US brand’s high-end hardtail says farewell to IsoSpeed
Trek’s new Procaliber is the brand’s top-level hardtail mountain bike aimed at cross-country racers looking to take advantage of a rigid rear end.
In its third generation, the Procaliber has had its fork travel upped from 100mm to 120mm and ditches the IsoSpeed design for a new IsoBow compliance system, making it lighter and simpler than before.
We have the top-of-the-range, £4,250 Procaliber 9.7 AXS Gen 3 in for testing with dormant XC domineer Jack Luke looking forward to putting it through its paces.
But before we get the bike out on the trails, let’s take a closer look at some of the details.
Reframed compliance
A fresh frame design sees the departure of Trek’s IsoSpeed compliance system, which used a junction decoupler at the seat tube and seatstays to reduce vibrations from the trail.
The previous design relied on a pivot, which not only required maintenance but also added weight.
Trek says it has addressed these concerns with the new IsoBow compliance system.
The new design sees the seatstays extended beyond the seat tube, allowing for increased vertical compliance while maintaining pedalling efficiency.
Trek says its sponsored athletes can’t tell the difference between the IsoSpeed and IsoBow in a blind test.
It’s not a completely revolutionary solution, with similar systems used on gravel bikes, such as GT’s more recent Triple Triangle Design seen on the Grade, designed to improve compliance.
Lapierre uses a similar design to smooth out trail chatter on its Prorace CF9 9.9.
Elsewhere, the bike features a floating brake mount, similar to the full-suspension Supercaliber, which isolates braking forces from the seatstay flex to improve compliance and provide better braking consistency over bumps.
Top-echelon carbon
The frame of this Procaliber is made from Trek’s high-level OCLV Mountain Carbon, which is claimed to be put through the most extensive research and testing in the industry.
Trek has bucked the trend by not giving its lightweight cross-country bike internal headset cable routing, instead routing cables through the sides of the head tube.
Depending on where you stand on internal headset routing, there’s no doubt this will make mid-season bearing replacement less of a chore.
All these changes have resulted in a frame that is on average 150g lighter than the previous model through the sizes.
The frame is finished with a down tube protector and a chainstay protector, both of which are made from rubberised plastic to reduce amplification on impact.
Slack and steep?
The Procaliber comes in five sizes: S, M, ML, L and XL, with reach measurements ranging from 405mm to 500mm.
Overall reach has increased, with a size large growing from 450mm to 460mm
Trek has shaved 1.8 degrees off the head angle, which now sits at a more aggressive 67 degrees compared to the previous 68.8 degrees.
The effective seat tube angle has steepened from 73.8 degrees to 74.3 degrees in order to maintain an efficient pedalling position.
Trek says these alterations have made the bike calmer when descending, while increasing confidence at higher speeds.
Top-spec
This Procaliber 9.7 model is said to be specced with upgrades that make a difference, and it looks to balance budget and boujee very well.
The bike has a 120mm RockShox SID fork with a Rush RL damper and lockout remote that should make smooth climbs easier.
Bontrager’s Kovee Elite 30 wheels are made from the same OCLV Mountain Carbon as the frame.
These come booted in 29×2.4in Bontrager Sainte-Anne RSL XR tyres, enabling the bike to be run tubeless, although we’re using Pirelli Scorpion XC RC tyres.
Shifting and braking power is provided by SRAM, with the wireless GX Eagle AXS Transmission derailing the chain and Level Bronze four-Piston brakes grabbing 160mm and 180mm rotors.
Bontrager’s RSL Integrated handlebar is used for the cockpit, with sizes S, M and ML specced with a 70mm stem, the L with 80mm and the XL with 90mm.
In true cross-country style, the Chunky grips are provided by ESI in the hunt for weight savings.