RockShox SID Ultimate fork review

RockShox unveiled two new SID forks last year. While many weight-weenies were buzzing about the SID SL Ultimate, which claimed to be the lightest cross-country fork on the market, it was the beefed-up version of the SID that we were most excited about.

In a bid to better handle the demands of modern cross-country riding and racing, RockShox decided to take its regular SID and make it burlier. The new SID is designed for everything from full-XC to lighter trail duties on short-travel, beefed-up XC rigs that many now dub ‘downcountry’ bikes.

RockShox SID Ultimate details

Rather than using 32mm upper tubes (or ‘stanchions’) as is the norm on XC forks – including the lightweight SID SL – the SID moves to larger diameter 35mm stanchions to boost stiffness and steering accuracy. It’s only available to fit 29in wheels and come with one offset, 44mm.

Inside this sturdier chassis sits the new DebonAir spring and lightweight (just 86g) two-position Charger Race Day damper, which control the 120mm of travel (there’s also a 110mm option).

The SID’s new DebonAir spring is designed so that both the positive and negative air chambers are equalised when the fork is fully extended (an update RockShox has since rolled out on its Pike and Lyrik forks).

This and some other tweaks to the air spring are designed to make set up easier and should, according to RockShox, ensure it rides higher in its travel – something older versions of the RockShox suspension fork have been criticised for not doing in the past – but still allows you to use every millimetre available.

The new Charger Race Day damper's weight loss (roughly half the previous Charger 2 RLC) is down to a number of factors, including a reduction in fluid volume and the use of smaller seals, though the brand says the 200-hour service interval remains the same.

Push a bit harder and it's impressive just how well the SID sits into its mid-stroke, never giving up travel too quickly or easily

The new damper features two compression settings (open or fully locked-out) via a fork-top lever or a TwistLoc remote (for an extra £70). Next to this lever is a bleed port should you need to burp bleed the damper quickly.

The rebound adjuster at the base of the leg can be adjusted via a 2.5mm Allen key – that stays popped into the underside of the fork leg – rather than the usual adjuster knob. This helps to shave weight but can also be removed to adjust the rebound damping on the matching SID rear shock (which has no adjuster dial).

Other details include a push-fit brake hose guide, which might require some thumb strength but is far less fiddly to use than the more traditional bolt-on guides. The brake post-mount is designed to allow you to bolt the caliper directly to the fork and works with a 180mm rotor.

There’s more in the way of weight saving, including the use of a Schrader valve cap rather than a wider diameter valve cover. RockShox also includes a small mudguard that can be bolted directly into the two bolt holes located in the rear of the fork arch.

With the mudguard in place, a cut steerer and star-fangled nut inserted, my SID Ultimate weighed 1,610g.

RockShox SID Ultimate performance

Set-up was quick and easy, but using the Allen bolt to alter the rebound damping is a little fiddlier than turning a regular adjuster dial.

With my preferred settings diallied in – I like the fork to rebound quite quickly, and run just enough rebound damping to ensure the fork remains controlled but tracks the trail to the best of its ability – when I pulled up quickly on the bar (lofting the front wheel up as if pulling a manual) I could feel a ‘thunk’ as the fork fully extended.

I’m not talking about a harsh top-out by any means, and when the fork reached its full extension that ‘thunk’ still felt soft, but noticeable. That said, this was really the only time I ever noticed it and it went unnoticed on the trail.

I did some back-to-back testing with a Fox 34 SC (Step Cast) fork and noticed straight away that the SID felt more supple and sensitive throughout the initial part of its stroke, hoovering up smaller bumps and chatter incredibly well, and doing a good job to bolster traction in particularly slippery conditions.

Push a bit harder and it's impressive just how well the SID sits into its mid-stroke too, never giving up travel too quickly or easily, and recovering quickly enough to well match the contours of the trail.

In chunkier terrain, the Fox fork feels a touch calmer and more composed, while the SID is more active. That doesn’t mean to say that the Fox fork is more comfortable, though, because in most situations the SID has the comfort edge. It just seems to work in a more frenetic manner.

On the climbs, reaching and actuating the neatly machined lockout is a doddle should you want to firm the SID up and make things a little more efficient, and leaves the fork feeling rock solid beneath you.

In fact, it's so firm I reserved the lockout for super steep, relatively smooth trail climbs where I was out of the saddle, or for long tarmac drags, simply because I prefer my fork to feel like it’s working, albeit just a small amount, even when riding uphill.

On faster descents where the compressions were coming thick and fast, I appreciated the accuracy and precision from the newly revised chassis. At 68kg, I’m not exactly massive, but considering what this fork is intended for and the travel on tap, I was impressed by how capable the SID was and it made a pleasant change to riding more traditional, skinnier XC-orientated forks that can quickly feel out of their depth.

It’s in those high-speed scenarios when the bumps and compressions come thick and fast that there’s a good chance you’ll notice just how progressive the SID is. Even with no ‘Bottomless Token’ volume spacer fitted inside the air spring (which helps to make it more progressive), I struggled to get the full 120mm of travel on offer.

After seriously heavy hits, I would generally be left with 3 to 5mm of travel. There was only one occasion where I properly bottomed out the fork when I over-shot a decent size jump, landing to flat. Despite this ramp up as you near the fork’s full travel, things never felt harsh or unforgiving, and at no point did my hands feel like they’d been unnecessarily beaten up.

RockShox SID Ultimate bottom line

Overall, the new SID does a fine job handling rougher trails and won’t wince when the bumps start coming thick and fast. There’s enough in terms of stiffness and steering precision to let you push harder on trails that make traditional XC-forks twist and flutter.

It’s easy to forget the SID’s thoroughbred XC heritage at times, where you can easily get carried away when it comes to trail and line choice, and while it might not feel quite as plush or planted as, say, a Pike (RockShox’ outright trail fork), considering it’s weight, I was impressed by just how much it handled.