Shock rate isn't leverage rate. Air shocks are progressive in nature so just about every design to ever use an air shock is progressive. Santa Cruz use shock rate because the leverage rates of their bikes are not ideal which is a common trait of counter rotating link bikes.
If a leverage rate falls from 2.8 to 2.3 it's progressive. Fact.
When people are having a technical discussion without agreeing on the terminology, misunderstanding will ensue. Fact. I.e., that's why I said "if you're talking about shock rate", because you didn't specify. Now that you said "leverage rate", I know what you're talking about, and hey guess what I agree with your "fact". Head over to ridemonkey to discuss the Santa Cruz leverage rate problem...
In any case, based on the leverage ratio plot on the page djjohnr referenced, I don't think there's any confusion that assuming that plot is correct, that for the bike in question (Enduro Evo), the leverage rate starts off progressive, then reverses near the end of the travel (though it's certainly not that much difference overall, only varying between about 2.8 and 3.05). This would normally be a decent curve for a frame designed around an air shock since as you say, air shocks are progressive by design. This would make that ending part of the stroke feel more linear as it would counteract the natural progressive ramp at the end stroke of the shock. But with a linear shock (coil), that could make it blow through the end of the travel more easily, which is what djjohnr is unhappy with. He's not making it up because of some misunderstanding of leverage rate. We all on the same page now?
The ONLY issue with the dynamics in this case is in cases of extreme rear end flex, you could allow up-down motion to the linkage without actuating the shock. Having it keyed/co-linear like the stock unit basically has the shock acting as a strut to reinforce the linkage (in some very small part).
Maybe I'm misunderstanding, but if you're saying that having the shock acting as a reinforcing strut is a *good* thing, I'm going to have to disagree. That is what the current design does, and it leads to shock failure at the yoke attachment point as described above. This replacement yoke would alleviate that.
@jimw - here you go:
Rotwild R.G1 2014 - Linkage Design. Note, the post is for a Rotwild but if you look at the graphs he shows the '13 Evo as a comparison. As usual ignore the exact numbers, but the overall shape should be pretty accurate. It's pretty damn close to linear overall.
Thanks for that link (I think
). He should put that plot on the page with all the other Specialized bikes. It does look pretty damn similar to the regular Enduro.
I agree it's all about what it actually feels like. When I run the 480 spring it feels great, albeit a little stiff. However when I put the 450 on the first half feels even better, but then it starts feeling really loose when you get deep into the travel. More then anything I'm curious about what the Float X2 would feel like on there. I may buy it and keep both.
Hmm. How much preload do you have when running the 480 vs the 450? I'm running the 480 (well, a custom Ti spring that's actually 475), and I have somewhere between 1.5 to 2 turns preload.
Anyway, you should try that Float X2 and report back.
I actually toyed with the idea of getting an Ohlins STX for my Evo frame. They don't actually make it for the Evo with 180mm travel, but... it's the right eye to eye with a shorter stroke. So it shouldn't change the geometry, but would reduce the travel (and naturally be more progressive). Which wouldn't necessarily be a bad thing for epic AM ride days. Probably not for you though, since it sounds like you don't want to change the travel, just how progressive it is in the latter half of the travel...
