Stickers only go so far in covering up a pre-production fork. We’ve seen the BlackBox (RockShox’s prototype components) decals covering the sturdy-looking fork for nearly two seasons, but the official debut of the Boxxer Ultimate is here.
The Boxxer is entirely redesigned from the previous iteration. The most apparent change is the move from 35 to 38mm stanchions. A burlier chassis also takes features like the Charger 3 RC2 damper and ButterCups that were implemented on the Zeb, Lyrik, and Pike single crown forks a year ago, however, there is more at play inside the larger tubes than you may expect. In particular, the DebonAir+ air spring required clever engineering to work around the new stanchion size.
Boxxer Ultimate Details • Travel options: 180, 190, 200 mm
• Redesigned 38mm stanchion chassis
• Fork offset: 44mm (27.5”), 48mm (27.5”, 29”) 52mm (29”)
• Charger 3 RC2 damper w/ high-speed compression, low-speed compression, and rebound
• DebonAir+ twin tube air spring with optimized air volume
• ButterCups on air and damper shafts
• Lubricating ports at end of stanchions
• Gloss Black or Signature Electric Red colors
• Boxxer 4-bolt fender incl. (aftermarket only)
• Weight: 2,840g (200mm travel, 48mm offset)
• MSRP: $1,899 USD, € 2,279 EUR*, £2,029 GBR* (*incl. VAT)
•
rockshox.com
ChassisLet’s start with the obvious first - 38mm stanchions. Riders have expressed their concerns with oversized tubes being overly stiff. RockShox says that they kept their eye on this when designing the new chassis and took careful consideration to not make this Boxxer brutally stiff.
At the bottom of the upper tubes, holes have been drilled to promote oil circulation as the fork moves through its travel. Upon bottom out, these ports are said to help evenly distribute the oil and reduce inconsistencies in the spring rate. SKF wiper seals and Maxima Plush Dynamic Suspension Lube take care of friction and keep the tubes sliding smoothly.
Laser etched on each stanchion are gradients to measure the effective axle to crown length at a glance. Another nice touch is the continued marking of the required torque of each bolt, including the Maxle DH.
The crowns see lots of material milled away and come in three offsets: 44, 48, and 52mm. The shortest and longest correspond to 27.5 and 29” front wheels, whereas the middle ground offset of 48mm is acceptable for either wheel size.
There’s also a new 4-bolt fender to come (included with aftermarket fork purchase) that will cover more area in front of and behind the arch than the Zeb’s short mud flap.
Compared to the previous chassis, there is a weight penalty of nearly 200g. All of those features inside the new architecture should come with performance benefits.
DebonAir+ Twin Tube Air SpringRockShox worked tirelessly to perfect the air spring on the new Boxxer. Moving to a larger diameter stanchion posed challenges to limiting the progressivity of the air spring as it moved through the 200mm of travel. The solution? A twin tube DebonAir+ air spring.
In the new fork a separate air chamber rides inside the 38mm stanchion and the traditional air spring was altered from 10mm to a hollow 14mm to allow for extra negative air volume. This makes the DebonAir+ twin tube RockShox’s most linear air spring yet. There’s also a revised bottom-out bumper, for those wincing impacts.
ButterCups are also at play in the Boxxer Ultimate and account for 10mm of the travel. Both the damper and air spring rods sit on the rubber elastomers to reduce high bump frequencies from trail chatter.
Charger 3 RC2 DamperTransitioning from their longer-travel single crown forks, RockShox has implemented the Charger 3 into the Boxxer Ultimate with high and low-speed compression, and rebound adjustments. RockShox touts the fact of eliminating “cross-talk” between the two compression adjustments. What that means is that you can now independently adjust one without affecting the other for straightforward tuning. The suspension fluid from Maxima is also designed to be silent as it circulates through the damper.
Boxxer and UpgradesAvailable on complete bikes only, a simpler Boxxer will also meet a certain price point for some customers. This fork will only have one compression adjuster and exclude the ButterCups, although the chassis remains the same and both the damper and spring can be retrofitted.
Boxxer Details
• Travel options: 180, 190, 200 mm
• Redesigned 38mm stanchion chassis
• Fork offset: 44mm (27.5”), 48mm (27.5”, 29”) 52mm (29”)
• Charger 3 RC damper w/ compression and rebound
• DebonAir+ twin tube air spring with optimized air volume
• Lubricating ports at end of stanchions
• BoXXer 4-bolt fender avail.
• Weight: 2,680g (200mm travel, 48mm offset)
• MSRP: N/A (OEM only)
Charger RC3 Damper Upgrade
• Adjustments: high-speed compression, low-speed compression, and rebound
• ButterCups
• MSRP: $358 USD, €399 EUR*, £356 GBR*, *Includes VAT
DebonAir+ Air Spring Upgrade
• DebonAir+ twin tube air spring with ButterCups
• MSRP: $104 USD, €113 EUR*, £101 GBR*, *Includes VAT
It will 100% not work.
You mean for the people?
Because I’m all about SRAM, but they can lose the plot the blink of an eye. Make a great product worse..
It took me years to find a g-out that sent my bike into the high speed compression circuit consistently.
Here’s a great video from Vorsprung about the difference between low and high speed circuits.
www.youtube.com/watch?v=JEBNlHXUGdE&t=737s
Try running your ++ chamber closer in pressure to the + chamber. (Not 50% more, like 10-20% more than the +)
And so 70psi in top, 77 in bottom. Etc
You should be able to set it up so its really supple at the top, yet supportive through the mid, and hardly ever/never bottom out because of the HBO.
