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So, I tried to take some brakes off of a bicycle to change my old-style callipers with V-brakes; the results were not good.

enter image description here

One of the "heads" or "lugs" was so caught in brake itself that I managed to torque it clean off of the bicycle trying to remove it. The darn thing is STILL caught inside the brake, it's just not attached to the bicycle any more.

Is there any way to fix this sort of damage or is the bike a goner? I assume I need to find someone who can weld.

Also, how did a tube inside of another tube get SO stuck that it took all of my strength to even start moving it with tool?

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  • Yeah, looks like it might have cold welded itself. You should have tried heat or a penetrating oil. A frame builder could reattach the bosses but you may be SOL. You might think either of attaching caliper brakes or using an adapter and a rear disk brake. This is the rear wheel so you have more options.
    – RoboKaren
    Commented Apr 11, 2018 at 0:27
  • I DID use penetrating oil. I thought that using heat might expand the brakes, so I left it in the sun a couple of minutes; how else might I have tried heat?
    – user1833028
    Commented Apr 11, 2018 at 0:29
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    Propane or butane torch - you need to differentially expand the metals. The little creme brûlée torches are good for this.
    – RoboKaren
    Commented Apr 11, 2018 at 0:32
  • What would the technique be for trying to reapir this metallically? Would it involve reattaching the cylinder part or would you have to weld off the whole kit and kaboodle? Does this take some special skill, or could it be put back on with general welding knowledge....
    – user1833028
    Commented Apr 11, 2018 at 0:35
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    They are not removable, otherwise the threaded portion of the stud would be visible in the photo's distant brake boss. Also, the entire stud would be mostly solid, in order to provide enough threads for the boss to grip when it was fully threaded in.
    – JonR
    Commented Apr 11, 2018 at 5:58

2 Answers 2

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Problem Solvers makes a kit that is usually worth a shot to see if the post is completely shot and needs re-welding:

Cantilever Stud Repair Kit

You could probably even fabricate one yourself if you could find the right tubing diameter. We used these frequently at the shops I managed, and they have a roughly 50% success rate. Having them work properly is largely dependent on ensuring that the base of the original stud is cut and filed very flush and almost perfectly perpendicular to the bolt's orientation.

If you install it successfully, great! You've only spent a few dollars, and you've got the bike back up and running. It's much cheaper than trying to get a new boss re-welded on.

If this does not work, it's only a few dollars spent, and you can explore alternatives.

Installation Instructions

I would not really even recommend trying to have it re-welded, because it's pretty difficult for a welder (unless they're an experienced framebuilder with the correct jig setup) to get the boss lined up to the point that the posts are equidistant and oriented to exactly the same angle.

Your second best option would be the long-ish caliper brake that RoboKaren suggested. Don't even consider those disc brake adapters; the chances for failure or misalignment (that leads to failure) is very high. Disc brakes are not a one-size-fits-all solution, and require much more precision than those adapters can supply.

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That V-brake mount is knackered and it’d be too expensive to reweld it. As a last resort you can see if you can use a bolt extractor and a lot of heat to get that boss fragment out but it’s gonna be tough and there’s a good chance your boss was press fit or welded and not screwed in. If you are able to get that fragment out then you can replace it with a cantilever stud:

cantilever

The cheapest and most realistic option is to mount a caliper brake on your seat stay bridge. You keep your old wheel. You may need to find long reach calipers, modern ones may have too short of a reach or aren’t wide enough for your wheels.

caliper brake

Another option though much more expensive is to get a rear disk brake conversion kit. They attach to your rear triangle. They’re more expensive as you need the conversion kit, the disk brakes, maybe new brake levers, and most likely a new wheel that is disc compatible. It’s your rear wheel so you lose traction before anything else so you won’t brake faster but you’ll at least look cooler.

disk brake conversion kit

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    Disk conversion kits are generally rubbish IMO, and OP would be better at buying a fresh bike. The other two suggestions are great.
    – Criggie ♦
    Commented Apr 11, 2018 at 7:57
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    Disk brake conversions are a hack, don’t work on all bikes, and don’t always work well — but there are people who’ve gotten them to work, so they’re not totally trash. Having it on the rear wheel reduces both the criticality of the brake as well as it’s responsibilities. I’d never recommend this for the front but for the rear it’s a workable hack if he can get it to work.
    – RoboKaren
    Commented Apr 11, 2018 at 13:53
  • I'd be worried about the other three canti studs breaking now. Perhaps a close inspection of brakes under bright light after a disassemble and degrease would be the first step. I'd also eyeball every weld on the frame too.
    – Criggie ♦
    Commented Apr 12, 2018 at 3:27
  • A hub brake puts more stress on a frame than a rim brake, and it puts that stress in a totally different spot. The frame needs to be designed to withstand this stress, it's not just a matter of having the mounting holes in the right place.
    – Mike Baranczak
    Commented Apr 18, 2018 at 2:27

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