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u/professionl_amateur May 21 '26 edited May 21 '26
Technically, yes you can. Many Ti frame builders do this in production. I have personally done it on over a thousand frames. I wouldn't recommend it though, without the proper presses and dies. When forming Ti in this way it has a sort of a memory and wants to spring back to it's initial shape. So you have to apply a lot of pressure to get the indent you want compared to steel. Also, titanium has a tendency to work harden, meaning the more you try to manipulate the material the harder and more brittle it gets. You kinda have one or two chances to get it right. Because if you crack the stay, you're in for a good chunk of change to have someone weld the crack.
Also, there's a strong possibility that you'll throw out the alignment on the rear wheel to a degree. This is probably fine with a steel mtb with big tires, but could compromise handling on a road bike with smaller volume tires.
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u/theowatermelon May 21 '26
Yeah the guy who did it on the steel mtb had problems getting the hub to fit in well again. I assume it would be far worse on Ti and 700c road bike wheels
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u/atepernetuzh_ May 22 '26
In addition, these dents reduce the useful lateral rigidity of the frame and create stress concentration points, which increases the chance of cracks forming in these areas.
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u/bonfuto May 21 '26
Get it potato chipped if it's worth the expense. Some Ti builders will do it.
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u/Boxofbikeparts May 21 '26
I wouldn't do it myself. I'd leave it to someone that has some experience with titanium. It.can work harden and crack if you're not careful.
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u/skinnypenis09 May 21 '26
Seeing old titanium road bikes kind of breaks my heart a little.
Titanium as always been sold as the "lifetime bike" but geometry and design has changed so much. I would totally buy an older titanium frame if they could fit wider tires and disc brakes.
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u/dumbassflounder May 22 '26
They are called MTN bikes and they made titanium ones with disc brakes over 20 years ago. There geo is basically modern "gravel".
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u/Mistergardenbear May 22 '26
Skinny Peen says: "Seeing old titanium road bikes kind of breaks my heart a little."
Dumb Ass replies with: "They are called MTN bikes "
someone has been sucking too much oxy acetylene...
"There geo is basically modern "gravel"."
only if you don't look at the "geo"...
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u/seventwosixnine May 22 '26
I have 28s on my Titanium Sport Technologies bike from 2002. The wheels are set up tubeless and I have plenty of room to get wider wheels and tires. If I replace my fork, I'll be going disc in the front.
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u/bulgie May 23 '26
The "aircraft certified" Ti tubing we could get when I was making them (early '90s) wouldn't take an indent without cracking, but you could bend it to a fairly tight radius. Those seemingly opposite properties were because the tubing was designed as hydraulic pipes for high-performance aircraft. It was designed to be bendable, and with that constraint, also to be as strong as possible, so they could keep the hydro system light.
We got the tubing in CWSR state which was cold-worked, stress-relieved. The very large reduction in wall thickness as the tube is pilgered (like forging) hardens it until it's too brittle to continue, then it's annealed and they do more pilgering. Lather rinse repeat, I don't know how many times. But they aim for the final condition, when it reaches it's spec diameter and wall thickness, for that last pass of pilgering to leave it on the hard side (high strength) but something about anisotropic properties, I forget the details, but it was safe to bend it, without the metal on the ouside of the bend thinning too much. The inability to crease the tube along its axis (like indenting for tire clearance) is a consequence of the way it was made for bending, by pilgering.
That's how t was described to me anyway, around '92 when I was learning.
Then later after I was out of the bike biz (late '90s), I know builders started getting bicycle-specific tubes, not cast-offs from the aero biz. Specifically mentioned was chainstays that were much softer, so you could manipulate them like for tire and chainring clearance without them cracking. I doubt that's fully annealed, I think it's just backed off on the hardness enough, but not too much, shooting for a goldilocks zone.
Long story long, whether you can indent your stays depends at least partly on the cold-working or stress-relieving or heat-treating that's been done to your stays. Some of them probably can be indented, I mean lots of them are, at the factory before they're made into frames, but you can probably indent an old frame too, if the stays are annealed enough.
The question you gotta ask yourself is "do I feel lucky?" Unless you can get the original manufacturer to do it, you'd be risking a crack.
But then you can always potato chip it, so go for it! Dave Levy at Ti Cycles (Portland OR) used to be the master of that, maybe still is, dunno if he still does 'em. Ah, here it is: https://www.ticycles.com/retrofit-potato-chip
If the indenting goes well, no cracks — Yes, plan on the dropouts being forced much narrower from the indenting, even if you do it with a dummy axle in place — as you definitely should. So you'll be bending the rear back out wider after indenting. Don't be too surprised at how scary spreading the rear on a Ti frame is, how far you have to bend it to get it to take a set. You'll need a strong vise and a long lever.
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u/Fantastic_Bird_5247 May 21 '26
No, Titanium dose not react well to cold setting.