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Cracked rear dropout

Old 08-05-22, 09:02 AM
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Lbach093
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Cracked rear dropout

Hello,
I brought my 80's (I think) Bianchi that I bought a few years ago to a bike shop for a tune up and some work, and they called me a few days later saying that they found this crack in the rear dropout. I had never noticed it, and they didnt see it when they did the first look over.
I talked to the guys at the shop and one seemed to think it was potentially mendable with some welding, and I am curious if this is actually feasible? I dont have any emotional attachment to the bike so if it would be expensive then I'll just strip the parts off, but if it is mendable and affordable then I'd like to use the frame for a project.

Some backstory: it was probably cracked when I bought it. I didnt think anything of the all black paint at the time (I assumed the paint underneath was bad) but I started to suspect that maybe there was something wrong with it and eventually this turned up. I cant be too upset, I probably got 1000km out of it for $160.

Anyways, thank you in advance.
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Old 08-05-22, 09:13 AM
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...everyone has a different idea of what's affordable. Dropouts are often repaired by welding a small gusset brace onto one side and/or brazing the crack, but I've only seen it done for higher end frames. It does ruin the paint on the stays on that side, but I guess that's not an issue for you. In your case, with your initial investment, it's hard to say whether finding someone to do the repair for 50 bucks is a sensible investment. I can't imagine finding someone who will do it much cheaper than that, and removal and replacement of the dropout would be too expensive.
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Old 08-05-22, 09:13 AM
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Steel bikes and most other bikes can always be fixed. Just depends on what it's worth to you. Frequently repairs like that will be much more than I'd be willing to pay.

I just scrapped a steel frame yesterday and don't have any remorse about it at all. Though it served me well once, I didn't have that much invested in it either. I took it to the scrap yard with 920 pounds of other steel I had taking up space and got a few bucks for my troubles. And I know it'll be made into something else instead of sitting in a land fill for what currently is said to be eternity.
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Old 08-05-22, 09:15 AM
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Usually a dropout can be replaced or repaired but can't say for sure without seeing it and usually not cheap. Where are you located as someone here may have a shop near you that can give an estimate. If you're near Arlington, Wisconsin this place has a good reputation at very reasonable prices. Bicycle Frame Repair- Aluminum (yellowjersey.org) or send them a photo to get an idea of cost. Don't be put off by the 90's style website.
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Old 08-05-22, 09:24 AM
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I had a steel Mongoose IBOC that had a broken rear dropout after many years of hard service. A local welder and frame builder grafted new SS dropouts on for $75 and it had many more years as a SS until it was stolen from my son (the thieves needed to get past a locked fence, locked garage and saw the steel plate in the wall of the garage the bike was U-locked to). As above, we can'ttell without a picture, but it might be possible to reweld it.
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Old 08-05-22, 09:26 AM
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RH drop out cracks are among the more common way a factory steel frame "fails" (not that cracks are common, just when they happen it is often there). As mentioned there are ways to fix this from a simple gusset, through welding the crack up and then complete drop out replacement. If welding is considered make sure there is no filler (most likely a brass/bronze) anywhere near the weld as welding and brass don't like each other.

It would be interesting to see a couple of photos but I've seen enough of these cracks to think I know what a photo would show. Without 10 posts the OP will have to either link us to a third party photo sharing site (I use Flicker) (and type in the link with "@" spelled as "AT" and "." as DOT" to get around the auto censorship this site uses) or post a shot to the gallery and ask one of us to repost that photo here.

By the reference of kilometers I suspect the bike is not in the USA. I would have hoped that if the dropout was cracked at the time of purchase that it would have been noticed long before those 1000K and been attained. Andy
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Old 08-05-22, 09:29 AM
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Originally Posted by 2old View Post
I had a steel Mongoose IBOC that had a broken rear dropout after many years of hard service. A local welder and frame builder grafted new SS dropouts on for $75 and it had many more years as a SS until it was stolen from my son (the thieves needed to get past a locked fence, locked garage and saw the steel plate in the wall of the garage the bike was U-locked to). As above, we can'ttell without a picture, but it might be possible to reweld it.
Too bad about the stolen IBOC (although I'm impressed by the effort made to steel it, makes one wonder if they knew the bike was there already...). I still have my Tomac Signature (1988 model) and would refinish it if I could source decals). Andy
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Old 08-05-22, 12:12 PM
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Ok thank you all for the quick responses! It sounds like it is doable, I'll just have to find someone willing (I think I might know a guy). That being said I dont think I'll get around to it this year.

If people want photos I can figure out a way to do that. But, the crack is right at the top of the 'U' shape of the dropout, on the 'upper' side (away from the derailleur).

Also, I am in Ottawa btw.
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Old 08-05-22, 12:50 PM
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Old 08-05-22, 12:59 PM
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OK,
So your break is a good distance away from where it is brazed, and you should be able to weld it without damaging the brazed joint. Some people will use a damp rag to prevent overheating.

I'd probably just grind in a deep V, then weld it up. TIG? Carefully cutting/filing a gusset to go in the triangle is a good idea, but may not be vital, and would certainly increase the heat affected area. You'll do best if any welding is ground back flush with the machined part of the dropout.
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Old 08-05-22, 01:42 PM
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It's fixable. You need a bike welding frame guy, a pro that knows why and how to manage heat. There was a total of 40-50 seconds of welding, MIG IIRC, 3 or 4 seconds at a time, with 5-10 minutes of cleanup and filing inbetween. The paint was fine 1 cm away from the weld!


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Old 08-09-22, 09:39 AM
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Originally Posted by CliffordK View Post
OK,
So your break is a good distance away from where it is brazed, and you should be able to weld it without damaging the brazed joint. Some people will use a damp rag to prevent overheating.

I'd probably just grind in a deep V, then weld it up. TIG? Carefully cutting/filing a gusset to go in the triangle is a good idea, but may not be vital, and would certainly increase the heat affected area. You'll do best if any welding is ground back flush with the machined part of the dropout.
CliffordK beat me to my answer, i will add that after "v"ing and cleaning the area around the crack, I would try to find a small body or welding shop to do the welding/brazing....more cost savings.
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