Telemark Talk / Telemark Tips Forum

This may be a long shot but I'm working on a binding design and want to determine how much force the cable puts on the boot. Does anyone happen to know the spring constant of any springs used in bindings?

Ask the nerds over at backcountrytalk.com. Any value is calculable from any other value, but I think we've usually talked about things in terms of spring rate. I've found that something in the range of 100-150 lb/in is a good starting place when designing a binding. You can spend all day scouring the spring catalogs, but really the ones used by 22D, Meidjo, etc were chosen for a reason -- because they are a good blend of adequate spring rate, small-enough OD, and adequate max deflection (aka "travel").

It’s easy to experimentally determine spring rates yourself. All you need are some barbell plates or other items of known weight, some all-thread, an assortment of nuts and washers, and a ruler. Oh, and somewhere to hang it all.

F = kd where F is the ‘weight’, k is the spring rate, and d is the stretch distance. As long as you don’t exceed the yield of the spring it will be linear.

Hang the weights, F, from the spring and measure the stretch, d. Do this for several different weights. Plot them and they should fall on a straight line, or nearly so. Calculate the slope of the line, k, and that’s your spring rate. I’ve done this for motorcycle fork and cushion springs and it works great.

I dunno if it's blasphemy to post links from the other, other, forum but here are some places to start.

https://www.backcountrytalk.com/forum/b ... try-thread

https://www.backcountrytalk.com/forum/g ... le-springs


Here are the K values I can tell you from experience

kreuzspitze Hard Springs: 124 lb/in
Black Diamond Mid Stiff: 57 lb/in
Back Diamond Rid Stiff: 75lb/in