I took a look at the article and it looks rather impressive. I think I'm a nerd for this stuff. I was taking a look at the charts and see that they're kind of hard to understand for some, so I figured I'd put what I think of them down in writing. TL;DR, the charts show that this bike is designed to pedal extremely well and offer very simple shock tuning and choice for a wide variety of rider weights and styles. Chart 1: Leverage ratio : travel. Basically shows that this has a very linear leverage ratio which is fairly low. Comprehend that however you like, but I see it as making the process of choosing and tuning a shock much simpler. Chart 2: Chainstay lengthening chart is just glorifying how they can take advantage of a rearward axle path (adds a bit more stability on hits and reacts better to square edged bumps), anti-squat (counters pedal bob), yet not suffer from pedal jack, which is a side effect from chainstay lengthening--never a nice feeling to try and crank up a technical section (onto a boulder) then feel part of your cranking motion do nothing (torque resistance inconsistency as the rear suspension goes through its stroke) and have your body fall unexpectedly, causing you to lose balance, traction, and/or smoothness and likely urging you to dismount. Leverage ratio curves can be compensated for with extra shock tuning. Some shocks sometimes don't work for some rider weights--numerous air shocks are notorious for not feeling right under 200+ lb riders, so some bikes are just outright bad for that minority of people, since they can't find a good shock to go with their bike's leverage ratio and not suffer from wallow, sag, and bottom out issues. Having a more linear curve makes it tons easier to spec stuff to suit all sorts of riders and riding styles. It's always a good idea to look at leverage curves to assist in tuning shocks. A number of designs, see curve of 575 and VPP, are designed to be stiff/progressive in the beginning of the stroke (for pedaling efficiency), then plush, then stiff/progressive at the end of the stroke (for bottom out resistance). Basically, the suspension design gives the suspension a certain feel regardless of the shock and such a design works better with shocks with a more linear feel (like a coil) or have the feel enhanced/improved with a shock tuned a certain way. The Yeti's linear ratio is relatively neutral, which basically lets you pick and tune a shock based how you want it to ride without really much thought about how the rear handles it (leverage curve). You'd likely want one with good low speed compression or platform to provide pedaling efficiency and a progressive stroke for bottom out resistance for AM applications. The chainstay lengthing chart is hard to read if you don't conceptualize it (you're forced to, since there's only one scale labeled with graduations). It's not really accurate in a way you can model some computer sim off of it, but basically shows that the rate that the chainstay lengthens is high in the beginning of the stroke (compared to other designs), but then as it goes through its travel, it sharply reduces its rate of chainstay lengthening and the chainstay lengthens much less than other designs at that point of travel. Basically, it's a paper concept trying to "simplify" how the concentric pivot brings the chainstay back in the later part of the stroke. The videos showing the rear suspension going through its stroke probably demonstrates that better. No need to understand the paper... you're better off told basically how that benefits your riding, which is basically is just offering much better pedaling characteristics as well as suspension performance vs certain kinds of obstacles. It's not too helpful just looking at the charts alone; you need to combine them and other aspects (like the shock) to understand how the suspension works as a whole. Basically, the combo of leverage ratio and axle path on the Yeti is unique, which isn't really attained by any well known suspension designs out there. Most of the dual links bikes with this much travel have a more vertical axle path. Some DH bikes purposely go for a rearward axle path (lengthen wheelbase for more high speed stability, allows for a lower BB when sagged, doesn't get hung up on square edged bumps, etc.). Basically, Yeti kind of tuned it to have what they think is a sweet spot for rear suspension. The only thing more I could ask for is adjustability in travel and geo, as far as I'm concerned with rear suspension/frame design, but that would create different leverage curves and such with each setting change (like Ibis limbo chips/Lopes links or different shock hole drillings for travel reduction on other designs). For the uninitiated, this can sound like your suspension design is inferior compared to the Yeti's, but unless you're riding some single pivot that doesn't have a shock rate link between the swingarm and the shock and/or have a shock made by some unknown suspension company that wasn't tuned for the bike, it should perform decently well as a modern FS bike. Like some other modern designs, there can be downsides, such as extra wear on the pivots (dual link bikes like VPP, DW-Link, since there's so much rotation in the pivots), but then that can be overcome by using oversized bearings and pivots to keep them in line with other designs in terms of reliability. This looks like it's another source of creaking, but I'd like to think Yeti addressed that sufficiently. They've been sticking to their "single pivots" for a while now and have been resisting going to more "modern" designs, mainly since their weight and complexity didn't seem worth it, but to have this design change their mind on that policy gets me interested to know how good it is. This is just another step in bike evolution. Just like not everyone hopped on the 29er bandwagon or the DW-Link bandwagon (I'm a fan of ABP myself), this doesn't really change much. Drool