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Dented Titanium Seat Stay

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Dented Titanium Seat Stay

Old 07-12-23, 05:47 AM
  #1  
thegruyere
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Dented Titanium Seat Stay






I aquired this 1990 Titanium Merlin a few days ago and unfortunately I discovered that the seat stay is dented in a place that was hidden by a sensor. How serious is this dent? Is it safe to ride the bike with it? Can it be fixed and is it worth fixing it?

Notes: I bought the bike from the previous owner directly, not using ebay, and he doesn't want to take it back.

I asked a titanium bike repairer who said the only solution he can do is to replace the seat stay but if it was his bike he would ride it.

Two of my friends, mechanical and structural engineers seemed to agree that: "1st: the damaged cross section is small; 2nd: it's compressive load, less susceptible to fatigue failure, so if any crack initiates, you will see it; 3rd: Titanium is strong, likelihood of structural failure is low"

I'm leaning towards riding the bike while keeping an eye on the dent but I wanted opinions from this forum first.

P.S. The frame was confirmed by Tom Kellogg to be fabricated in about Dec 1990.
​​​​

Thanks
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Old 07-12-23, 05:58 AM
  #2  
Kai Winters
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Not having buyer protection is always a toss of the dice and you lost.
Put a flashy red light over the dent and try to forget about it but you never will...
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Old 07-12-23, 06:43 AM
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unterhausen
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Put the sensor back.

Not sure why you would need a sensor there though, seems fraudulent. I assume you got some compensation for that?

I think you can ride it without issue. I would certainly be annoyed.
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Old 07-13-23, 06:39 PM
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Originally Posted by unterhausen
Put the sensor back.

Not sure why you would need a sensor there though, seems fraudulent. I assume you got some compensation for that?

I think you can ride it without issue. I would certainly be annoyed.
Definitely got burned. Funny the sensor just happened to be right over the dent.

I would fill and level the dent and put a small wrap of carbon over the spot and then another "sensor" over that.
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Old 07-13-23, 06:58 PM
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That looks to me like a dent that could be taken out (actually reduced a lot) with blocks. There's a word for those blocks that is slipping my mind now. If it could be done, I'd bet Dave Levy at TiCycles would be the perfect guy to do it. He knows titanium inside and out. One of the early builders. Repairs is one of his specialties. Titanium so no paint to damage. He also probably knows several other approaches.

https://www.ticycles.com/services-overview

And like his website claims, I've seen frames from all the good ti builders at his shop. Some of the best builders routinely refer repairs of their frames to TiCycles.
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Old 07-13-23, 07:20 PM
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unterhausen
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I don't think you can use a block on a tapered stay though. Unless it's an optical delusion and those aren't tapered
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Old 07-14-23, 03:48 AM
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Originally Posted by unterhausen
I don't think you can use a block on a tapered stay though. Unless it's an optical delusion and those aren't tapered
Yes to illusion, they're untapered.

+1 on Dave Levy, he's the best. (Disclaimer: I used to work at Ti Cycles, 26+ years ago. No connection now though, I don't get kickbacks!) He probably won't be cheap though.

Persoanlly I'd just ride it. In my estimation, likelihood of it ever causing a real problem is nil. And if it does, Dave can fix it when that day comes.

Mark B
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Old 07-14-23, 04:39 AM
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Safe to ride, now you have a bling beater that you don't need to baby or worry about. You got off lucky that the seller wasn't hiding a crack. Take that experience into your next potential purchace, and in the meantime, enjoy your new to you bike.
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Old 07-14-23, 05:11 PM
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Might be possible to CAREFULLY drill a hole through the exposed face of the drop-out (or tube cap) that covers over the lower end of the dented seatstay. Start with a smaller hole that is perpendicular to the surface of the cap then slowly and carefully drill & grind to elongate hole out to exactly match the ID of the seatstay tube. Then, fabricate a steel mandrel that just fits inside the tube and use that to hammer past the dent to push it back out from inside. Once all done, the drilled hole in dropout could be re-welded shut if desired or just leave open.

Last edited by GrayJay; 07-14-23 at 05:15 PM.
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Old 07-14-23, 08:59 PM
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I would be more worried about the 30+ year old aluminum fork. Might be a idea to replace it.
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Old 07-14-23, 09:03 PM
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thegruyere
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Originally Posted by Atlas Shrugged
I would be more worried about the 30+ year old aluminum fork. Might be a idea to replace it.
​​​​​​Planning on replacing both the fork and the stem.
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Old 07-25-23, 08:34 AM
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Thank you all for your responses, much appreciated.
I wrote to Tom Kellogg, he also doesn't think there is any risk of failure:

"That can't be fully repaired because replacing the seat stay is both very expensive and it would have a huge downside of warping the seat tube significantly. There really isn't any risk of failure even though it is a cosmetic annoyance."
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Old 08-01-23, 06:53 AM
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Originally Posted by Canaboo
Definitely got burned. Funny the sensor just happened to be right over the dent.

I would fill and level the dent and put a small wrap of carbon over the spot and then another "sensor" over that.
Ya ha ha not soo funny
Yes, if not going with an expert TI fix then a carbon/epoxy wrap would be extra support and hidden again under another sensor
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Old 08-02-23, 01:40 AM
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It may not be significant at all but will certainly annoy the living crap out of you.

I would embrace it. Put a legit band-aid over it. If anybody asks why there is a band-aid on your titanium bike you can tell them that the bike has a boo-boo there.
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