My "cross" frame really doesn't have much clearance, even for 700x33s and I think I'll probably saw holes in it if I ride in in proper gritty mud (annoyingly there's quite good clearance where a 650 tyre would go but I'm sticking with 700)
Course, I could change frames but I really like the way it rides and, well, slightly fancy trying this - either myself or more likely getting somebody with sensible equipment to do it
Anyone know if it's feasible ? (it's an oldish airborne if that matters)
It's certainly possible, whether it's wise or not is a different matter entirely.
I'd be going 650.
That said, I had my oval steel chainstays squashed in exactly this way (by a pro frame builder) and they've been fine for 8 years.
The "secert" is to have something cylindrical to make the dimple. Apparently.
indeed - it's pretty close to the weld which seems the major issue to me
it’s an oldish airborne
As reputations go, there's isn't the best for robust titanium. I think I'd replace the chainstay rather than dimpling it.
Have you asked a framebuilder their opinion.
I ride a Van Nicholas Amazon (follow on from Airborne Carpe Diem) that has loads of clearance. When I get home, I'll take a photo of the chainstays so you can see how it's been done with that.
As Al says though - look at 650B. I'm currently using WTB Byways.
thanks scotroutes, mine is a carpe diem - are you suggesting that it looks doable in-situ ?
Sorry for the delay.
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[url= https://farm2.staticflickr.com/1940/43829338910_ae3df9e346_c.jp g" target="_blank">https://farm2.staticflickr.com/1940/43829338910_ae3df9e346_c.jp g"/> [/img][/url][url= https://flic.kr/p/29M3Pt5 ]2018-10-31_11-12-09[/url] by [url= https://www.flickr.com/photos/druidh2000/ ]Colin Cadden[/url], on Flickr
Cheers. Yours looks much more "right" than mine - it's as though they used 26" wheel stays on mine
I was looking last night and it seems awful close to the little bridge to be exerting significant force on it. Looks like it's back into semi-retirement as a winter frame then ... 'til I become a tourer
The problem with trying to manipulate / cold form a tube is to avoid a crease, because it's likely to lead to micro-cracking / accelerated failure. Titanium is also incredibly resilient to plastic deformation - you'll have to manipulate the tube well beyond the depth of 'dimple' to get it to stay - I'd want to do it progressively and controllably with a big fly-press, not just squishing it in a vice and hoping for the best.
The cost / effort of replacing the stays on the frame would be prohibitively expensive in comparison to a new frame.
I'm running that 650x47 at the moment and the dimples are just about perfect (i.e. in the right area). A larger 700 tyre (say Nano 40s) gets very close to the bridge. Close enough that the mudguard bolt could cause a problem.
You're right to worry about the tyre touching the frame and eroding it; titanium is a weird metal and seems to gouge and score easily but is hard to cut. I once had a fattish tyre in my Global and the very edge of the tread managed to rub on the inside of the chainstay for no more than a few minutes until I realised. The combination of speed and wet grit eroded a deep groove and would have cut clean through if I hadn't realised.
Would helicopter tape help?
Not sure I would want to risk it. I had a Van Nic MamTor with dimpled chainstays. One side cracked along the top at the stress point. I noticed the Tuareg they replaced it with FOC doesn't have dimpled chainstays.
It would be very difficult to modify the stays in situ, and uneconomical to replace. I wouldn't bother to be honest (and I work for Enigma). In a steel frame this might be possible but titanium not so much.
Doesnt seem like the best idea.
If I was going to do it I would make something like this
