Is RockShox's new SID fork the Ultimate Race/Trail speed?

RockShox's all-new SID Ultimate pushes XC weight deep into Trail control territory and we love it

RockShox SID Ultimate
(Image: © Guy Kesteven)

BikePerfect Verdict

More grip, more speed, more control, and more adjustment pushes RockShox's benchmark XC/trail fork even further ahead as long as the claimed reliability gains prove true.

Pros

  • +

    Outstandingly supple traction

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    Excellent flat-out/big hit control

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    Noticeably stiffer and slightly lighter

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    Pedal mode is a great ‘efficiency’ addition

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    Should be more reliable long term

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    Significantly cheaper than Fox and Ohlins

Cons

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    No sag markers and low suggested pressures

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    Slight price increase

  • -

    29er, 44mm offset only

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RockShox's latest SID has more control, more adjustability and it’s stiffer, tougher, and lighter. These updates could raise the benchmark on what was already one of the best XC forks available. I have been putting it through its paces to find out how have they done that, what difference does it make on the trail, and whether are there any downsides to watch out for?

RockShox SID Ultimate fork shot

The all new fork gets a new 'Blue Crush' colourway too (Image credit: GuyKesTV)

Design and build

RockShox has given its all-new SID suspension fork a major overhaul for 2023, including the Ultimate, the SID SL superlight fork, and SIDLuxe rear shock. The key things though are that a lighter machined crown now holds longer upper legs sliding through wider spaced bushings. This increases stiffness (think holding a bar/bat/pole with your hands further apart) and there’s a new Maxima Plush Dynamic fluid inside to improve lubrication too. 

Longer upper legs and hollowed-out lower legs allow a 50 percent increase in negative spring volume and 16 percent in positive spring volume. There’s a coil top-out spring and a longer tapered bottom-out elastomer too. The Race Day 2 damper has a new valve head to combat occasional lockout-out failures on previous SID Ultimate forks. RockShox has also added an intermediate ‘Pedal’ mode between ‘Open’ and ‘Lock’ which is engaged with a fork top lever or the TwistLoc Ultimate remote I tested it with. 

You can get the fork in 110 or 120mm travel but only in 29er with a 44mm offset and the minimum rotor size is 180mm. A new ‘Blue Crush’ colorway lets everyone know you’ve got the latest model though (or you can keep it monochrome with a black /white option). 

If you want a lighter fork, SID SL gets a 110mm travel option, with a stiffer machined crown and the same 3P damper changes, and comes in at 170g lighter.

RockShox Charger Race Day 2 damper

New Charger Race Day 2 damper adds an extra 'Pedal' mode between 'Lock' and 'Open'. A new crown is machined for a lighter, stiffer result too (Image credit: GuyKesTV)

Performance 

If you’re worried about longer legs and increased volumes sounding heavier my cut to fit, sample actually saved 8g over the outgoing ’21 SID. There’s still plenty of room around a genuine 2.4in tire (which means masses around the undersized Forekaster here) and an optional rear-facing ‘fender’ in the box too. The new casting uses a push-fit brake hose holder rather than a bolt-in clip and the cable spool for the remote control is easy to thread too. The only thing to be wary of is that the suggested pressures on the leg sticker seem a little low and I ended up running 10 percent more than recommended. That’s harder to assess than normal too as RockShox doesn’t print sag markers on their forks anymore.

Once you’re set up though the new SID Ultimate feels absolutely superb. With the Pedal mode providing a more efficient feel whenever you need it, they’ve clearly opened up the Open mode more. Add the extra negative spring volume and a smoother feel at full extension and the SID now feels more like a coil fork, not an air fork off the top. Butter smooth movement on either side of the sag point means super consistent contact with the ground - a massive advantage for racers prioritizing speed rather than grip with their tire choice. 

RockShox DebonAir+

New DebonAir+ air spring gets more negative volume for glued down traction control (Image credit: GuyKesTV)

If you are picking a more aggressive ‘downcountry’ tire - I did most of the testing with a Maxxis Forecaster up front - then the increased stiffness from the extra leg overlap and wider bushing spacing is obvious too. There’s no sense of tucking, twisting, or binding even when working the Level four-pot brake and 180mm rotor hard into descending turns, just a totally confident, precise, and glued-on feel. It’s no different when slapping down steps, off drops, or ram-raiding random root or rock sections either. Spring and damping are beautifully balanced, silk smooth, and predictably consistent from flutter bumps to full-on slams. As a result, the SID felt more like a 2kg trail fork than a 1.5kg race fork through everything I pointed it at. Together with the SIDLuxe it even pulled a PR out of a dried-out rocky riverbed and rutted singletrack descent on the moors.

If all this sounds a bit too much like Type 1 rather than Type 2 fun then clicking into ‘Pedal’ mode gives a firmer (but still high traction) feel that’ll be more familiar to racers. While the bottom-out elastomer definitely makes it appropriately hard to access the last 15 percent of travel the SID is still generous with its mid-stroke and there’s no external high-speed compression adjustment. Personally, I never found it an issue even pushing hard through berms and other G-out sections but if you want the fork to ride higher then you’ll probably want to add a ‘Bottomless Token’ volume spacer or two. I’d much rather have a super supple fork that can be easily firmed up than a chokey fork that can’t be smoothed out though.

RockShox TwistLoc Ultimate remote control

The three compression modes can be accessed instantly via the new slimmer TwistLoc Ultimate remote control (Image credit: GuyKesTV)

Verdict

SID took a big leap towards trail fork performance at an XC weight in its last generation and the latest version is a brilliant category blurrer. 1500g weight with Pedal and Lockout mode efficiency mean the SID is as start line ready as ever. The extra traction and superbly consistent control definitely align with the fatter tire, slacker geometry direction that racing has been heading in for a while. 

It makes the SID a fantastic choice for trail riders wanting a light, short travel fork that will outclass most trail forks in terms of flat-out, high traction control. Hopefully, the valve head and upper leg / bushing changes will solve previous SID issues too, and I’ll be running this fork long-term and updating this review if anything untoward happens.

Right now though there’s no better aggro race / lightweight trail fork available and it’s a comparative bargain too.

Tech specs: RockShox SID Ultimate

  • Price: $999 / £1069 / €1199 
  • Sizes 44mm offset 29er only
  • Options: 110 or 120mm travel
  • Weight: 1499g
Guy Kesteven
Technical-Editor-at-Large

Guy has been working on Bike Perfect since we launched in 2019. Hatched in Yorkshire he's been hardened by riding round it in all weathers since he was a kid. He spent a few years working in bike shops and warehouses before starting writing and testing for bike mags in 1996. Since then he’s written several million words about several thousand test bikes and a ridiculous amount of riding gear. To make sure he rarely sleeps and to fund his custom tandem habit, he’s also penned a handful of bike-related books and talks to a GoPro for YouTube, too.


Current rides: Cervelo ZFS-5, Forbidden Druid V2, Specialized Chisel, custom Nicolai enduro tandem, Landescape/Swallow custom gravel tandem

Height: 180cm

Weight: 69kg