is the man who powered Yeti into mountain bike's modern era - a highly charged experimental period that produced a number of suspension designs. Yeti's hunger for the ultimate ride spawned a variety of simple single-pivot swingarms, and some out-of-the blue configurations like the 303 downhiller's sliding-track 'Rail Technology
' and more currently, the use of a rolling cam to moderate the rate changes of its longer-travel trail and all-mountain suspension. 'Switch Technology
' is the name that Yeti coined for its new eccentric-cam suspension and Conroy was on hand at Dirt Demo to share some of the back story of the design as well as to walk PB through its most important features.
Owner Chris Conroy poses with Yeti's SB 66 demonstration frame that is used to illustrate the action of its Switch Technology suspension. The eccentric cam (blue) functions as a short link and in combination with the upper rocker, creates a true four-bar suspension system.
Conroy says that Yeti was approached by Sotto Design Group, who showed him a raw prototype of the suspension system. At that time, Yeti's mid-travel ASR 5
was based upon a single-pivot swingarm that drove the shock via a rocker link. Conroy didn't bite the first time because the ASR 5's suspension rate curve was very consistent and he felt that its pedaling was as good as an XC-trailbike gets.
The eccentric cam rides on large, sealed, angular-contact ball bearings. The eccentric and upper rocker link pivots are both machined into a single forging to ensure perfect orientation in the aluminum SB 66 frame.
What changed Conroy's mind, was the fact that Yeti's cross-country suspension, like almost every contemporary design, compromises some degree of mid to end-stroke performance in order to provide firm pedaling in the beginning of the suspension's travel. Short-travel bikes don't suffer as much from this problem, but as travel increases, so does the unwanted rate change. The Switch suspension's eccentric cam had the potential to provide the same degree of firm pedaling action without causing the suspension to push through the mid stroke the first time that the bike hit a substantial bump. Shortly afterwards, when Yeti was developing its six-inch-travel SB 66, they realized that they could use the cam's two-way action to control the shock's leverage rate all the way to full compression.
(From left) The key to the SB 66's smooth suspension action it that the Switch cam rotates counter-clockwise, lengthening the chainstay in the initial part of the suspension travel to provide pedaling firmness. As the swingarm moves into the mid-stroke, the cam reverses direction (far right), creating a smooth-acting linear suspension rate.
Conroy admits that there are a couple of AM/trailbikes out there that may pedal a bit sharper than his SB 66, but that, he explains, is a compromise that Yeti can live with. To maximize pedaling firmness, he explained, one must live with a slightly harsher feel throughout the suspension travel. 'Like us or hate us,' says Conroy. 'Yeti has always made our bikes to showcase handling and suspension performance, even if those attributes may compromise pedaling slightly. In the case of Switch, I think we got both sides of that equation spot on.'
The SB 66 features a replaceable dropout insert that can accommodate 142/12mm through-axles or conventional quick release types. Construction is elegantly executed throughout the chassis.
The SB 66 frame is available in either 26-inch or 29-inch configurations. It has rapidly become Yeti's most popular model. The frame and shock reportedly weigh 7.5 pounds in the aluminum version.
When asked about braking vs suspension action, Conroy shouted out a short, but enthusiastic string of adjectives that probably shouldn't be repeated here, but the gist of it was, 'Switch suspension performs extremely well under braking in any situation.' The fact that Switch suspension is a true four-bar system underscores the possibility of braking being decoupled from the rear suspension, and initial ride impressions bear witness to Conroy's battle cry.
Yeti's SB 66 Carbon is almost two pounds lighter than the aluminum version - and with looks that could kill. The compact nature of Switch rear suspension keeps the bike's stand-over height very low.
A close-up shot of the Switch cam illustrates how compact the system is, with plenty of room for the direct-mount front derailleur and outboard, a narrow profile for feet to clear the swingarm. The main swingarm pivot runs through the eccentric, so torsional forces in the frame are countered by the wide stance of the eccentric bearings and by the rigid upper rocker link.
The fact that Yeti's entire fleet of Demo SB 66 bikes were loaned out throughout the two days of Interbike's Dirt Demo indicates that Yeti did something right. We look forward to an in-depth review of the '66 this fall. In the meantime, visit Yeti's well-organized website
to get the 411 on the geometry and specs of the SB 66.