Length, diameter, etc is all I need, so that will be an enormous help. I just want to know if springs meant for a Gen 2 will fit into the Gen 3 forks without modification to the springs, forks, or need of spacers.
I understand. I don’t ride hard and I’m fairly lightweight. I’ve put progressive springs in my past KLR’s (two Gen 1’s and one Gen 2), and I like the way they feel. They just work for me. I’m hoping the Progressive springs for the Gen 2 will work.
So you put Progressive springs in your 22? That’s great!! Where did you get the springs? I found them at Procycle, but it’s just the springs.
What else are you looking for?
Nothing. Sorry. I got confused for a second when you said “kit”.
So, Progressive Gen 2 springs will go into the 22’s without mods needed?
Wow! No wonder that front fork is so stiff for me. I’m only 155 lbs. In the past, and was able to just replace the springs without changing the spacer. We’ll see what happens with this one. A million “thanks” for the update!!
If you had some help, you could get a pretty accurate spring rate by standing the spring on a stable, level surface, semi-balancing a known weight on top while you stabilize it and having someone measure the compressed length to compare to unloaded. Or, fasten a fork tube vertically to something solid, drop in the spring and spacer, pull the upper tube so it's above the spacer, then put your known weight on it (the heavier and more compact, the better). Let it compress the entire assembly, carefully remove the weight, then measure how far the spring extends above the top of the tube when unweighted. You'd have the uncontrolled variable of stiction, but it would be close enough for government work.
Was going to tell you to be sure to have video rolling when you tried it, but decided to just try it myself, lol. I clamped the lower fork tube to a low shelf on my welding table, then clamped a stop block to the upper tube so it was stoppered against the table top in a semi collapsed state, which took stiction out of the equation. The assembly was plumb in both directions as measured by a professional quality torpedo level. I dropped in a spring and put the standard spacer on top. with a piece of 2x6 resting on the spacer as a cushion, and after bouncing it to settle it, it measured 179.5mm from the top of the fork tube to the top of the spacer. I then centered a 16.56kg cement block on the top, again bounced it to settle it, and got a reading of 136.5mm. I repeated the process 5 times, getting consistent measurements each time. Taking 16.56kg divided by 43mm yields a spring rate of 0.38kg/mm. Then I swapped out the spring for the one from the other side of the fork and repeated all steps. That spring (which was 2.3mm taller at the outset) dropped a repeatable (again, 5 times) distance of 40.5mm for a spring rate of 0.41kg/mm. It may not be spring rate test bench accurate, but I'd bet its single decimal accurate. This is a 20k mile '08 with, to the best of my knowledge, OEM springs (which the measured rates would seem to bear out). It can be done, along, and it's actually not that difficult. The only downside is that now I know for certain that I need to purchase stiffer springs.
My measurements didn't take long at all, but that speed was predicated on already having the forks off of the bike for a fork oil change. Actually, it's easier to 𝙚𝙨𝙩𝙞𝙢𝙖𝙩𝙚 spring rate using a formula but the actual rates will depend on consistency in both manufacturing process and metallurgy. I'm sure my factory installed springs were estimated to be identical (with a spec of 0.40kg/mm), yet even my fairly crude appearing methodology has revealed an actual 𝙘𝙖𝙡𝙘𝙪𝙡𝙖𝙩𝙚𝙙 rate that is demonstrated to have subtle yet quantifiable differences. It'll be interesting to plug the measurements of my springs into a formula and see if the small differences in free length yield rate differences similar to the demonstrated actual differences. Of course, none of those subtleties will matter to a KLR. If you installed a 0.40kg spring in the left fork, and a 0.60kg spring in the right, it would probably ride like a bike with a pair of 0.50kg springs in it (though it might increase stiction and produce a noticeable hinkiness in a Gen 1 with its more flexible forks). The engineering part of my brain says that if I were a race tech, especially on a road bike, I would be installing springs of identical length and measured rate in both forks, in order to avoid inducing fork stiction/changes in wheel camber and forward alignment that could result from bowing of the fork tubes caused by unequal rates.
