We got a good detailed look at the SR Suntour TACT automatic suspension on Tom Pidcocks’s World Cup-winning Pinarello mountain bike just a few weeks ago. But now SR Suntour has made this automate electronically-controlled XC MTB suspension official, and shared a good bit more detail with us. We were already impressed with its race-winning performance. But now, having a better look at how surprising simplicity makes it all work, I’m more intrigued than ever.
Plus, now we know how much it will cost and when it’s coming to a bike near you…
SR Suntour TACT automatic electronic XC MTB suspension
When I caught up with the new Pinarello Dogma XCs of Tom Pidcock and Pauline Ferrand-Prevot in Nové Město na Moravě, I was first surprised to see such tidy integration into their cross-country race bikes – just one small wire exiting the fork crown and just one wire coming off a slightly larger control box on the rear shock. But really caught my eye was what was missing – the system had no external buttons, no display, and no bulky external control units or battery. These two top riders obviously could trust that the automated suspension control would work so reliably, that they couldn’t even deactivate it during a race if they felt they weren’t getting the most out of the system.
Now, knowing that just one 3-axis accelerometer controls the entire system makes that even more impressive.
What makes up an automated TACT suspension setup?
The SR Suntour system is comprised of three simple elements, each wired together for the fastest performance, fastest communication, and long battery life:
- the Axon 34 Werx Boost EQ 29er fork with a hollow carbon crown, magnesium lowers, plus the single TACT accelerometer sensor, the brains of the automated suspension system, and a compression valve actuator in its right leg on top of the PCS hydraulic damper – available with 100-120mm of travel and with external low-speed rebound adjuster;
- the Edge TT rear 2-chamber air shock with a compact external integrated actuator box – with external low-speed rebound adjuster; and
- a USB-C rechargeable central battery that is wired to both sock & fork – SR Suntour provides an external solution that integrates under a special water bottle cage, but Pidcock & Ferrand-Prevot race with an internal battery that can be charged via the external wiring points.
How does it work?
The system simply works by using the single 3-axis accelerometer in the fork crown to determine the angle of attack of the bike (is it going uphill, on the flat, or downhill), monitor impacts coming in from the front wheel, and differentiate force applied from the rider at the bar into the fork. From that input data and a 1-8 TACT support level preselected by the rider via a mobile app, the suspension automatically opens and locks out to maximize efficiency – varying both fork & shock low-speed compression depending on need, not just fully open or fully locked but also a medium in-between pedal platform mode, too.
It all happens so fast – a claimed 4 milliseconds – that the suspension apparently remains active on technical climbs to absorb every impact but is able to stiffen itself up as the rider’s pedal stroke comes down again, or the moment they get out of the saddle to stomp up a climb.
You don’t have to think about the suspension at all. Just pedal.
SR Suntour tells us that on the technical 3.8km long XCO course in Nové Město, Pidcock’s TACT suspension automatically changed position 150 times each lap.
TACT suspension still requires a regular air pressure setup to dial in rider weight (with the compression settings open), and you still get external rebound adjustment to tune in for the desired terrain. Then in the SR Suntour TACT companion app on a mobile phone, the rider picks a level from 1-8: 1 & 2 offering max comfort, middle settings balancing comfort with efficiency, and 7 & 8 prioritizing XC-race-ready pedaling efficiency above all else. But once it is set via built-in Bluetooth connectivity, the TACT system does not require a mobile phone or app to function. It is always on – activated by movement, and returning to sleep mode when the bike doesn’t move – and will stay in the preset mode until you change it.
The rumor is that the pro racers tend to stay near the higher numbers, but sometimes pick a lower TACT Mode level for more technical racecourses – think: maybe 8 for XCC & 6 for XCO.
Tech Details & Who is it for?
TACT is a fully-automated electronic 3-position low-speed compression suspension control system – open, medium, firm – that operates both front & rear suspension from a single sensor and single processing unit – an example of SR Suntour’s refined simplicity guiding principle… “high performance made simple“. TACT is a standalone system that does not need any other device to control it, but it can be custom configured via an iOS/Android mobile app. It is offered on the 100/110/120mm Axon 34 Werx Boost EQ 29er fork and the Edge TT rear shock (available in 165×40/45mm, 190×40/45mm & 185×50/55mm). Total additional weight compared to a non-electric cable-activated remote suspension lockout system front & rear is an extra 198g.
Obviously, XC racing is the most obvious application since it has been raced to 4 XCO World Cups and an Olympic XCO Gold medal all by Tom Pidcock in the last two years. But SR Suntour describes the automated TACT suspension system as delivering “more traction, more control and improved focus on riding“, making it a technology suitable for “every type of bike user“.
The trick is, the tech is only available now in super top-level XC racing suspension components, is only currently tuned for 3 top-tier XC race bikes, and the control algorithms that make it work are tuned exclusively for short-to-mid-travel cross-country bikes.
SR Suntour TACT suspension – Pricing, options & availability
And since this isn’t exactly something you can just go down to your neighborhood bike shop and bolt on as an upgrade, it’s still going to be limited in application. But SR Suntour has given us a retail cost for the automated TACT suspension system – 4990€ gets you the Axon34 Werx TACT fork, the Edge TT TACT shock, and the bottle cage with the integrated external battery & wiring.
Officially, it will be available starting late this summer through “TACT Pioneer Program Member” bike companies. We are told to expect that to mean ultra-limited edition OEM builds through bike makers who have already partnered with SR Suntour for racing development, and likely some even more limited retrofit availability. It should already at least be able to be installed on the new Pinarello Dogma XC, current Scott Spark, and probably the previous generation BMC FourStroke Pidcock raced last year.
But let’s also put it this way… even though there is now a TACT cage & battery to fit most bikes, TACT isn’t officially in the 2024 SR Suntour product catalog just yet.
