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First Ride: RockShox Boxxer Ultimate

Aug 3, 2023
by Matt Beer  
RockShox Boxxer Ultimate. Photos Anthony Smith

When RockShox first introduced the Boxxer in 1998 with 150mm of travel we were riding bikes with 26” wheels. As the sport evolved, the amount of travel, stanchion diameter, and wheel sizes all began to grow. In 2018, the Boxxer World Cup became available for a 29” wheel, yet, the 35mm stanchions stuck around. The long and narrow lower legs of the Boxxer looked disproportionate to the huge wheel.

Then, the Zeb arrived with 38mm stanchions in the summer of 2020. Soon after, a Blackbox prototype fork that resembled a dual-crown Zeb started popping up on the World Cup circuit. Nearly two years after spotting the presumed 38mm-stanchion fork on sponsored athletes' bikes, the Boxxer Ultimate entered the ring.

We relayed all of the technical info and availability regarding the Boxxer on July 20th, which you can find here. If you’d like to see a full teardown of the Boxxer, Henry Quinney pinned down RockShox product manager, Jon Cancellier, to show us the internals of the redesigned fork.




RockShox Boxxer Ultimate. Photos Anthony Smith

Setup

Before you even hit the trail, it’s worth pointing out the stanchions are now laser etched with incremental 5mm height markers. That should eliminate setting suboptimal or uneven stanchion heights. The crown bolts continue to display the torque requirements and the compression knobs mimic the rest of the Charger 3 dials with their “middle” position markings.

RockShox developed the TrailHead app to get you started with any fork setup. By punching in the serial number on your fork, travel, and body weight, their algorithm spits out a suggested air pressure number and rebound setting. This will also link you to service kits and further fine-tuning recommendations.

I prefer a firm fork, so when the app started me off at 143 psi, I decided to move up incrementally throughout the day. Every 10 psi is roughly equivalent to what RockShox determines as a spring rate. I was advised to increase air pressure instead of messing about with compression clickers or volume spacers.

From just a parking lot bounce, I increased the pressure to 150 and then 160 psi. That worked well for the abrupt transition from dust to grease. It had been a while since the trails around here received a significant rainstorm and we were in the thick of it.


RockShox Boxxer Ultimate. Photos Anthony Smith

Ride Impressions

RockShox didn’t rush this fork. The design team worked diligently to perfect the air spring, a component of the previous generation fork that was often criticized for being harsh. Senior engineer Tim Lynch described how the design team worked to build the new twin tube air spring to remain consistent through the travel, especially at higher pressures, and that’s the most significant update made to the Boxxer Ultimate.

Acquainting myself with the new air spring felt natural. It’s incredibly supple and consistent. There were no sharp spikes or dead zones. This new fork has all the sensitivity you need, yet you can feel where it stands in the travel.

On the first day, I did look for a touch more stability at the beginning of the stroke and toyed with closing the low-speed compression (LSC) from the middle or starting point. As I became more familiar with the fork and remembered how to relax in the slick conditions, I bumped the fork up to 170 psi.

After two days on the fork, I decided to try it at 180 psi. At 78kg, that wasn’t too firm, but it did start to upset the balance of the bike as the fork stood tall through the corners, even with the LSC back in the middle position. In due time, and in less gritty conditions, I’ll experiment with adding a volume spacer to see how that affects the ramp up. Mechanical bottom outs weren't a concern.

With 25% sag out back, I decided to drop the fork back down to 173 psi and bounced between the rebound at -8 and -9 from closed. Each click at either end of the damper is significant and not as particular to ambient temperatures as some other suspension forks on the market.

Frame, wheel, and tire compliance aside, an additional 200g of structural mass ups your confidence compared to the previous version. The most noticeable change in the chassis stiffness that I noticed from the larger stanchions was the lack of vibration through braking bumps. Widening the crown comes with an increased turning radius too, at least on the Nukeproof Dissent Carbon it was installed on, which arrived with the previous generation Boxxer.

Two days of splashing through puddles at Crankworx (it actually rained this summer) tasked the new fork with supplying grip across the polished roots and muscling through the bomb holes of Whistler’s Garbanzo trails. That’s not enough time to give a full review, although I’ve certainly grown to appreciate the performance of the fully redesigned Boxxer.






