Trek delivers more Formula 1 suspension technology

Thru Shaft is the fastest-responding shock on the market, Trek claims

Trek has again partnered with Formula 1 suspension expert Penske for its latest rear shock technology, dubbed Thru Shaft. With the new tech, Trek claims to have improved upon its Penske-derived Re:aktiv shocks with faster response, smoother transitions and better ground tracking.

The Thru Shaft slides through the bottom of the rear shock for increased tracking and response according to Trek
Sterling Lorence/Trek Bikes

Thru-shaft technology has been used successfully in all sorts of motor racing including Indy, Le Mans, Formula 1 and MotoGP. 


More ground contact

Mountain-bike suspension has two main purposes. The most obvious, due to the name, is to ‘suspend’ the rider from bumps and hits. The second but equally important purpose is to maintain traction by tracking the ground over the aforementioned bumps and hits. Increased traction allows better cornering, climbing and all-around control. 

Trek touts decreased rear suspension lag for more control and traction over rough terrain
Sterling Lorence/Trek Bikes

The Thru Shaft is aptly named – it’s a shaft that slides out of the shock body between the lower shock mounts as the shock is compressed. Trek claims it eliminates the need for an internal floating piston (IFP) that compensates for oil displacement in traditional dampers. 

Because the shaft physically slides out of the shock body, the internal volume stays the same and there’s no need for an internal floating piston and its associated lag as it compensates for the oil displacement when the shock is absorbing hits.

Trek claims the new Thru Shaft shocks increase both responsiveness and ground tracking. How? First off, Trek’s Re:aktiv shocks have a lot of low-speed compression damping (read: a stiff pedaling platform). But when a rear wheel hits bumps, the shock has to transition from resisting pedaling inputs (low-speed compression) to controlling faster hits and absorbing bumps (high-speed compression). 

Trek is claiming Thru Shaft tech allows for a faster transition between the low-speed and high-speed compression so the rear wheel stays better connected to the ground. The supposed improvement is that when you ride through rough terrain, the bike’s rear end responds quicker and maintains its speed instead of getting hung up and slowed down.

Trek claims its new shock responds to changes in terrain faster than any other shock on the market.

It’s not technically new

If you’ve been around mountain bikes for a good while, you may recall having seen something like this before. Manitou, White Brothers and RockShox offered similar technology in the past in both forks and shocks.

Trek claims the Thru Shaft shock responds to the ground faster than any other shock on the market
Dan Milner/Trek Bikes

The difference now is reliability. Thanks to vastly improved seals, components and manufacturing, Trek believes it now has a reliable solution.


On which bikes?

Trek has paired with both Fox and RockShox with the Thru Shaft tech. The trail-focused Fuel EX uses Fox Factory Float Evol shocks, the all-mountain Remedy and enduro Slash use RockShox Deluxe RT3 shocks.

  • Fuel EX 9.9
  • Remedy 9.8
  • Women’s Remedy 9.8
  • Slash 9.7
  • Slash 9.8
  • Framesets: Carbon Fuel EX, Carbon Remedy, Carbon Slash