Now to walk the frame with a pin to see if the places that don’t look brazed actually are but are lying to me. And then to braze on a couple of fender eyelets, write “RADIATION HAZARD” on every tube, and heave ho out the door.
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how dumb would I be to braze disc tabs onto my '90 stumpjumper rear triangle? The stays look beefy as fuck.
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Should be fine if that’s what you want.
It’s totally unnecessary and I kinda want it but more importantly it will annoy the fuck out of my roommate. So I think I should definitely do it.
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Do it
I’m going to do it with a nishiki alien
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The dropouts alone probably weigh a pound
Not dumb at all. I brazed disc posts onto my 90(?)s Talera and that machine’s been fine since then, including some not-agile-cuz-front-rack™ forays up into the mountains.
not a huge deal even with spindly stays
your safety would come from adding a little brace in the rear triangle to support it
So I shouldn’t add a brace? I can imagine how that could cause problems but can you explain a bit so I don’t feel like such an idiot. I’m a serial DIYer but as such I don’t often get the luxury of knowing why I shouldn’t do something.
The rear wheel will break loose before it can apply enough leverage to buckle the seatstay.
I’m actually not that worried about it because I’m a very heavy handed front brake user. But in emergency situations it’d still be nice not to fold this frame.
That said, I’ve been riding this bike for two days with no brakes and made it work (brake cable slipped early yesterday and I forgot about it today when I decided to ride it to work).
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The old mtb that became my cargo bike had tabs and a brace added. I’ve come to a nice stop on long downhills loaded with groceries and my 260lb self plenty of times. I say go for it.
Fatigue is the real problem, and it’s cheap insurance since you’re already brazing in that area anyway. Plus you can use pretty much any size or shape of steel material that can take some compressive load. If you don’t it might not ever fail within your dithering window, but if you do add one it will essentially never fail.
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sorry I wasn’t clear: you should always add the brace
Orc you’re mistaken about the failure mode, it’s very common for the chainstay-dropout connection to fail
it happens often enough JRA to 80s steel bikes on the DS dropout, and is extra likely to happen on the NDS in an unbraced disc conversion
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I know about that failure mode (I’ve re-dropoutted a frame that suffered from it), but pictures of it happening on the NDS side are almost vanishingly rare compared to DS failures. The bike failures site at pardo shows a wide variety of failures, and the one I’ve found of a NDS chainstay/do failure has the comment that it failed when traversing a rock garden. (edit: found another where the entire tip of the NDS chainstay+seatstay+dropout snapped right off! That’s a fun one to look at.)
There are plenty of pictures out there of jackknifed disco fork blades, not so many of folded disco rear triangles.
When I worked at VooDoo we built a small run of prototype Scandium mtb frames without braces and they all broke above the disc mount in a short manner of time. Probably the worst case scenario (weight weenie aluminum mtb) but that failure mode is a very real thing.
Ahhhh, thanks man.
Not building so much as shipping today.
It’s out of my hands and into the demolition derby that is ground shipping now.
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Better not unglue itself en route here
I am looking at getting a TI bike built. Very early days, gravel/cross/communter/low-level bike-packer rig. Anything I need to know about the T47 BB standard? I dont really care about Q-factor.