Photos: Anthony Smith

Author Info:
mattbeer avatar

Member since Mar 16, 2001
380 articles

92 Comments
  • 124 1
 me as a200+lb 42 year old who rides with his kids "i think i need this new boxxer "
  • 81 0
 your kids: 'we think dad needs this new boxxer'
  • 7 0
 Definitely. Dad's gotta have the latest and greatest right? Kids, you can run with some used handmedowns. Razz
Although I am still sporting the coil boxxer and I do really like the feel of the coil fork.
  • 12 0
 Neighbors Kids: "My dad got in a fight with a boxxer"
  • 5 0
 @twonsarelli: Yes, so they can get the old one Smile
  • 9 0
 I think I need new boxers, but I won't buy them because I think I also need a new boxxer
  • 5 0
 Sell off one kid, and get one!
  • 8 0
 "If my dad gets that new Boxxer, he'll OTB in no time, and I will then inherit said Boxxer, the F-150, and the travel trailer!"
  • 7 0
 College is overrated anyways
  • 4 0
 I can confirm, you definitely need the new boxxer !
  • 43 0
 are there more than 2 types of riders? Type 1- micro adjust, tweak and fiddle with every part on your bike, studying fractions of data and completely interested in the minutiae of every component and angle, understanding Boost, tokens, fork psi etc etc... Type 2- slap it on your bike and never touch it until it breaks.
  • 128 1
 Type 2.5: Insist on getting the gold-ultra-adjustable version of stuff, swearing to get things dialed 'this time', and then slap it on bike and never touch it, and rely on type 1 friends to fiddle on my behalf.
  • 36 0
 @jake28: damn this hits wayyy too close to home
  • 21 0
 @jake28: don't forget 'rely on current or former mechanic friend who will work for alcohol'
  • 10 0
 @jake28: Entire pinkbike user base just catching strays here
  • 4 0
 usually the more adjustments there are, the less people are going to use them but still rave about how everything is adjustable.
  • 4 0
 If it works it works. Ive been slapping forks on bikes for years and not really adjusting much. Just dont ask about my forks service history.
  • 3 0
 @jake28: 2.5.1: get the highest level of shock/fork, set up right at the recommended settings, fiddle for 1.5 rides, then settle on a spot your brain can adjust to over the next 5 rides.....never ever touch it again.
  • 4 0
 @jake28: Oof, over here watching my buddy compressing the front end of my bike and telling me to let off about 10 PSI while my compression and rebound are still set to factory.
  • 1 1
 Type Best: get all the adjustments, fiddle once or twice in the beginning, get it dialed way better than any unadjustable fork could ever be unless your size and bike and riding fit exactly into the center of SRAM's bell curve, never touch it again.
  • 1 0
 @zedpm: always start with spring rate
  • 1 0
 @tgr9: usually the less adjustments there are, the less people are able to set them up, but still rave about how everything is "set & forget" (except they didn't set anything, just forgot that part).
  • 2 0
 @justinfoil: so not set&forget, but forget&forget? lol
  • 36 0
 That red on red Nukeproof is beautiful
  • 2 0
 Plus red grips, seat, and wheel accents.
  • 1 0
 Beautiful yet redundant
  • 12 0
 Is my shock pump wrong, or is 173 psi super high?
  • 6 0
 It greatly depends on the fork, rider weight, riding style, etc. For some, 173 is way too much, for others it might not be enough. It'll be different for everyone.
  • 5 1
 got a mere 55psi in my ‘23 190mm Zeb Ult at 190lbs!
  • 6 1
 @rookie100: dh forks and single crown typically require very different amounts of pressure. 55 psi in a dh fork would be at like 50% sag.
  • 10 0
 @Lando406: completely different air springs between the Boxxer and Zeb.
  • 1 0
 @rookie100: yeah that zeb runs so low in required pressure. I run a 160 zeb at like 57 psi with room to drop at 180 lbs.
  • 3 0
 The twin tube shock thing is a really low volume shock (narrow) so needs high pressures to provide the same amount of support. Effectively you need the same amount of air to hold your bodyweight at, say 50mm sag, so if the air chamber is narrower that air is shoved into a smaller space increasing the pressure
  • 1 0
 Just to add to that, the reason zebs have less pressure than, say lyriks is because the air spring is 38mm wide not 35mm wide, so the volume is larger. If they all ran twintube shocks of the same diameter they'd all need similar pressure
  • 2 0
 @hughlunnon: Forks that have a bigger negative chamber also need more pressure to obtain the same springrate.
  • 2 0
 @hughlunnon: it's not the volume, it's the piston area. This volume might be higher than a Zeb since it's longer, but the piston is so much smaller: less Square Inches means more Pressure to get the same forces.

