Manitou Mezzer Pro | Just The Right Amount Of Tuning?

On the fork you’ll find low and high speed compression settings, rebound, air spring… and a valve labelled IRT, which stands for “Infinite Rate Tune”. It’s basically an air chamber that takes the place of volume spacers in other forks and, naturally, using a valve and shock pump makes it much quicker that removing a top cap and bolting on chunks of plastic.

The air spring is actually filled from the bottom of the left leg, which charges up not only the spring, but also a negative spring air chamber at the same time. The negative spring pulls down slightly on the upper legs, letting them overcome stiction and start moving a bit more easily.

The IRT is the valve at the top of the left leg, where you’d normally assume tha air spring is, but it is clearly labelled. Procedure is to fill the IRT first, then the air spring, both with recommended pressures on a chart.

Documentation was little a bit lacking during my review period. That said, I also had the backing of Hayes Group engineers and marketeers, some of whom I got to talk to with video calls. While those calls were very useful, presumably they’re not something on offer to their customers? Mostly, I just had the setup guide to work from, which is here. It’d be nice for some version of that chart to go on the back of the fork leg.

“PRESSURIZE IRT CHAMBER FIRST” is the last thing it says in the setup section, so this definitely isn’t written for the kind of people who are just going to jump in without reading everything carefully. It’s enough to go from though, and to start with I went with the recommended settings. That yielded a sag between 25% and 30%. I usually run around 30%, and reduce it for shorter travel forks; or the baked height of summer when I’m likely to be going faster.

At 170mm, these forks seemed unlikely to run out of travel quickly… I decided to try them as is, but left all the compression open for the first ride. They’re also available in 160mm or 180mm versions.

The Ride

It became immediately apparent on the first descent that this is an absolute bruiser of a fork. Supple, but solid as a rock and not prone to hanging on things or getting knocked off line. Even months into the test, when I was well used to it, during a particularly prolonged and choppy crash it struck me how solid the bike felt with the Manitou Mezzer Pro upfront (just before I separated from bike and pancaked into the bank of the stream bed I was riding down – not the fork’s fault).

I only ran this on a Nukeproof Mega, which I’d not ridden before, so there’s been work to do in terms of separating the character of fork and bike. Neither is subtle or delicate, and in those respects they’re a good match for each other. Both felt rock solid (in the good way!) down every descent, and both are definitely biased toward descending rather than big XC loops.

The Manitou Mezzer Pro compression damping is very much from the school of “tuning, not lockout”, and as with Cane Creek’s Helm, I ended up running low and high speed compression open most of the time, or with just a few clicks. As such, while it wasn’t terrible stood up on climbs, it was more suited to seated climbing than mashing out of the saddle. Bear this in mind before you whack that 36t chainring on.

The negative spring makes them very smooth in the initial travel. Initially it seemed a shame it can’t be adjusted independently of the main air spring, but I found it plenty smooth enough and didn’t really miss the tunability compared to, say, a Formula Selva R or Cane Creek Helm.

Where I did struggle a little was with the IRT, but it’s important to stress that at just under 80Kg, I’m not the heaviest rider. Historically, I seem to be optimised for 160mm of travel. Every 170mm fork I’ve run, I’ve struggled to use the last 10mm, and this was true for the Mezzer Pro too.

Lowering the main spring pressure to get 30% sag did a little to get me using more travel more consistently, but still almost never full travel. To be honest, I don’t obsess about this, because it can depend on where and how I’m riding that day. If the fork feels good and is using most of the travel through the rough and dropoffs, that’s fine and it’s nice to have a bit extra in reserve.

For the sake of completeness though, I wanted to see how tunable it was, and consistently getting full travel seemed a suitable goal. In the setup guide, it specifies -10PSI to the IRT for trail riding, and +10PSI for downhill. Dropping 10PSI from the IRT didn’t change much for me in terms of travel use; it’s really a very effective bottom out bumper. Nice to have when you’ve set your fork up but are pushing your limits and trying new things.

Some other articles and documentation on IRT equipped forks seemed to indicate a wider range of pressures. So, after starting with the default of just under 54PSI in the air spring, and 83PSI in the IRT, I tried dropping the main spring pressure first. That resulted in more than 30% sag and predictably, a slightly boggy, mid-travel feeling for my riding style and the steepness of the trails I was on. So, setting the air spring back to a minimum of 54PSI, I set about experimenting with the IRT. Many rides later, I ended up with 70PSI in the IRT and 54PSI in the main spring. It still tended to leave a bit of travel on the table, but it was consistently using more and still felt good.

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Apart from that one way-too-soft one, in all the experiments I did with the air spring, the Mezzer Pro was good at resisting mid-travel bogginess. This also manifested in successive big hits, where it seemed to recover quickly and never sit in the travel.

Between me and a housemate borrowing the bike regularly, this fork got absolutely hammered for several months straight, but didn’t stutter once.

On the whole, the Mezzer isn’t as comprehensive or plush as a Selva, nor as simple as a Pike or Lyrik. I’d put this on a par with Cane Creek’s Helm in this respect – it can take a little effort to get the right settings, and overall it has a bias toward going faster and hitting things a little harder. Way overkill if you live somewhere flat and made of dirt, but if you live anywhere steep and/or rocky, it has a wide enough variety of settings that’ll work.

Overall

The Manitou Mezzer Pro is stiff, firm, accurate and feels light relative to its burliness and travel. It’s not quite the most tuneable fork out there, nor the least. This is on a good level for people who want to be able to tweak their suspension, but not obsessively. Well suited to riders who want to plough through the choppiness without tuning it all out, knowing they’re on a solid platform.