worthy for those that like such technical innovation, but anyone with mtn bike passion would just enjoy the ride and being out there despite how advanced their gear is. Just a disclaimer: I'm no expert. I didn't know a damn thing about suspension a few months ago. This write-up basically came from just too much internet surfing. Don't have a college degree or any experience working on suspension. Only looked up how to service my fork just recently, in fact. Additional info I figure I'd throw in: low leverage ratio advantages in general: low shock pressure/spring rates, less stress on shock/frame, better sensitivity... basically, smoother and more durable. Leverage rate is basically how much the wheel moves up and down compared to how much of the shock stroke moves. IE. front wheel moves up 2" fork moves 2" for 1:1 ratio. Rear wheel moves 2.5" and the rear shock moves 1" for 1:2.5 ratio. Most rear shocks have a stroke between 2-3". More info on charts: try to use the color coding to better understand them. Green can sort of be disregarded, once you realize that part of the travel is basically sag. The blue/purple part is the meaty part of the travel. The red is bottom out zone. Example: you can see how VPP sits rather high in its travel at the beginning of the stroke, due to the lower leverage ratio and how the DW-link sits further into its travel when sagged, due to its higher leverage ratio. Not sure how that equates to performance, but I suppose the VPP climbs and pedals faster than the DW-Link bike when climbing smooth stuff if all this suspension knowledge is correct and can actually predict performance. Seems the 575 would have a really wallowy (too plush) mid-stroke, especially under a heavier rider on a XC rear shock like a RP23 due to the high leverage ratio. Another edit: I think writing this out helped *me* understand the charts better, since it basically organized my thoughts better to allow me to easily combine everything to form a better visualization in my head. I think I satisfied my interest and curiosity at this point.
Wow awesome write up varaxis. I understand the design and the charts now. Pretty cool how you can tune your shock now to make it feel how you want
I trust Yeti - they have a long history of successful R and D. No reason it should creak any more than a DW link, Maestro link or VPP link. @Varaxis - thanks for simplifying (?) Wow! I'm still lost. I think I'll just ride one.
Very interesting design... I'd wait to ride one before I make any assumptions based on charts and pics
I really like how Yeti keeps innovating the single pivot design, whether it be through the rail linkage on their DH bikes, or this new eccentric pivot. Looks good.
I must admit, I'm a little late to the party as our shop just got our first SB-66 yesterday, black in size medium. Built it up and have been drooling over it since. Everything about it from design, to paint, to cable routing is just so well executed. Now if only the one I have on backorder would get here sooner! ](*,) Until then, just spreading the Yeti love with some pics
Actually, the Mountain Cycle is just a common single-pivot using the eccentric for the link mount, over-complicating a very primitive design. The SB66 uses the eccentric for the main pivot. Big difference!
met a young dude by the name of Chris this weekend in woods canyon. he had a brand new one in bright yellow. the thing looked the business and he was loving how it was treating him. the build kit was top notch and the kashima fork and shock were blingin'. he had only had it a short time, but i could tell by his style (i followed him and his buddies from bottom of rock-it, through the nature loop and out of the park) that he was an aggressive fast rider, and the SB was doing the trick for him so far. i think these bikes are going to do really well. if i wasnt so in love with my commencal, i would get one of these in a heartbeat.
I wandered into a shop in Santa Monica and saw one of these beast, I'm pretty sure it was employee owned. Yeti has some really good looking bikes throughout their line up. Makes me re-think my Enduro and I just got it all together lol
I want to demo one. I'm in the market for a low and slack AM bike. Can't seem to find any 66 degree 6" travel bikes other than the Enduro EVO. I want a DW bike with that kind of geometry.
I rode one at Interbike, it doesnt ride like a 6 inch AM bike, more like a smaller nimble bike. There are some good reviews from Ibike that say pretty much the same......and the Mojo HD ( DW Link) was better head-to-head by one reviewer. I know its not 66 HA, just throwing that info your way! .
It's pretty obvious by now that "linkless" designs are gonna be the next big thing. that and long travel twenty niners...
I don't think its much more complicated than a regular FS bike. They changed that one pivot to a eccentric cam of sorts. That said, its simplicity is its brilliance. My feeble mind wouldve never thought that you could power movement through the cam via the rear triangles compression. The resistance to bob claimed though may cause a stiff ride in the initial stroke. Much like the Mojo's DW and Treks DRCV thingamajibby's. One can't really tune for all rider weights. I wonder is there are different cams for differently sized riders? Or would it all depend on the air pressure in the shock? edit: the charts just showed up. Seems like the SB-66 has a pretty flat leverage ratio. So it probably ramp up anywhere in the travel, at least according to the charts. as for chain lengthening, the 575 seems to have better numbers. The SB-66 seems to experience chain shortening? What does that do?
I don't understand what they mean by "low" geometry. How is the bike lower than others? Does it have a longer wheelbase? It's a damn fine looking bike.
We had lotsa pedal jack/pedal strikes at Bootleg Canyon, so yeah, I'd say its noticeable low...... and its really long in the top-tube also. .