On the rear shock you have to undo 2/3 bolts to get the shock off, then unscrew the spring backplate (can't remember its name), slide the spring off, and then reverse the procedure.
Probably 10 mins for each end, no?
what is different is that the rear shock has a lot more leverage over the seals (you're typically running a 4:1 ratio through the linkage, whereas the fork is 1:1), but I'm not sure why that would encourage the use of a air can (if anything the other way round). perhaps its simply weight?
That all being said, it seems like there are negatives to both setups (coil reacts consistently, but limited spring rates. Airsprings are much more fine tuneable, but can change slightly with heat and what not).
More room for damping tech?
My original comment was alluding to the overall tone of this article, which to me reads like: "Hey! Boxxers are now 38mm, even though it's heavier and we had to do a bunch of engineering to make it work..." without explaining any actual benefits.
I'm sure there may be some benefits to 38mm besides "MOAR GIRTH MARKETING," but all I see is the planned obsolescence of 35mm Boxxers (no backwards compatibility w/ new air springs, dampers, different offset crowns, etc).
Also...RS has always had different offset crown options for Boxxers. I have the +0 crown, which gives 46mm offset for 29r (feels great on the park bike) and 36mm offset for 650b.
Old ones were 35mm which aligned with Lyriks, so obvious manufacturing synergies there and why they chose 35mm. What I'm saying is, this article does not give a REAL reason for going 38mm (and leaving 35mm behind).
I know I'll eventually have to get a new fork (hope they keep supporting 35mm boxxers for a while so I don't have to). Just a bummer when the "new architecture" doesn't seem to have any obvious benefits over the "old architecture."
Obviously there are manufacturing efficiencies with commonality between Zebs and Boxxers now...so I guess they might as well (even though they still sell 35mm Lyriks).
The old Boxxers still work same as they ever have, and RS will continue to provide maintenance parts for a while, which means they're not even obsolete at all, let alone "planned from the start to be obsolete".
p.vitalmtb.com/photos/users/44569/photos/133106/s1600_IMG_3544.jpg?VersionId=lfhgR45MfmS2sdqErjDcZBp9A_p6w9MQ
Running one at 180mm on my newer Transition Patrol alloy (with +0 offset crown for 46mm offset on 29r). Without a shit ton of spacers, it's way too linear for me (I think I have 4 or 5 in there now), plenty of room to work with (especially when lowered less than stock 200mm).
Probably wouldn't be able to get it lighter than a Zeb (two crowns after all), but I bet they could get it close with a dedicated effort.
Tough product marketing positioning though, all of the manufacturers have sunk to much $$ into their 38mm single crown platforms and a lightweight DC would overlap too much from a use-case perspective.
For all intents and purposes, I don't notice it during descents in the bike park. If I actually pedaled the bike more, might be annoying in tight switchbacks going uphill, etc. But I never notice the turning radius on bike park laps.
I think the headtube for the carbon spires/patrols would be way worse (way fatter headtube).
In fact maybe that the big impetus to move to the inner air spring tube. They really wanted the holes for oil movement for better lubrication, but that means the entire air spring either ends up relatively short/small (and hard to service) with the "end" cap above the holes, or it gets its own tube like the damper and can be full length (and easier to service).
I also wonder when the new brake will launch—maybe that's still in proto though.
I wonder if adding surface area to the high pressure piston seals added more stiction than they could handle on a big ~38mm (whatever the inside diameter is) spring. The Fox 40 seems to be able to get the springs right with even larger tubes, though... Maybe they just like the idea of isolating the spring to allow coil to air swaps.
Finally, the new BoXXer benefits from so-called Lower Leg Plugs, a detailed image of which we don’t have to hand. However, this has an equivalent function to the Pressure Relief Valves implemented on the latest Zeb, Lyrik and Pike forks, allowing a release of air pressure that may have built up in the lowers during riding. It’s possible SRAM switched to the tweaked design in order to circumvent any potential patent infringement.
Maybe its because I run a 40mm stem, not sure.
I started playing with offsets in 2019 after I noticed the Syndicate bikes were running the Morc offset crowns from MOJO Rising on the fox 40. At that time the offset was 58mm.
The Morc crowns were 50 or 55 offset.
I really enjoyed the 50mm offset, but found I really had to oversteer the bike in the corners, but the front wheel traction breakaway window felt huge. The 55, I felt the rider input was alot more responsive, but the traction breakaway window was a bit vague and had a narrow window.
I got on the Ohlins DH 38 to test for most if the 2020 season with a 54mm offset, and it was improved but not perfect.
Fox dropped the current gen 40 with a 52mm offset, and I really felt that it was the sweetspot for what I was looking for.
Stem length and head angle also play a huge roll here. I started on a 45mm stem option, but eventually went to a 50mm to help weight the front wheel a bit better.
Keeping in mind I generally prefer a longer reach bike. I'd say a shorter offset would be more beneficial for riders who prefer shorter reach numbers as it calms the chassis down in the corners when the riders weight balance ratio is higher.
Geo tab here: us.nukeproof.com/products/2022-giga-297-carbon-rs
33 inseam and 182 wingspan (178cm tall)
What bar rise are you running, and what's the width?
Does the rubber eventually go away and disintegrate? Compress and not do anything?
What are the symptoms of worn out buttercups?
You'd have to compare the small bump compliance with and without them to tell the difference and if they're included in 200h service kit, I'd bet they can last quite a bit more than that
RockShox: Yes, we thought you might.
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