First look: Formula’s buttery ThirtyThree suspension fork

For the past two years, Formula have been teasing us at the annual trade shows with talk about and pre-production samples of a new suspension fork.  Dubbed the ThirtyThree, the Italian company’s first suspension fork uses ever so slightly larger than normal 33mm stanchions and magnesium lowers for the 80-100-120mm (via internal adjustment) cross country platform.  Drawing on tuner Fiorenza’s extensive motocross experience (with the likes of Paioli and others), the ThirtyThree pairs a couple of coil springs with a main air spring to keep the early stroke active and air pressures low.  At an eerie 3.33lb (1,510g actual for a cut 1 1/8in steerer with 15mm thru axle), Formula’s freshman effort sure sounds good on paper- but how ’bout on the trail?

To crib from Tyler’s 2011 Interbike post:

To justify introducing another suspension fork into an arguably crowded market, Formula had to offer something different. The air pressure settings here, in addition to having a nice section on the label to write your preferences for quick reference, are only 60% to 70% of the settings recommended by Rockshox on their stickers. Here’s why:

2012 Formula Thirty3 mountain bike suspension forks weights photos and technology

This highly technical explanation from one of their engineers shows that when you rely on higher air pressures, you get more ramp toward the end of the travel (represented by the curve starting from 50psi on the left). If you could use just 5psi (bottom curve starting at 0), you’d have a much more linear curve as you moved through the travel.

By using the coil “helper” spring, it handles the first 40mm of suspension movement very easily before activating the air portion of the suspension. It’s also perfectly linear in its progression. This is represented by the darker line that goes from 0psi to meet the curve for 50psi. Overall, they claim the result is a more linear feel than if you had to rely on a higher overall air pressure. Presumably the “helper” spring negates the need for a negative air chamber, and the lower pressure is why it needs the rebound assist spring.

Got it?  Good.

Despite its low weight, the ThirtyThree is an impressively solid feeling thing- even before being mounted.  Everything that can be touched is nicely machined.  In a surprise move, Formula have foregone any quick release on the front axle- you’ll want a 6mm Allen key to get the front wheel off.  Figuring that you’ll have a mini tool if you have the stuff to fix a flat, Formula’s logic is hard to argue with.  Any misgivings on my part were overcome by the remarkable smoothness with which the axle threads into the far leg: manufacturing tolerances are obviously tight and things just plain line up.

The ThirtyThree’s external adjustments are pretty standard: air pressure, compression damping/lockout, and rebound damping.  Everything is more or less where you’d expect with a nice feel.  The air pressure recommendation label (complete with space for your own setting’s) extends down to 120lb (hooray!) and even has a place for the owner’s name (just in case).  With light rebound damping, the lockout open, and the recommended air pressure all set, it’s time to ride.

A little (140lb) guy, it’s often hard for me to find forks that work well on small bumps without blowing through their travel on moderately-sized hits.  It’s here that Formula’s design (and the effort spent on low friction seals and custom bushings) really shines.  At the recommended air pressure (about 50psi), the ThirtyThree feels for the first inch or so like a broken in trail fork.  When approached at speed, roots and chicken heads are gobbled right up.  After that, the fork becomes nicely progressive, without wallowing or bottoming out on bigger stuff.

Compared to the 120mm SID XX it replaced, the Formula is both stiffer and more active.  So much so that it’s easy to forget that it’s ‘only’ a 120mm fork and ride it like it has an extra inch or more in reserve.  There has been a bit of oil sneaking by the main seals- but better oil out than dirt in and not so much that I’m worried.  In the few short weeks since its arrival, I’ve been seriously impressed with this fork.  While its weight and Italian heritage had me expecting a somewhat harsh race fork, the ThirtyThree seems geared much more towards long rides and races on rough terrain- something that suits me very well.  Around $1,050 from just about any shop in the US.  Look for a long-term review next spring…

Edit:  29er and 650b versions are not currently available, but may be made if global demand dictates…



13 thoughts on “First look: Formula’s buttery ThirtyThree suspension fork

  1. Fox has also went with a more linear air spring in ’13, to the dismay of other reviewers who try to get some progressiveness back by putting float fluid in the air chamber, to reduce air volume.

  2. Manitou is always overlooked as a cutting-edge fork manufacturer, but they are. One of the first to embrace platform-valving, through-axles, and over-sized steerer tubes- while everyone else just put new stickers on the same old crap.
    That said; I love my RS Revelation and my Tower Pro. I am excited to give this Formula a go.

  3. Really amazing fork but the pressure could not be used as told by formula! had to put 5 or 10 more psi depending on the trail! It feels great!!! Compared to a RS Sid Team..

  4. I’ve been riding a 33 for a couple of months now and I am very impressed, you’d have to ride one to believe how smoth, sensitive and stiff this thing is -more than a F34-. I am loving it more with every ride.
    Formula should take the risk and make a 29er version available right away, and a 150mm 650b version soon.

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