Thread: Mountain bikes
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Old 10-24-2008, 11:11 AM
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DaveInDenver DaveInDenver is offline
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Originally Posted by wesintl View Post
I don't know why you diss ellsworth. The Truth, in my mind is one of the best suspension bikes ever made. Some frame problems in the past but they work very well. The reason you see some bikes more than others is because there are some rear suspension designs that are WAY better than others.
Ellsworth makes very nice bikes, all US-made, too. My Blur is also a US-made one, but note that in 2008 Santa Cruz shifted production off most their bikes to Taiwan. They had been making some overseas since 2003, but all the VPP frames from 2002 thru 2007 are US-made. Anyway, the only knock against Ellsworth that I've ever heard (this is rumor-ish) is that they can be a little standoffish when dealing with warranty issues. I can speak with authority that Santa Cruz was AWESOME on that front when my Blur frame cracked. Out of warranty by 6 months and they still replaced it for free.

The current crop of designs has been pretty flushed out. There are three main design philosophies. The single pivot, VPP (virtual pivot point) and four bar.

The single point is old but all the experimentation in locating the pivot and more importantly modern platform valved shocks make them viable primarily because of weight and simplicity. They work well and considering there are minimal pivots (as in just one, single isn't just a clever name), they take next to no maintenance. The wheel moves in an arc, which is another issue with a fixed pivot, that's not really what the wheel wants to do. Platform valving is a lock-out inside the shock that detected when there is minimal pedaling going on (i.e., when the shock is barely traveling) and will lock out. Without this the single pivot will tend to inch-worm in granny gear, which is annoying. Some shocks have a manual lock-out and that's fine, but just a PITA.

The four bar is similar to independent front suspension on trucks, well more like suspension on Indy and F1 cars. It's just like it sounds, a simple 4 bar linkage that keeps the suspension active all the time (it's the only style that is not impacted by braking at all). Lots of pivots, that's it's main dink. Also there are patent issues with parts of it that mean either you pay Specialized royalties or you don't sell your bike here in the USA. Scott for one told Specialized to stick it where the sun don't shine and that keeps us from getting the really fancy Scott bikes that they have in Europe. Titus and Ellsworth just pay Specialized for the Horst link, no drama. Oh, Specialized owns that patent, the four bar linkage suspension is what all their FSR frames are based on. The wheel moves linearly up and back, which is pretty much what you want.

The VPP is known by several names, VPP is owned by Santa Cruz and licensed to Intense. Other brands use similar style pivots, like BMC and Giant. It's called something else and the actual design is a little different. But the idea is the same, there are two pivots that act as a single pivot that moves through space. The reason for this is that the pivot point determines leverage ratio and the compromise with a fixed point is that sometimes you want different ratios. Without adjusting shock spring rate, while climbing it is nice if the leverage is a little lower so that the bike does not pogo and going down it is nice if the leverage increase to be more supple. The VPP also uses the energy you introduce through the pedals to fix the pivot point. It's more simple than it sounds, but if you can visualize the pivot point of a single pivot bike moving through an 'S' shape around and behind the bottom bracket that's sort of what's going on. This also means the rear wheel doesn't move in either an arc or a line, it tends to move in and out based on the virtual arm length. Not really an issue in and of itself, but a VPP type bike will have the worst chain slap as the chain stay length changes. Also the frame designer needs to be careful of the cable stop locations to avoid ghost shifting. The first VPP was actual Outland and they were pretty bad about ghost shifting. Outland didn't make it and that's why Santa Cruz ended up with the patent, they bought it from Outland and perfected the design a few years later when FMEA and computer modeling was more sophisticated. Outland had a good idea that they could never get quite right just by experimenting.
I dunno, when the last couple times i've ridden i've went back to my hard tail. If i were going to buy another mtn bike. I'd be going to a Seven custom sola. I'm rapidly loosing touch with the latest since I left my last shop.
Wow, a Seven. Sweet. That for those not familiar is a bike worth more than most of our trucks... Uber sweet bikes.
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