It’s ten years since RockShox launched the first fork to bear the SID name. Since then it’s been the most successful XC race fork out there, and has pretty much become the default setting for those in the market for something short travel and lightweight.

SID stands for Superlight Integrated Design, and most SIDs over the years have focused on light weight as a priority (ignoring such statistical outliers as the SID XL dual-crown fork). Inevitably this has lead to compromise elsewhere, and it’s fair to say that the current SID isn’t known as one of the stiffest forks around.
For 2008, though, there’s an all-new SID and something of a philosophical shift. The designers have reasoned that it’s better to have a little bit more weight in the interests of improved fork performance – lower legs tend not to like to slide smoothly over non-parallel stanchions. The thinking is that low weight only helps on climbs, but decent suspension helps anywhere there are bumps.

To that end, RockShox’s goal was to make a fork with comparable (or better) stiffness to the well-regarded Reba World Cup with a target weight of 1,450g (3.2lb) – not the lightest fork out there, but you only have to look at the new SID to realise that it’s a pretty stout offering.

Stanchions are 32mm diameter, considerably bigger than the current SID. To save some weight after going to bigger tubes, everything is shorter. The bottom sections of the lower legs are hollow – the bolts holding them on to the plunger rods are somewhere roughly level with the top caliper mount. That means shorter (and hence lighter) internals, less oil and shorter stanchions.

Following the lead of RockShox’s big-hitting Lyric and Totem forks, the new SID features “Power Bulges” on the lower legs. The idea here is to get more material around the interfaces between stanchions and sliders. On the lower-line SID models the Power Bulges will be magnesium and will stick out, Lyric-style. On the posh World Cup model, though, the raw casting will have the bulges machined off, shallow recesses machined out and then filled with carbon fibre to achieve the same result at lower weight. The WC will perform the same trick to beef up the upper bushing area and fork brace.

Inside it’s a familiar RockShox story, but with a twist. The new SID uses a Dual Air/Motion Control spring/damper setup but with a couple of tweaks. It’s got “dual flow” rebound damping, which means that the rebound you get over small bumps isn’t the same as that which you get over big hits. The idea is to make it easier to set the fork up rather than having to strike a happy medium between not kicking back on the big bumps and not packing down on the pattery stuff. The World Cup SID also has dual flow compression damping. The usual nylon Motion Control spring tube has been replaced by a machined titanium one. This saves some space, thus making room for a shim stack for high-speed compression damping.

Eagle-eyed weight freaks will notice the absence of a carbon fibre crown/steerer combination. The RockShox engineers felt that good old aluminium was the way to go – carbon works best when you can use a lot of it, and the volume of a crown/steerer is obviously constrained. Using alloy let them make a lower-profile crown and not worry about stress risers at the crown/steerer junction. There’s certainly no denying that alloy steerers are a whole lot more user-friendly than carbon ones – easier to cut, you can just bang a star-fangled nut in there to make the headset work and you don’t have to worry quite so much about stem clamp damage.

There’ll be three levels of SID – World Cup, Team and Race – each available in 80 or 100mm travel versions. The new forks are expected to be on sale in February 2008 – pricing is still up in the air but we’d imagine that it’d be not too far off current SID prices.