I have been riding the new fancy red RockShox BoXXer World Cup on my Pivot Phoenix since late August on everything the East Coast has to offer. I spent a lot of time smashing out bike park laps in the dust, riding cold, muddy rocks and everything in between. I am coming off of a 2017 Fox 40 RC4 so this has been quite a big change. While the Fox fork has more adjustment, I think that they are both equally easy to initially set up. The chassis on the Boxxer is noticeably more compliant than the 40, and the amount of support throughout the stroke seemed to be about the same.
The Rockshox Charger 2 damper is right up there with the best of them. It offers a great range of adjustment to get your fork feeling perfect. While it does not offer as many clicks as a Fox Grip 2 damper, the overall adjustment is fairly similar so while you won't be able to be quite as precise, you will be able to cover the same ground with the adjustments. With 5 clicks of high-speed compression, 18 clicks of low-speed compression and 19 of rebound, you are sure to be able to get the feeling you are searching for.
I have found that the fork has been one of the most supple forks I have ever ridden and offers a ton of support in anything from diving into a high-speed bike park turn to riding the steep, technical, muddy rocks we have here on the East Coast. When comparing this damper to the other top of the line dampers on the market, it is extremely competitive but I wouldn’t say hands down the best. However, this is only one part of the package. This damper paired with the DebonAir spring is definitely something to look twice at.
The DebonAir spring that Rockshox is now putting in the Boxxer is much more tunable than before. The larger volume allows for the fork to be more linear with no volume reducers, so if you are a lighter rider you will still be able to get a full stroke. But you can pack it full of volume reducers, have an extremely supple fork(thanks to the DebonAir) and almost never bottom it out.
I am 160lbs and I have my fork set up with 125psi and 3 volume reducers. But there is very handy chart sticker on the back of the fork leg to help with a baseline psi for your weight. The Boxxer is very good at blowing through the first ~ 30% of the travel to provide that supple feel, then it starts to ramp up to make sure your fork is not diving under braking or in corners, and finally ramping up hard at the end so that you don’t slam the fork unto the bottom out bumper when you go a bit too far while launching. This comfort also has a lot to do with the chassis of the Boxxer.
My personal favorite thing about the Boxxer compared to a 40 is the chassis. Rockshox has always been known for not having as stiff of a chassis compared to Fox and the Boxxer is no different. For lack of better words, the Boxxer is more flexy. Basically, I look at it like this; if you are racing DH on gnarly tracks, if you don’t have any issue with arm pump or are heavier, you will probably be more happy with a 40. But if you are mainly riding bike parks, have trouble holding onto the grips by the end of a day, or are lighter you will be stoked on the Boxxer. Not to say that the BoXXxxer is not a race fork (have you seen who won the World Cup overall?) or that the 40 is not good for fun riding(check out Cam Zink) but that is how I would explain it in the most basic way to someone who is on the fence between DH forks.
Something to note is that the new BoXXers have a new DH hub standard. While it is still the same old 20x110mm spacing the post mounts for the brake caliper are pushed out an extra 5mm to allow for the hub flange to also be bumped out and create a stiffer wheel. There are still a lot of companies that don’t offer this spec hub, but don’t worry! There are some aftermarket options for ya to use any standard 20x110 hub. Check out this guy: Problem Solvers Fat Fork Disc Rotor Spacer. Another thing that I really like about the new RockShox DebonAir forks is that you can just use a cassette remover tool to change out volume spacers which is much easier than trying to get a good grip on the top cap of most forks and also there is no need for any special tools.