Custom shock tuning has never been more affordable or convenient

Product Overview

Formula Mod coil shock


  • Low breakaway force and high oil volume for controlled damping. Two additional CTS valves included in the price. Firm lock out and intuitive easy to understand external adjustments.


  • Oversized reservoir could cause fitment issues on some frame designs.


Formula Mod coil shock: first ride review


Price as reviewed:


Formula Mod coil shock features Compression Tuning System with three distinct flavours. Bladder-backed reservoir increases sensitivity and reduces heat.

Read more: Buyer’s guide to the best shocks, coil and air

Formula Mod

Formula Mod need to know

  • The new Mod coil shock from Formula features its CTS (Compression Tuning System) with three distinct flavors
  • The compression valving and damping curve can be changed in a matter of minutes by the rider
  • A bladder backed reservoir increases sensitivity and helps reduce heat buildup
  • Available in standard 210x55mm, 230×65 mm sizes with 185x55mm and 205x65mm Trunnion mount options
  • In addition to CTS, the Mod shock features external rebound and compression adjustment and a lockout lever
  • Coil springs available in Ultraviolet or Titanium finishes, with rates from 300lb to 600lb in 50lb increments
  • Claimed weight for the 210×55 shock with a 300lb spring is 670g

Product launches tend to follow a set script. Brands fly media in from all corners of the globe to present their latest product to what they hope is a captive audience. The format is formulaic, and invariably it’s a sleek power-point presentation in a stuffy hotel normally reserved for wedding receptions and conferences.

Even when the location changes; the routine tends to stay the same. The lights go down, the projector fan spins up and the audience knows to nod along politely to get through proceedings as quickly as possible. These definitely aren’t forums for discussion or debate, as enquiring questions just delay the process.

So imagine my surprise when I walked in for a one-to-one presentation with Formula and was greeted by Vittorrio Platania sitting next to a tool chest, vice and Formual’s latest product, the Mod coil shock. The reason for the departure from the product-launch playbook? Formula wanted to show firsthand just how easy it is for riders to customise the compression damping on its new shock.

If you are familiar with Formula’s mountain bike forks you’ll already know that its CTS (Compression Tuning System) allows the rider to make large-scale changes to the damping curve of the fork. Want more low-speed support and less-high speed damping, pop in the Gold CTS valve. Alternatively, if it’s maximum small bump compliance with additional mid-stroke support and extra bottom out resistance that you desire, switch to the red CTS valve. No strip down and rebuild required, just pop in the specific CTS valve and go ride.

Well, it’s the same deal with the new Mod shock, but instead of having seven CTS valves to choose from it has three. Formula tunes the shim stack on the main piston to the specific frame design, then the shock ships with the medium CTS installed, with Firm and Soft CTS assemblies also in the box.

The shock is a single-tube design with a large 30mm piston that pushes a lot of oil through the CTS valve. It also has a bigger than normal reservoir, which is pressurised with a regular shock pump. Instead of using a traditional IFP (internal floating piston) to stop air and oil mixing in the reservoir, Formula has opted for a bladder design. The key advantage being, that you eliminate the initial stiction associated with the IFP seal, so the breakaway force required to get the shock moving is much lower, which in turn improves traction. It also means there’s less heat build up as said seal isn’t constantly rubbing against the inside of the reservoir when the shock is active. Less heat build up means more consistent damping. And it is this specific trait that makes the Mod coil shock an even better choice for enduro racing than Downhill. In DH racing, runs last a maximum of 4-5 minutes, but in enduro racing stages can be up to 30min long, especially for regular riders, so the shock can get seriously hot.

In addition to the broad-brushstroke CTS tuning the Mod shock has all of the fine tuning you’d expect on a conventional design, so you have external low-speed rebound and compression adjustment at your fingertips. There is also a lock-out lever that’s really effective, making it a welcome addition for long lesions and steep fire road climbs.

Spring rates range from 300 to 600lb in 50lb increments, and you have the choice of ultraviolet or tratinum finishes, (and both are titanium springs to save weight (waiting for confirmation of this). In fact, with so much colour coordination going on, the off-yellow bottom-out bumper looks somewhat out of place. Formula was adamant however, that it had to be this colour to get the correct characteristics. And I believe them, because being Italian, if they could have achieved the same level of performance from a black or purple bumper they would have moved heaven and earth to do so.

Claimed weight for the Mod shock is 670g, and that’s for a 210x55mm shock with a 300lb coil spring, so unless you’re really small or really light, the Mod is going to be heavier than claimed.

How it rides

My first run on the Formula equipped Orange Switch 6 was with a lighter spring-rate and the firm (green) CTS valve. It’s not a combination that I’d normally run, especially on a less-progressive suspension design like the Orange, but Formula was claiming that its larger volume reservoir and dedicated bump-stop made the shock more progressive, so I had to put this to the test. Grip and control were impressive even with the firmer damping, and even with the soft spring rate the shock never bottomed harshly. Not even a hit of metal on metal, even though I was tying my best to make it chime. So the bottom-out bumper really does work.

Moving up to a more suitable spring rate for my weight and the stock medium (orange) CTS assembly gave the Switch 6 a more balanced ride, with a little more pop when preloading the suspension. There was less high-frequency vibration through the chassis and less fatigue towards the end of each run on my chosen test track. It felt like a great race set-up and one that I’d be happy to run day in, day out. Then, out of curiosity, I switched to the soft (gold) CTS valve for one last run and the increase in dynamic sag and improvement in grip and comfort were instantly noticeable. Chassis stability didn’t seem to be compromised either, especially once I added some low-speed compression with the external adjuster that sits just above the CTS valve.

And therein lies the beauty of Formula’s CTS design. To make these large scale changes to the damping curve, a shock would normally require a full strip down and rebuild, and a well-equipped team tuck to do it. But we achieved a similar outcome in a matter of minutes with just a couple of basic tools. To see just how easy a CTS valve swap is, check out the video here. And for once, it’s not just another uninformative shreddit that’s used to break up a launch presentation.

With CTS, custom shock tuning has never been more affordable or convenient. And given my initial impression of the Formula Mod shock, it looks like Formula isn’t just set to rewrite the launch presentation playbook, it now has its own chapter in the suspension tuners’ handbook too.