In spite of the hefty amount of rubber, plus bikes will still benefit from suspension. Thanks to the addition of Boost spacing for forks, there are a few forks that will clear the massive tires. But forks built specifically for the plus standard? There are a lot fewer options in that category.
When Manitou announced they would have a fork with Boost spacing, they opted to create a fork based exclusively on plus sizing. With the air spring and damping tuned to the added heft and kinematics of plus tires, the Manitou Magnum could be big in the mid-fat world…
Using a similar 34mm chassis as the Manitou Mattoc, the stanchions are inserted into a purpose built lower assembly with Boost 110x15mm axle spacing, Manitou’s Reverse Arch, and a forged deep bore hollow crown with 1.5″ tapered steerer. Essentially that means the Magnum should be stiff. And it is. It’s stiff enough that any flex would be imperceptible thanks to the flex of the plus size tires. But the stiffness does deliver when you are pointing the bike down an ugly chute and getting rowdy on the bike. The burliness of the front end will make you forget this fork is just over 4.5 lbs.
To keep the two ends of the fork tied together, Manitou uses their QR15 Hexlock thru axle. On one hand, the Hexlock QR15 is extremely simple to operate, but on the other – it can be a little tricky to get the hang of for some. Key to the axle’s operation is that it is oriented properly on insertion. To make this as easy as possible, the axle is printed with a big “up” with a line through it. this ensures the t-shaped prong on the end goes through the dropout properly. From there, a simple quarter turn of the axle locks the ‘t’ in place, and a closing of the skewer lever locks the wheel in place. The Silver bezel on the axle allows you to set the preload by unthreading it to make the axle clamp tighter.
It’s one of those operations that’s really easier to show than explain. It’s also something that if you don’t fully understand how to operate it, it could be a source of frustration as I’ve heard from a few people that have run into it without the instructional card supplied with new forks. That said, once set up it’s one of the fastest thru axle systems out there.
After familiarizing yourself with the axle system and the multiple suspension adjustments (Dorado Air, MC² Compression adjustment, TPC+ rebound adjustment, Hydraulic Bottom Out, and IPA platform, and IVA volume adjust) you’ll hit the trails and probably notice you’re not getting all of the travel out of the fork.
Well, not really, but it will look like it.
If it’s been awhile since you’ve ridden a Manitou fork, you have to remember that the Reverse Arch design means you never will see that o-ring reach anywhere near the fork crown. If it did, you’d have a broken reverse arch as it smashes your downtube. That doesn’t mean the Axle to Crown measurement suffers – just that Manitou forks have more stanchion exposed than the actual travel and shorter lower legs. The result is the same, just moved down the stanchion slightly.
Even once you realize you won’t be using up all of that stanchion, you still might have some trouble reaching full travel. At 155 lbs with gear, I was already running the Hydraulic Bottom Out resistance at the lowest setting, but still wasn’t quite there to the full 120mm of travel. If you’re having the same issue, Manitou walked me through the ‘air spring reset’ process. When you attach a pump to the Dorado Air Valve it connects the pump to the positive air chamber while simultaneously opening a mechanical valve to the negative air chamber.
With the pump attached, if you pull the fork to full extension it will ‘reset’ the fork to its full height and reset both springs. Then inflate to proper pressure, and you should be good to go.
Then there is also the Incremental Volume Adjust that you can use to tune the air spring to your liking. Already tuned to lesser impacts due to the big tires absorbing more of the trail, further adjustments can be made by moving the IVA spacers. Mine was shipped with the piston in the highest position which makes for the most linear air spring with a bigger chamber. If you want a more progressive fork you can pull off the spacers and put them above the upper piston head, which moves the upper piston down and makes the air chamber smaller. It seems a bit reversed compared to the RockShox Bottomless Tokens, but the IVA spacers aren’t taking up room in the air chamber to make it lower volume, they are repositioning the upper piston which is what changes the volume. With the right socket, this adjustment can be made in a few minutes for some simple tuning.
Combined with the MC² compression, TPC+ rebound, and IPA Incremental Platform Adjust, this is one of those forks that may have more adjustments than many riders need. However, that also equates to a platform that is extremely versatile for many different riders. Even with all of the options, it was fairly easy to get the Magnum performing as desired. Using minimal IPA, the IVA spacers in the highest volume setting, and about 65 psi in the fork, it settled in nicely at the front of the Advocate Hayduke.
Takeaway:
If you’re expecting something radically different from a plus size suspension fork, this isn’t it. Which is probably the point. The Magnum seems to deliver performance worthy of any normal mountain bike, just super sized for the bigger wheels and tires. The result is a bike that, other than the increased grip and tire footprint, performs as well as many other mountain bikes.
Manitou has delivered a suspension nerd’s dream fork, built for plus size. It has almost every adjustment you could want, it’s fairly light for a massive 34mm fork at 4.6 lbs (2.09kg), and it delivers an impressive ride both in stiffness and suspension quality in 27+ or 29+, all for $899 retail.
One thing is for sure – the Magnum shows that Manitou is still a big player in the suspension game.
For more tech details make sure to check out our first look, here.
