shadco 

Add more zip ties and maybe some of this metal strapping, be sure to use flat washers under the screw heads.

shelbyfv

Fashion a splint from a beer can, slather with epoxy then pop in a couple of rivets.

easyupbug 

Obviously after stop drilling the ends of the crack.

Iride01 

That's aluminum, isn't it? Not going to do any welding on it that isn't going to cost you more than the bike itself unless you have a friend that will do it for free. And that welder ise going to have to be one that is really good with the skills, knowledge and have the right type of equipment to make that particular weld on that thin tubing if you want it to last very long.

If you have to salvage it and make it work for a while, you might be better off taking off most of the stuff that'll be in your way and wrapping it with fiberglass cloth and epoxy resin. It'll be ugly, but who really cares.

JohnDThompson 

How do you expect any of these fixes to hold up, without duct tape?

LarrySellerz

Luckily, my partner at work is a master welder. Ive read that the seat tube is the least critical of the tubes in the bike, but now that its gone what tube/joint is experiencing the most stress? Thats my biggest concern honestly, the bike flexes and eats up my power now but its not terrible, dont think it will crash like this.

Edit: buddy is saying take it to the shop and try to get a warranty from the manufacturer?

Koyote

You guys -- talking to Larry as if he'll ever follow sound advice. You crack me up.

HillRider

Best advice you have gotten.

delbiker1 

I was thinking this very thing when I posted. This post made me chuckle.

LarrySellerz

If I keep riding it as is, what’s the likely failure mode?

Andrew R Stewart 

Now much more stress is being placed on the rest of the joins, which one will fail next is less the question than what will happen when that next one fails. I would like to see the face of the break but I suspect it started at the weld's edge as undercutting is a well known stress riser.

I would ask Larry what about this bike makes it worth trying to fix. Sentimental value? I fully understand trying to do a repair to see if one can. But as others have pointed out the repair is one that often isn't a long term fix, has challenges to do well (even with all removed and access is not the problem) and does nothing for the remaining frame joins/tubes that have seen the added stresses that the crack's faces displacement shows has happened.

"You guys -- talking to Larry as if he'll ever follow sound advice. You crack me up." koyote
If some of us seem to be sounding like that I will apologize somewhat and defend that attitude with our having considered this type of question here so many times before, and watched those OPs seeming to want to only listen to the replies that agree with their initial belief. I don't think the discussion here has, as yet, descended down that path too much. Andy

icemilkcoffee 

That is not true at all. That seat tube / BB junction is the most frequently cracked area on steel frames. The headtube just above the lower lug is another location that frequently cracks. Followed by the down tube right across the brazed-on cable stop mounts.
This is the reason why Serotta and Ritchey started using seat tubes that flare out at the bottom where it meets the BB.

Eric F 

Best Choice: Warranty replacement (if that's actually an option)
Good Choice: New frame
Risky Choice: Repair attempt. Any repair of the broken tube will be less structurally sound than the frame was originally, and the potential for a catastrophic disaster increases significantly.

LarrySellerz

Frame is Scott and no longer under warranty. He thinks he can weld it back together, said it failed in the 'heat effected zone" at the base of the weld .He has me looking up heat treatment and said we can do it with a thermocouple and an oxyacetylene torch, but I am skeptical, I think doing a terrible job of heat treatment might be worse than no heat treatment.

The frame was complaining on the way to work, creaking sounds, its not looking good. The zip tie array isn't doing much anymore it flexes on every pedal stroke

JohnDThompson 

The down tube/bottom bracket joint is the next likely failure point. Unlike steel, aluminum does not have a fatigue limit, and every flex brings it closer to failure. The increased flex resulting from the seat tube failure will accelerate this process.

Manufacturer warranties only apply to the original owner, and you need to have documentation to show that you are the original owner (e.g. bike shop receipt showing new bike sale to you). Writing as a former warranty claim inspector for Trek in Waterloo.

squirtdad

all that creaking is aluminum fatiguing in preparation for failure, each pedal stroke is on closer to failure in the other joints and other places.

as best i understand (talked to my brother who has lots of welding experience) Oxy-Acety can weld aluminum, but it is very dicey with thin wall tubing.....more likely to burn through the tubes. Lot different than say 1/4 in plate

Frame is toast, just accept that and move on, don't put your self at risk or others trying to fix it

maddog34

some other weld-stressed joint will break, followed by your face hitting the pavement.

and whoever told you that one of the most common break points on a bike frame isn't critical should not be listened to.

it failed due to poor heat treating/ANNEALING, bad engineering, and the side-to-side loading of pedaling.

engineer at a factory...."It was fine until you rode it! I think YOU caused the break!"

i advise that you find a different, better, brand of bike frame and swap your parts onto it... or quit pedaling.

LarrySellerz

thanks! I ended up going this route. I didn’t know how to take off the cranks/chainring and it got kind of epoxied as well, but I wiped it pretty well and I guess I’ll see what happens tomorrow. Honestly I’m kind of disappointed in the quality of this repair, really should have taken the chainring off instead of working around it. Live and learn I guess.







I was able to drill and tap a 1/4-20 hole into the blue version of this epoxy previously so it’s pretty strong

Iride01 

I hope you were able to get several layers of cloth in there. Cloth is what adds a lot of strength for tension and torsional loads, IIRC.

And you need to make sure that cloth is fully saturated with resin. Not just laying on top or bottom of the cloth.

It'll be interesting to see how long it does or don't last before you get a crack again.

squirtdad

very little chance of this working or making much more difference than the cable ties.
wiped it of pretty well,. means it most likely will not adhere, which is critical
no compression of glass and resin means very little structural strength
just glomping on a ton of epoxy does not make it strong

frame is dead