Stumpjumper FSR and Epic get Brain transplant - Bike Magic

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Stumpjumper FSR and Epic get Brain transplant

We’ve already revealed Specialized’s all-new Enduro SL all-mountain weapon. But that’s not all that Spec’ has come up with for 2007 – the Stumpjumper FSR and Epic bikes have had a substantial makeover too, with both featuring Specialized’s own rear shocks.

The Mike McAndrews-designed Brain shock made its first appearance in 2002. It used an inertia valve positioned near to the rear axle to produce an automatic lockout – on smooth trails it was locked out, while bumps caused it to open up. We never really took to the first incarnation – the threshold at which the shock opened up was fixed, it tended to ignore the first bump, deal with the next one and then close again before the third one came along and the transitions from open to closed and back again felt, to put it kindly, a little abrupt.

Development of the Brain has been continuous since then, with lower, and then adjustable thresholds being introduced. For 2007, though, McAndrews has completely redesigned the shock – the higher models in the Epic and FSR range will have the new Specialized Brain shocks, while lower ones retain the Fox Brain.

So what’s different? Most things, in fact. While the new Flow Control Brain does essentially the same thing as the old one, it does it rather differently. Originally the Brain involved a brass weight covering some ports and held down by a spring. An impact at the rear wheel would accelerate the whole mechanism upwards, but the inertia of the brass weight would tend to cause it to get left behind, opening the ports, allowing oil to flow and the suspension to move. The spring would try to push it back closed against the oil, creating a “hydraulic timer” that would see the ports close again a few seconds later. The Brain Fade adjuster dial on later models changed the preload on the spring, altering how hard or easy it was to displace the weight and activate the suspension.

The new Flow Control Brain has numerous changes. For a start, the main part of the shock is arranged the other way around, so that the oil is at the bottom end of the shock and can follow a less circuitous route to the Brain itself, which should quicken its response. And instead of the “hydraulic timer”, the new Brain uses the returning flow of oil during the rebound stroke to close the valve. This means that it closes as soon as its work is done, and also allows the spring under the weight to be a lot lighter (in terms of spring rate, not mass). A lighter spring means faster, smoother reactions. The adjuster dial also does something subtly different – rather than preloading the spring, it controls oil bleed around the inertia circuit. In the words of McAndrews, this “takes the nose off the threshold”. Or to put it another way, it makes the transition between locked and unlocked a lot smoother.

It works, too. We rode Brain-equipped S-Works Stumpjumper FSR and Epic models, and neither displayed any of the unwelcome on/off feel of Brains passim. The shock on the FSR uses a remote Brain linked to the main shock by a hose. Cunningly, you can do an air can service on the shock without having to detach the hose and Brain – the air sleeve will fit over the whole lot. The FSR’s shock doesn’t completely lock out, instead settling to a “Trail Tune” condition that’s firm, but still moves a bit. The new adjuster has a considerable effect, to the extent that with it fully backed off we found the bike actually a bit wallowy and unpleasant. A couple of clicks in seemed to work pretty well, although we can’t say that we’re fully convinced of the benefits of the Brain on middling-travel trail bikes like the FSR. SMind you, after riding the Enduro SL we were wondering a bit about the benefits of the entire Stumpy FSR range, but that’s another story.

The Epic’s Brain is a much more aggressive setup, properly locked out on non-bumpy trails. The more fluid transitions between that state and actually moving and back are instantly noticeable, however. Although in a sense they’re not – what you’re noticing is that you’re not particularly noticing it locking and unlocking. Its not distracting, it doesn’t do anything weird, it starts working off the first bump (rather than the second one) and is generally actually rather good, at least in the context of a short-travel race bike.

Turning to the bikes themselves, the Epic hasn’t seen many changes beyond the shock, although the carbon frame moves a step further down the range and will be found on the Epic Marathon model. The Stumpy FSR has had a considerable makeover. Again, there are carbon frames at the top end, but the M5 aluminium frame on the rest of the range has been revised. It’s smoother looking and lighter, thanks largely to the Super Bridge – an impressive single forging that incorporates the BB shell, main swingarm pivot, bottom part of the seat tube and the struts either side of the shock. The first weld you encounter is between the top of the struts and the bit of the seat tube that the post actually fits in. FSRs will have bearings in the shock mounts across the range, which should put an end to frequent bushing replacements. And there will be women-specific versions of the Stumpjumper FSR and Epic (although not in carbon fibre).

There’ll be no word on pricing and availability until September, so don’t go holding your breath…


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