I have a cheap, and I emphasize cheap, single-speed commuter project. It's a late 80s Bianchi Broadway I picked up at the thrift store and resuscitated. I'm going to go back to grad school next semester and need something to put around campus mostly. I don't want to take anything I'd miss when it gets stolen (odds are against me on this )
Anyway, in the process of cleaning it I found two cracks in the frame. It's a steel frame with lug construction. Worst crack is right after the lug on the top tube. The other one is in the same spot, right after the lug, but on the down tube. You can see the top tube damage in the photo below.
The bike is up and running and I'd like to correct these as best I can with the means available to me. I am OK with a MIG and have a Millermatic 175 here at the house along with the usual metal working/prep tools that go with it.
I see a few options:
1 - Not worry about it. Ride it 'till it breaks or gets stolen.
2 - Drill a couple of small holes at the end of each crack to stop them from growing. Clean and prep, then run a little bead over the crack with the mig.
3 - Drill and prep as in #2, but put a little gusset plate over the crack and weld that in place to distribute the load/heat a little better.
I realize both the welded options will put a some heat into thin steel. If I do the gusset plate, I won't fully weld it to reduce the HAZ....I also would let it air cool of course.
Reading up on these forums, it seems that brazing is the preferred method of assembly. We do have an oxy-acetylene torch set at work and I'm sure one of the guys will help me braze on a gusset plate if that is a better approach.
Would brazing on a gusset be a better solution? Any other ideas I haven't thought of that would make more sense?
Thanks in advance for any feedback!
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