Given the same size piston, a smaller volumes air spring would need less pressure to get the same sag (and bottom-out force), since the pressure will increase faster because the relative volume shrinks faster.

It's also not a twin-tube anything. The air-spring uses one tube, it just happens to be inside another tube (that is not part of the spring).
  • 10 1
 find it confusing how many people say 38s and Zeb are far stiffer than most riders need and in the same breath bang on about the advantages of the stiffness of doublecrown forks
  • 13 6
 Um because one is on a trail bike and one is on a DH bike??
  • 17 1
 I think riders just drank the Kool-Aid. They ramble about stanchion diameter without even concidering the stiffness of the crown and lowers or the stanchions wall thickness.

Its like kids talking about cars and which one has the most horepower.

Furthermore, for every world cup pro on a "noodly" Boxxer or "flexy" Lyrik/36, there are 1000 Amateurs claiming they are not stiff enough for them. This part isnt really an argument, just an interesting discrepancy.
  • 6 0
 I mean to be honest, most riders don't need them. Many of us (myself sometimes included) like to forget that pros and even some local legends were going faaaaar bigger and faster on 36mm stanchion forks than we normies ever will. But, new parts are fun, and "f*ck off, I like upgrading my bike" is a fine argument. It's all individual
  • 2 1
 @endoplasmicreticulum: pros ride what the boss man says, not what they like. can't ride competitors fork, can you?
  • 1 0
 Different types slash directions of stiffness. Dual-crowns have awesome torsional stiffness: the axle stays parallel to the bars. Single a single crown, much of that is solely on the steerer, and they're stupidly skinny at the top. The other flex, that is often claimed to be to much, is lateral: fore-aft and side-to-side, and they're both mostly controlled by the stanchions (bigger tubes are stiffer for a given weight). Fore-aft stiffness is usually good, but some people like to set up their spring super firm so it "feels fast", then rely on the fore-aft flex to add some give to the system. Side-to-side stiffness is also usually good, but some people think it makes them ping-pong through chundery stuff. But any lateral chassis flex shifts the movement control away from the tunable damper and into the untuneable structure, while also often putting undesirable loads on the damper and spring. Stiffness in suspension parts is almost always good, and if you think you need a softer chassis, you probably just need better dampers.
  • 3 0
 Or they don't realize it's actually the air spring or damper that's the culprit. Not the chassis
  • 1 0
 @SillyTadpole: Hell yea, dude!
  • 9 0
 “ Every 10 psi is roughly equivalent to what RockShox determines as a spring rate.”

I’m confused, what does that mean?
  • 35 0
 150psi is a spring rate. and 160psi is a spring rate. 170psi is also a spring rate. and 180psi is indeed also a spring rate But 169psi, that is not a spring rate. and 177.4psi, also not a spring rate. Get with the program
  • 3 0
 @jdkellogg: what about 190 and 199,2?
  • 1 0
 Yes very unclear
  • 4 0
 Think of coil springs, they come in designated spring rates, usually in 50 pound increments in the MTB world. 350, 400, 450 etc... Rockshox is saying that each 10 psi translates to increasing or decreasing one spring rate, which is just enough to noticeably change the characteristics of the spring stiffness.
  • 1 0
 @jackfunk: ah gottcha. Cheers
  • 2 0
 @jdkellogg: 169 is definitely a very noice rate. Springing all night long.
  • 8 0
 "This will make me a better rider..."
  • 6 0
 Sram upgrades release planning :
*6 months : bigger negative chamber
*1 year : new charger damper
*1.5 year : new airspring because the negative chamber is too big
  • 3 0
 You forgot "new air spring (which is not an upgrade) because people don't understand pneumatic top-out and think they're getting robbed of travel"
  • 2 1
 "Every 10 psi is roughly equivalent to what RockShox determines as a spring rate."

