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RockShox SID Ultimate Fork

Vital Rating: (Excellent)
RockShox SID Ultimate - Signature Blue with Fender
 RockShox SID Ultimate Fork  RockShox SID Ultimate Fork  RockShox SID Ultimate Fork
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We Ride the All-New RockShox SID Ultimate

The all-new and very blue 2021 RockShox SID is a featherweight fighter that goes round for round with the welterweights.

Rating: Vital Review
We Ride the All-New RockShox SID Ultimate

For the first time ever, the RockShox SID goes to a 35mm stanchion with the introduction of the 120mm SID Ultimate and SID Select. The jump to a 35mm stanchion is a seemingly natural progression for the fork, considering the capability of even the fastest XC and light trail bikes these days. Vital took receipt of a RockShox SID Ultimate and have logged a few miles as well as dug into the guts of this new cross country fork to see what makes it tick and who may benefit most from this new technology.


2021 RockShox SID Ultimate Highlights

  • Ultra-slim and trim, entirely new chassis
  • All-new Charger Race Day damper (94g)
  • Updated DebonAir spring
  • 35mm stanchions
  • Travel: 120mm travel only
  • Wheel Size: 29” only
  • Offset: 44mm only
  • Weight: 1,537g (3.4-pounds)
  • Twist-lock remote option available
  • Integrated bolt-on fender
  • New SKF Seals
  • Ultimate High Gloss Black and Signature SID Blue colors
  • MSRP: $899-$969 USD
  • Available March 2020

A New Body

The SID has always been at the forefront of lightweight suspension forks. Through a complete chassis overhaul and the all-new Charger Race Day Damper, the SID still manages to pull ahead by a handful of paperclips when compared to FOX’s Step-Cast 34. Tipping scales at just 94g, the Charger Race Day damper makes a Sharpie think about going on a diet.

Unlike previous models of the SID, RockShox has gone away from using the full carbon crown and steerer tube which they say allowed for more time to focus on development in other areas, as well as maintain desirable stiffness, while still shaving a couple of grams.

With the introduction of the 35mm SID lineup, RockShox has also re-formulated the DebonAir spring for a more purpose-built positive and negative air spring ratio. The update to DebonAir for SID models improves overall ride height with an XC focus.


Zip-tied fenders as an afterthought are ending up on the majority of bikes these days. RockShox set aside some time in between shaving every possible gram from the new fork crown and lower legs, to integrate a well-designed, removable fender. The fender mounts to a couple of bolts on the back of the lower leg bridge and offers some sweet relief from the mud-slingin’ front tire.

New Charger Race Day Damper

There is no denying that the new Charger Race Day damper that comes stock in the all-new SID Ultimate is slim, trim, and ultra-light. Weighing in at 94g, this is the lightest cartridge style damper on the market.

As thin as a Sharpie. Every extra gram has been taken out of the damper.

Similar to the rest of the Charger damper family, the Race Day damper uses a bladder to capture the oil as it is displaced by the damper shaft during an impact. The bladder design also acts as a small negative spring to return the damping oil as the fork returns to full travel. The damper only contains a total of about 16 or 17cc’s of Maxima Plush oil.

The rebound piston head is a two-port design that uses shims to control the damping. Unlike the current Charger 2 or 2.1 damper from RockShox, the base valve is made up of quite a few very small ports vs. the needle design of Charger 2 and 2.1. RockShox has designed a very simple, and effective lockout that closes these ports when the lever is flipped or the remote is engaged. Even with the shaft only displacing about 5cc’s of Plush oil, the lockout is very firm. Aside from the on-off lockout switch, there are not any other compression adjustments.


With the lighter weight and the firm lockout at the forefront of the design, the Charger Race Day damper is definitely an intriguing piece of modern engineering.

DebonAir Spring Updates

Along with all the updates coming with the new SID Ultimate, RockShox has also re-formulated their current DebonAir spring to have more of an XC focus. By slightly decreasing the negative air volume, RockShox was able to achieve taller ride height from the air spring. This will ultimately give riders more support and make better use of the limited amount of travel.



Initial Ride Impressions

Out of the box, the SID Ultimate was pleasantly lightweight. Installation on our XXL Santa Cruz Tallboy was incredibly easy. In fact, to achieve the desired stack height, we didn’t even have to cut the steerer tube. After a quick star nut install, we bolted on the brake caliper, snapped the brake line into the hose guide, and were ready to roll.


For the initial setup, we chose to leave everything stock. The fork came with zero tokens installed so it was a matter of setting air pressure to the recommended PSI for rider weight and adjusting the rebound to a good starting point.

On the trail, the first thing that immediately jumped out about the SID Ultimate was the weight. The front end of the bike was noticeably easier to maneuver, and hey, no complaints on fewer grams for climbing. Having ridden many 32mm and even 28mm forks in the past, the 35mm stanchions of the SID were a refreshing change of pace in terms of stiffness for the short travel fork world. The added stiffness definitely gave the fork a level up in terms of on-trail capability, and we felt comfortable dropping into some of the steeper, chunkier lines in the Durango area.


On the climbs, we flipped the lockout switch a handful of times and were definitely impressed by the firmness of the lockout. In a dead sprint to the line, even under a larger rider, the lockout on the Charger Race Day damper definitely felt like it would have an advantage.

As XC race bikes become more capable, World Cup XC racing gets gnarlier, and top athletes jump on board with more capable suspension, there is no doubt that we’ll see this 35mm fork enter the top of the XC racing arena.

