1" Ti chain stays

[progetto]

To those who build in all things Ti, pro's and con's to 1" Ti chainstays instead of 7/8" for road racing frame. Thinking along the lines of extra stiffness chain stay enabling to use thinner diameter seat stays for added comfort. Feasible or not? Interested in opinions.

[hampco]

kent eriksen has the 1" stays dialed on his frames but they do need a fair amount of massaging to get them to work.

they sure look nice!

[Tom Kellogg]

We've been using 1.0" Ti chain stays for somewhat over ten years now. In order to give sufficient heel clearance, we do taper them down to 3/4" at the dropouts. The Merlin version started with our stay design, but then they were "S" bent in a die. Used properly, they make Ti frame drive trains WAY stiffer. K?

[progetto]

Tom,
Do you use them on every Ti frame or only frames for heavier or stronger riders? Does it effect the overall comfort of the ride, I know that all of this is very subjective.
Bill

[Tom Kellogg]

Bill:

At this point, we seem to be using the 1.0" stays on about 60% of the frames. They make frames too stiff for some customers and some purposes. They have no effect on comfort, only drive train stiffness. Helps?

[darren crisp]

.... we do taper them down to 3/4" at the dropouts.

Tom, how are you getting these down to 3/4" at the d.o.? Swaging? I'd like to do that on some frames but I don't have the capacity/volume to have this done.

thanks,
darren

[Tom Kellogg]

ABG (Merlin) produces all of our materials for us, so they do it. Their swager has a number dies that they have created over the years for different tapers for both Merlin and Litespeed. PM sent.

[Mark Kelly]

Tom, what's the contractile strain ratio of the swaged part of the chainstay?

[Tom Kellogg]

Mark:

Interesting question. Since we did not encounter any increases in tube failures in our initial testing of the 1.0" stays back in '01, we didn't bother having the swaged tubes tested for grain orientation. Since wall thickness is hardly effected during the swaging of 3/2.5 to the degree that we are reducing diameter, one can assume that we are having low CSR increases and that there will tend to be somewhat more of a circumferential texture orientation than there is in the nominal section of the tube. In the real world, there seems to be no real effect from the changes in the CSR but at least in theory a mid range increase in CSR does increase notch hardness. Not that it seems to matter since we have never had a 1.0" stay fail. I didn't answer your question directly since I can't give you a number without having had the post-swaged tubes tested. And of course, the small end will have a different CSR than sections that have been worked less. Helps? (at least a little)