What? Is this supposed to mean each coil rate option (for some other fork?) is close to a 10 psi change in this air spring? What coils? And who cares? One of the best things about air is that you're not locked into set coil rates.
  • 1 0
 It's not a twin-tube spring, it's just tube in another tube. The outside tube doesn't contribute to the main air spring. In fact, in contributes even less because the air volume outside the main spring is now much bigger, reducing the "casting ram". That outer air volume is also not connected at all to the adjustable pressure of the main spring, and is indeed not adjustable at all (beyond changing bath oil volume, which I'm sure SRAM would tell you not to do ever). Tube in another tube.
  • 4 2
 Why would widening the crowns change the turning radius? The wheel angle is going to change identically relative to the handlebar angle, regardless of the crown width, right?
  • 2 0
 Might the wider stanchions cause the fork to come into contact with the bump stops earlier?
  • 3 0
 Max turning radius is improved, the amount the wheel moves per mil of bar movement is the same
  • 2 0
 Think tight switchback where you are turning the bars to the limit, the older Boxxer would stop before the new one or a Fox 40.
  • 3 2
 @mattbeer I think you mean decrease the turning radius. You can turn tighter right?
Smaller diameter = smaller circles.
  • 5 5
 @mattbeer - can you speak to the rebound dampening? I and many others have been unable to get the ZEB fast enough for our liking.
  • 1 0
 Which zeb are you on? I have the 2.1 one and I can definitely make it fast enough.
  • 5 0
 Wild, I can't get mine slow enough for my liking.
  • 4 4
 @marlon-d: slow enough? Wild. Press x to doubt
  • 3 0
 @wolftwenty1 That could depend on what pressure you have the air spring set to and what you consider to be "fast". I weigh 78 kg and ran 173 PSI. The rebound was 8-9 clicks from closed, which aligns with the TrailHead app suggestion at that pressure.
  • 4 0
 @bigmeatpete420: newest one with buttercups. SRAM guys had me reduce pressure and add a token..still wide open though. Said they get that feedback a lot actually. *dunno*

Also, lol at the downvotes. This place..lol
  • 1 0
 @wolftwenty1: what pressure do you run? I think I’m about mid 80s I want to say?
  • 1 0
 @wolftwenty1: I run 55psi and 3 tokens in mine, so that may be a factor in mine being too quick.
  • 1 0
 @wolftwenty1: wish I could help
You more. Maybe a retune will get you where you want. I would contact a local tuner and see what they say
  • 2 0
 @bigmeatpete420: Took it to the SRAM guys and they were cool and its better for sure. Only have 2 rides on it since so we will see. But as noted, they said they are getting that feedback a lot on the new ones.
  • 1 0
 @wolftwenty1: whut? reducing pressure could only make rebound even slower. i take it your best solution is taking it apart and removing shims from rebound piston. i've a dorado with too stiff a stack, too fast at low speed rebound, too slow and ground hugging at high speed, drags the front end down off small kickers. the only way to "fix" it is giving it to someone twice my weight, and therefore spring pressure
  • 1 0
 @baca262: actually if you reduce pressure slightly and add a token you’ll get a slightly stiffer spring in the later bit of the travel making the rebound feel faster so this actually is good advice. They probably meant like put one token in and go from 55 to 54. But yes, you are right the only way to remedy this is to change the rebound stack. You might be able to get some results with using a center wait oil but I don’t think that’s a good idea.
  • 2 0
 He's pretty damp in those photos
  • 1 0
 @bigmeatpete420: more progressive spring would only rebound faster in the near bottom out area, everywhere else it would be slower. it's the beginning and mid travel that'll give slow feeling, anything shimmed rebounds fast near the end of travel
  • 1 1
 First time I've ever heard of someone having to put in more air than what Rockshox recommends. I always find they recommend way too much pressure.
  • 3 3
 I usually go higher in pressure than RS recommends, but I also like stiffer bikes generally (I ride like a jackass)
  • 2 0
 Indicates that the damper is way too soft, forcing the rider to compensate with a higher spring rate to get the needed support. Not unusual for Rockshox forks since forever.
  • 2 1
 Would be interessting how much difference there is compared to the zebb.
  • 6 0
 Your comparing apples to chestnuts right there.
  • 1 0
 @hhaaiirryy: would you say that if it was the old 66 vs 888?
  • 1 0
 I suspect there will be a new Red Zeb with the dual air chamber and holes in the stanchions soon enough...
  • 2 1
 little off subject but how is the nukeproof DH bike.
  • 1 0
 @drjohn: literally a different bike mate
  • 1 0
 Bummer the new Nukeproof Dissent won't be coming with the new Boxxer.
  • 1 0
 Damned with faint praise.
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