Despite the boom in fat-bike sales a few years back, suspension companies seemed slow to embrace the fuller tyre bike. In fact, since the RockShox Bluto debuted in 2014, there has been no other fat offerings from the big names in suspension, until now.
I've put the established RockShox Bluto up against the mighty Manitou Mastodon to see how they measure up and which comes out on top.
RockShox Bluto RL
At the height of the fat-bike boom in 2014, RockShox took the bold move to introduce the first mass-market fat-bike-specific suspension fork. In doing so it brought in the widely accepted 150mm front-hub sizing and heralded a shift from snow-specific and brutish/belligerent trail-riding to a more capable and familiar feeling ride.
Based on the RockShox’ successful Reba and Revelation fork models, the Bluto was familiar to most riders straight out of the box. With options of either 80/100/120mm travel, pretty much all fat-bike frames of the time could be catered for without compromising on its suspension-corrected geometry.
A simple lock-out lever at the top allowed for a simple on/off compression for tackling climbs and flat terrain and RockShox’ Rapid Recovery Rebound Dial to deal with bump recovery can be found at the base of the stanchion.
Adjustability is limited, although you can tinker with bottomless tokens to change air volume and air spring compression. It's also possible to swap out the stock damper for RockShox' high-end RCT3 Charger Damper, although this isn't offered as a stock option and isn’t something I have tried myself.
RockShox Bluto RL ride performance
Having spent a lot of time on various Bluto-equipped fat bikes in all conditions, I'd recommended it as an upgrade for keen fat-bikers who are looking to squeeze a few more thrills from their trails.
The change that suspension makes to the sensation of riding fat tyres over any surface can’t be underestimated and my time on the Bluto has opened my eyes to the potential fun that can be had on big rubber.
The simple controls have made set-up a doddle and once you're at your optimal setting it can be forgotten about.
Anyone concerned about adding weight to an already hefty front end (due to the additional rubber) should note the claimed 1,796g is jaw-droppingly light when compared to the 1,666g of a 29-inch RockShox RS1.
- £600 / €799 / $719
Manitou Mastodon Pro
Given the three-year lull between the release of the RockShox Bluto and its first serious fat-fork competitor, you'd be right in expecting something pretty different.
For starters, Manitou has embraced the recent expansion in fat-wheel standard to encompass traditional 26in size as well as the new 27.5in fat hoops, which require some pretty huge clearances when shod in 3.8in tyres.
Options for travel will also have most bases covered with a range of 80/100/120/140/150mm. To compensate for any additional flex from beefier wheels and tyres the decision was made to base the fork around 34mm stanchions.
While fewer riders will be familiar with Manitou’s suspension technology, it has cherry-picked some of its best for the Mastodon.
The Pro model employs a Dorado Air Spring from its popular Mattoc fork, HexLock axles and its distinctive rear-facing crown arch.
The defining addition is the hugely tunable MC2 compression damper, which is shared with Manitou's mid- to high-end forks. This uses a red low-speed compression dial and smaller black dial for the high-speed compression settings — adjustment is limited to four clicks per dial.
Manitou's IVA (Infinite Volume Adjust) allows for a wide variety of tuning options by allowing spacers to be positioned above and below the air piston. For anyone who takes their suspension setup more seriously, then this can be replaced with the IRT (Infinite Rate Adjust) to fine-tune the mid-stroke rate independently of bottom out.
Manitou Mastodon Pro ride performance
I was impressed by the ride quality of the Mastodon. Plus, it's buttery smooth straight out of the box and required very little faff in its initial setup.
The MC2 compression dial makes on-the-fly adjustments extremely easy. With only a little more time under the hood, the Mastodon's potential becomes apparent. And this is without feeling the need to invest in an IRT kit.
While fat-bike tyres can be notoriously squirmy, especially at lower pressures, the bulked-up stanchions dial back a noticeable amount of flex making for more accurate steering and feedback.
The HexLock SL axle’s need for an 6mm Allen key adds some hassle to wheel-removal compared to a simpler quick-release style, but this is a small gripe when looking at the bigger picture.
- Manitou Mastodon Pro: £750 / €878 / $1,070 / AU$1,367
- Manitou Mastodon Comp: £500 / €577.49 / $713 / AU$911
Conclusion
If you're looking for ways to liven up your fatty, then some front-end squish is definitely the way to go. Either of these forks are great upgrade options, so you won't be disappointed with how they revolutionise your ride.
The Bluto is a lightweight contender with a proven track-record in reliability. For riders transitioning from rigid setups or are unfamiliar with suspension it's simple and not at all intimidating to get to grips with.
If your fat bike comes with Bluto’s specs on its build there won’t be many reasons to upgrade… that is unless you want the very best in fat-bike suspension.
The Mastodon has taken the Bluto playsheet and filled in the gaps to meet the demands from today's riders. While Manitou forks are less ubiquitous than RockShox' on the trails, Manitou has been quietly building a reputation for versatile and reliable suspension options. And it’s great to see some of the best tech from its suspension line-up make it to its fat-bike-specific fork.
Based on back-to-back riding on the same test bike, the Mastodon really outshines the ageing Bluto with stiffness and a huge range of adjustability. While all the adjustability and the stiffer design comes with a weight penalty, I think it's a price worth paying.
RockShox may have erected the bar, but Manitou has raised it a few notches. I sincerely hope the Bluto is in line for a refresh, it will be interesting to see if it can bounce back.