Mountain Bike Reviews Forum banner
21 - 34 of 34 Posts

·
Registered
Joined
·
545 Posts
Glad someone is doing it. I designed almost the exact same link, and declined to make it since even at quantity, it would have cost $200/ea to bring it to market and make any money on it, and I wasn't motivated/patient enough to deal with machine shops that weren't in my area where I could QC stuff before taking delivery.

I'd buy one. 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).

It's a silly design no matter what. I think they could easily make a standard eyelet work and account for whatever lack of reinforcement that might come with it through other methods. There are a number of shocks that I would prefer to run on that bike. DVO Jade, Fox RC4, X-Fusion shocks, etc. etc. etc....
 

·
Registered
Joined
·
1,544 Posts
No it isn't, if you're talking about shock rate at least. See:
Shock Rates V 1.0 - NSMB.com
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.
 

·
Elitest thrill junkie
Joined
·
38,817 Posts
Considering you can get...
Cane creek DB air
Cane Creek Inline
Monarch RT3
Vivid
Ohlins STX
Ohlins TTX
Fox shocks which fit the Standard link, seems a waste of money to me and voids your warranty.
Except you can never sell the shock because no one wants to buy a shock that only works on one bike.

Not being able to run a standard shock also prevents you from buying a used model and sending it to avalanche or push for a custom tune, which will vastly outperform an OEM shock.
 

·
Elitest thrill junkie
Joined
·
38,817 Posts
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.
People are confusing spring rate with leverage ratio. Spring rate (lbs/inch) will go down with a falling rate or digressive suspension design. Spring rate increases (lbs/inch) with a progressive rate. Leverage ratio (shock travel vs wheel travel) will decrease on a progressive design.
 

·
Registered
Joined
·
765 Posts
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...
 

·
Registered
Joined
·
589 Posts
Discussion Starter · #27 ·
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...
I'm only running the minimum 1 turn required, which gives me the recommended ~28% sag. I get ~33% sag with the 450.

I was trying to replace my medium frame with a large, however that led to a bad used frame purchasing experience. Now it looks like I'm going to buy one of those Knolly Delirium abominations. If anyone is looking for a TTX for their EVO mine will be available soon.
 

·
Registered
Joined
·
765 Posts
Sucks about the used large frame not working out. Before you pull the trigger on the Knolly, did you try running the 450 with say 2 turns of preload, or whatever is enough to get the recommended sag instead of 33%? I bet it will feel better, maybe get rid of the end stroke weirdness you were having.
 

·
Registered
Joined
·
4 Posts
A common misconception in the bike industry. Falling rate is actually progressive.
That´s probably true, but I think we all know, what he means. The leverage ratio increases towards the end, so Enduros are more likely to bottom out with high volume shocks. That´s why I would not recommend a not spacered Debon Air or other super high volume shocks on the positive air side.
 

·
Registered
Joined
·
4 Posts
I doubt, that Specialized did this special shock mount to increase stiffness.
This would mean that stress is put on the shock´s shaft on purpose and a company like Specialized pretty much should know what they are doing and why.
Left side is basically (but simplified) the deformation of a fixed shock. Right side is deflection of a shock fixed with a pivoting end. The stress on the shaft will be undoubtedly higher at a fixed end. The stress will be higher at areas with smaller radius at the curves shown here.
A shock should - in my honest opinion - never, never be used as an element to increase stiffness. Just my two cents...
Anyway, the stiffness will be theoretically increased by a fixed moun (I even doubt it is noticeable) but I doubt, that this is, what you actually want: A shock increasing stiffness of your rear frame. The Enduros are already decently stiff anyway...
And yes, just to point it out again: You will very likely void your warranty on your frame, if you use a BikeYoke.

Cheers
 

Attachments

·
Registered
Joined
·
171 Posts
Considering you can get...
Cane creek DB air
Cane Creek Inline
Monarch RT3
Vivid
Ohlins STX
Ohlins TTX
Fox shocks which fit the Standard link, seems a waste of money to me and voids your warranty.
So, where can I get the Fox float X2 for Specialized Enduro? I know it exists, even seen one up for sale on eBay, but can't find any shops who actually sell it.
 
21 - 34 of 34 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top