Cracked dropout
 

Bought the bike NOS four years ago...its late 80s 4130 of Taiwanese production. Been using it to commute year round since getting it.

What are the options here? Can I get more life out of this thing cheaply? I like the frame but its a bit banged up and has a crack in the rear triangle :)


http://bikeforums.net/attachment.php...hmentid=442662

The break is very close to the tube, so IMO welding is probably out. But it is repairable by brazing. Any decent torchmak should be able o do this for you at low cost if you don't mind burnt paint and some down and dirty repaint of the rear triangle. A nicer job would b to replace the dropout, but that's a bit more complicated since it loses the positioning.

BTW- just guessing by the photo, but I wonder if the rear triangle width was not matched to the hub. If so, you need to correct that before brazing, or it'll just break again.

A frame maker* could braze-in a new drop out. I wouldn't worry excessively about hanger alignment, you can correct minor issues later by cold setting, bending, the dropout.

You will damage the paint but mask off the surrounding area, prime and paint. Enjoy the ride.

* A bicycle shop will know of or handle repairs of this sort. You can buy as little or as much service as you need. Brazing talent can also be found in repair shops so if you live near the marine industry or auto shops, there's a pretty good chance you can find someone with the talent to help you out. A lot of businesses love these little cash transactions.

Hanger alignment isn't the issue. Dropout position and alignment is. Once it's pulled apart the repair would call for a fixture to ensure that the new dropout is in the right place, especially the height and parallelism to it's mate so the rear wheel will be square.

If it's left in place, position can be established by closing the break properly.

The difference is that the quick repair is straight torch work and can be done by just about anybody, like a car, motorcycle or farm tool mechanic, and the second calls for some framebuilding skills. It's also the difference a quick and cheap job, and something that might cost more than the frame justifies.

I'm guessing it looks off because he's pulling the break apart to show us. It looks like the upper section may have been cracked for a while.

Very possibly. As always, people can factor their specific knowledge into the consideration of any advice. If the crack naturally closes close to evenly, then all is good in that regard.

Mere brazing the crack closed will be most likely a short term repair. Getting the two faces completely clean will be the first challenge. Remember that brass (or actually bronze fillers) are not as strong as the steel is. So unless a build up is done the braze will be the proverbial weak link. And if there were any contributing factors (like misalignment or bent/broken axles) that are not fully dealt with...

Replacing the drop out is by FAR the best repair, and the only one I would consider. Here though there is likely to be much more work and material involved. If a exact dup of the drop out can be found (and will probably be found as a pair) then the amount of stay mods will be minimal. If not then the stay ends (both seat and chain) will have far more modifying to ensure proper wheel placement for alignment as well as engagement to allow for good brazing joinery.

I have done a number of these repairs over the years, this breakage point is the most common for a rear drop out. There have been a few times where the lining up of the stay ends. the drop out tabs, the two slots (and therefore the wheel sitting properly in line) just didn't work out and both drop outs ended up being replaced.

I love it when those who don't do this kind of work say it's a fast and painless job. If the break had been in another location in the drop out I would have a far different view. Andy.

FWIW - I have done this kind of repair, but it's not that we disagree. It's a question of economics. The frame itself doesn't warrant doing the right repair, which I also alluded to in my first post here. So the OP has a few choices.

1- do nothing and trash the frame, which might make sense
2- spend the dough with a frame builder for a proper repair, if he feels the frame warrants that kind of investment.
3- do a "down and dirty" repair, which isn't the "right" answer, but can buy him more time with this frame. There is some room to work with, and might be some options for a stronger, though not strong as new, repair using some added steel along with the braze.

Sometimes a lousy, but cost effective solution is the best of the options available. Unfortunately, it's too often rejected outright, and something that could have been salvaged gets trashed instead.

Francis- It wasn't you that I was talking about directly. But your reply did fall into the radiated zone of my comment.

I have a frame in my basement right now to do a repair of a repair. The stay top fractured just behind the sloping plate's leaving the lug. The rider took it to a friend and got it brazed together with no added reinforcement or extra filler. Didn't take long for the crack to return. This time the rider was looking out for it and the stay is still attached by the top plate's thickness only. This will make my repair that much easier as the locating/alignment is already established (and yet to be documented on the surface plate).

But this is just one more example of a down and dirty job that didn't address the issue fully and didn't last for long. After a while of seeing this kind of get by repair I just don't bother to even suggest this sort of thing. Yes it's my standards but if I'm holding the torch it's my choice to do it right or pass. I realize that it's the rider's choice to find another torch holder. Andy.

That's OK, I didn't take it personally. My point is that there is sometimes a place for meatball surgery. It creates a middle ground between "costs more than it's worth" and scrapping something.

If you read the OP it asks the question "can I get more life out of it cheaply?". That's what I answered, and why I suggested the not so good, but can be done cheap repair option.

Correct, I am pulling it forward in the photo. A period correct 126mm hub is/was being used.

Indeed most of the break is quite visibly rusty and only a small portion is fresh metal.

Ive addressed the problem for tomorrow's commute.

http://bikeforums.net/attachment.php...hmentid=442704

If it is actually 4130 Chromoly, it can be tig welded, and possibly has been welded (mig/tig).

It looks like that is a cast Campy-Style horizontal dropout (complete with the set-screw). At least generally not found on department store bikes.

What type of bike was it on? Do you have photos of the whole bike?

Is the bike brazed and lugged or welded? Some dropouts are also welded in place.

Anyway, if the frame is as cheap as you indicate, then it won't be worth paying "shop rates" to repair, and end up with a repaired/repainted (or touched up) frame. Strip it and move on.

If you can do the repair yourself, or have friends or family that could do it, that would be another question.

I'd lean towards doing a quick and dirty tig welding unless the bike seemed to have significant value. Or, perhaps donate it to somebody wanting to do something like installing track dropouts on a classic road frame.

I got a seat tube silver brazed into my steel road bike for $40 and a six-pack. It would require careful planning to source the parts, some prep work on the part of the bike owner, and a plan to get some brazing help. If the frame has sentimental value as well as practical transportation value, I wouldn't consider its repair to be ill advised.

Pics of the whole machine and some frame stickers that came attached to it.

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