TurboTrueno

Hey guys. Been lurking and searching for a while. I have welding experience but have never worked with bike frames or CrMo at all.

I have an old frame I am going to restore. It is a fixed-gear conversion and will be staying as such (it has a brake). I would like to remove the now-vestigial shifter bosses from the downtube, as well as the cable rings from the top tube.

The tubing is Columbus SLX from the early 1980s. I have googled and it seems this is just 4130?

How should I go about welding over these? I thought it might be a good idea to TIG braze, and put less heat into the frame, due to the gauge of the metal, its age, and the seemingly non-structural nature of the hole locations. Or is a normal ER70S-2 the way to go? 80S-2 for more strength? I also see 4130 rods available online.

Feel like maybe I'm overthinking it and any of the above would be just fine for some tiny holes like this. Also hoping I luck out and the top tube cable rings can just be ground off and left alone..that would be nice

Thank you guys for checking out my thread. Please feel free to correct any of my assumptions, I am in the dark here...

niknak

Those parts are likely silver brazed on. Hit them with a torch with the frame positioned so gravity does its job.

Andrew R Stewart 

"Holes"? I sure hope that frame was made so that the braze ons you mention don't have any holes in the tubes The usual advise with removing braze ons is to do so w/out heat by grinding/filing/sanding.

The steels used in frames back in the 1980s was very close to 4130. I strongly suggest practicing on thin wall steel before considering showing a frame your torch, bet it a TiG or an OA one. Andy

guy153

Yes as others have said they should just drop off. But if you don't own that kind of torch very carefully grind them and then sand or file the last bit by hand. If you were filling a hole then yes TIG braze is better IMO. Less heat and distortion and easier to build up in a blob to bridge a gap.

dsaul

Never use 4130 filler to weld 4130 bike frames. ER70S2 is fine, but ER312 stainless filler is better. As, mentioned, those mounts should be brazed on and can be removed with heat or ground/filed off. Be very careful with any grinding/filing.

TurboTrueno

Thank you for all the great replies!

Total bike newbie here, I googled "removing downtube shifters" and everything came up with ugly holes underneath. If there are no holes then that is great news

I will assess it in late autumn when I stop riding it, plan to restore it during the winter

unterhausen

People used to sell amusing covers for bosses. There certainly were some bosses with holes underneath, but not all of them.