Entry level builder here with 4 frames so far. Working on #5 right now and realized I made a mistake. Generally I’ll braze the front of the ST to the BB before installing the DT, which I believe is fairly common practice. Well I forgot to braze that part and now the DT is in place and I obviously have no way of brazing the part of the ST that is now hidden inside the DT. Picture shows the area before it was brazed together and I suspect there’s roughly 3/4" underneath the DT that wasn’t brazed. Seems there is very little info online about this, though I found a couple threads that led me to believe some builders don’t even worry about joining that part together. Anyone have any experience with leaving that part unbrazed?
Plenty of factories I worked with in Asia don’t weld that area.
If this bike is for you: I think you’ll be fine (provided you have decent brazing skill). Provided that your brazing technique is decent, I think you’ll be fine. It’s a learning moment. When you’re done riding it, cut it up and inspect those areas.
If this bike is for someone else: Finish building the bike. Cut it up. Inspect it. Don’t let half-assed shit go out the door.
Thanks for the insight. Me and a friend were building this one for him. The good thing is we’re the same height and ride virtually the same setup so I’ll likely just keep this one for myself to put some testing into and get a properly built one going for him.
If a crack or failure does occur I’ll post it up here, just so others have some reference if they’re ever in this situation.
Unfortunately, it’s impossible to prove something won’t fail. In this case, I think the junction is perfectly fine. The DT and ST have quite a bit of overlap.
I cut apart a 90s rocky mountain equipe to make a cargo bike and was surprised to find they hadn’t welded this section either. I brazed it before adding the new down tube but clearly the bike survived just fine for 30 years without it.