In the first few rides, we went back and forth a bit on air pressures from the upper end of recommended air pressure for our rider weight and even into the next weight range below, trying to find a balance between initial suppleness and support. In order to get a proper amount of support and keep the fork riding higher in the travel, we were sacrificing traction and suppleness. Eventually, we opted to install the two tokens that came with the fork. With these tokens installed, we were able to get closer to the air pressure that gave the best suppleness, while gaining more support or ride height in the mid-stroke.


With the spring side dialed in, it was time to dive into fine-tuning the rebound. We found that, especially with the tokens installed, we were having some trouble with the fork not feeling very controlled in successive bigger, hard hits. If we slowed the rebound down a click or two, we would lose some of the playfulness and poppiness of the front end. Ultimately, we settled at 4-clicks from fully closed, but at 180-pounds, it still felt like we weren't quite getting everything desired from the rebound circuit.


On the compression side of things, the Race Day damper felt nice and smooth. When compared to the initial feel of the 32mm Charger 2 and Charger 2.1 dampers, the Race Day damper had a similar feel, if not a slight improvement, allowing us to run a touch more air pressure and still maintain some suppleness from the initial stroke.

With the tokens installed and 85psi in the fork, the SID Ultimate definitely held its own on some of the most technical and demanding XC trails in the Durango area. Aside from struggling a bit with the rebound adjustability, the fork proved plenty stiff and is definitely ready for some of the gnarlier XC trails.

Also New from RockShox

Obviously this wouldn’t be a new SID feature unless RockShox had something for the calorie counting XC hammerheads. Along with the 35mm SID Ultimate, RockShox is taking all the weight shaving updates and applying them to a 32mm stanchion version, the SID SL. The SID SL Ultimate also gets its own version of the Charger Race Day damper that tips the scales at 89g. The fork features a similar look and feel as the 35mm version but with 32mm stanchions, narrow stance, and 100mm of travel; the SID SL shaves even more paper clips to keep the die-hard XC racer chasing the top step of the box. One notable update to the 32mm SID SL is the introduction of an SKF wiper seal, which should be a big improvement to reduce friction and keep out dust.


For the model year 2021, RockShox is also re-introducing the SID rear shock that lived and died in the early 2000s. SID Luxe Ultimate is a super lightweight (yep, you guessed it), xc focused rear shock. Stylistically, the SID Luxe rear shock has a similar machined, ultra trim look featured on the new SID and SID SL for a complete package.


The Charger Race Day damper is backward compatible and will be available as an aftermarket upgrade for all 32mm 100-120mm SID and Reba forks back to the model-year 2014. The SID SL, SID Luxe, and Charger Race Day 32mm damper upgrades will be available aftermarket March 2020.

For more information on compatibility and product availability, visit

What's The Bottom Line?

The new RockShox SID Ultimate takes a little influence from its bigger brothers and packs a lot of punch into a lightweight 35mm package. Between the all-new chassis with an integrated fender, super minimal Charger Race Day damper, and the updated DebonAir spring; the SID Ultimate is an exciting addition to the RockShox lineup. As XC race bikes become more capable, World Cup XC racing gets gnarlier, and top athletes jump on board with more capable suspension, there is no doubt that we’ll see this 35mm fork enter the top of the XC racing arena.

As for light trail or “down-country” oriented applications, the SID Ultimate fills a very niche market as a super-light 120mm, 29er only fork. For some applications and riding styles, the SID Ultimate has its limitations. Larger riders may struggle with dialing in the rebound, but the lighter compression tune and more balanced DebonAir spring help keep the fork more supple and supportive.

Vital MTB First Ride Rating: 4 stars - Excellent


About The Reviewer

Dylan Stucki - Age: 31 // Years Riding: 20 // Height: 6'5" (1.96m) // Weight: 180-pounds (81.6kg)

When he's not busy ripping the Colorado high country singletrack with friends, you're likely to find Dylan battling it out on the enduro race circuit. Since he's a big guy and charges hard, he breaks a lot of stuff. With a broad riding and racing history, he's naturally a perceptive and particular rider who picks up on the subtleties.


Product RockShox SID Ultimate Fork
Riding Type Cross Country, Trail
Wheel Size 29"
Travel 120mm
Spring Type 2021 DebonAir air spring
Damping 2021 Charger Race Day Damper
External Adjustments 2-position compression (open and lock)
Low-speed rebound compression
Available with TwistLoc remote option
Crown Single
Front Axle 15mm x 110mm (Boost)
Brake Mounts Post mount
Steer Tube Diameter Tapered
Steer Tube Construction Machined/anodized aluminum
Stanchion Diameter 35mm tapered wall aluminum
Colors Signature SID Blue and Ultimate High Gloss Black with foil graphics
Weight 3 lb 6.2 oz (1,537 g)
Miscellaneous 2021 model year
Short fender compatible (includes RockShox branded 2-bolt short fender)
Offset: 44mm
Sag: 15-25%
  • $899
  • $969
More Info


  • An entirely new 35mm chassis for 2021 optimized to be stiff and eliminate as much weight as possible
  • 2021 Charger Race Day Damper – RockShox's lightest production damper with rock-solid lockout to date
  • 2021 DebonAir air spring – tuned specifically to meet the demands of XC and maintains a higher ride height for increased confidence and control
  • 2021 Ultra-low friction SKF wiper seals – provide long-lasting fork performance and improve overall suspension feel
  • Maxima Plush damping fluid – reduces friction and silences damper noise

For more info, visit the RockShox website.

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