PROCALIBER TREK 8
£1,500 Unique hinged frame gives trail crossover potential
The 2018 Procaliber 6 and 8 are the first aluminium MTBs to get Trek’s unique ‘scissor frame’ IsoSpeed technology. The sprung effect is more noticeable in the car park than on the trail though, where the weight and need for faster wheels is more obvious.
The frame
The Procaliber is a bike of two halves. Trek’s big, chess-castle-shaped ‘E2’ head tube butts onto a broad, flat, rectangular top tube, which flattens even further by the time it reaches the seat tube. It then splits into two retro-looking snaked seatstays. But there’s nothing retro about the way they connect to the seat tube. Instead of being held in place by a fixed weld, they’re attached via a pivot. This means the seat tube – which flattens in the middle, then broadens like a paddle above the press-fit BB – can bow back and forth under seatpost loads.
There’s a cable exit port to back up the dropper post compatibility of the 31.6mm seat tube. A side-swing front mech sits on a fin sprouting from its base, above the broad press-fit BB. The wide, rectangular down tube has neat cable-insert blocks for the internal routing, and the brake hose sits externally for easy servicing. Relatively slim ovalto-square chainstays end at a camsecured Boost (148mm) axle. There are mounts for two bottle cages.
The kit
Even with the IsoSpeed technology, the fact that the frame is aluminium rather than carbon liberates a lot more cash for equipment. That translates to the latest Race Face Next R carbon cranks and a composite seatpost too. The Shimano SLX/XT mix is the latest 11-speed version, with a clutch on the rear mech to keep it quiet.
RockShox’s 2018 Reba has an updated chassis, with a cutaway section on the lower legs to save weight, and a remote lockout. It also uses a 110mm Boost axle to match the back end. The rear hub boasts 54-point engagement for fast pickup, and the low-tread Bontrager XR2 tyres are the top-spec, 120tpi ‘Team Issue’ version. Bonty’s Duster Elite rims come with tubeless sealing strips, so you just need to add valves.
The ride
While pick-up is rapid compared to the Shimano-hubbed bikes here, the Trek feels more ‘diesel’ than ‘turbo’ in terms of acceleration. Wheel weight is relatively high, and it’s the heaviest bike on test. Most significantly, the tyres are the grippiest here, which affects rolling speed to the point where we had to double check the
brakes weren’t rubbing. They also feel firmer at a given pressure than the Schwalbe and Specialized tyres.
On the plus side, the tougher feel means you can run them at lower pressures to offset the stiffness without worrying about pinch flats. They’re also the only tyres we could push reasonably hard in wet, woodsy conditions, which helped us exploit the smooth and accurate feel of the front end. Switching to faster, lighter wheels let the Procal’ suck in the turbocharged breaths it needed to and proved that it’s definitely not a soft, wattage-eating frame.
That also plays the other way. If you’re looking for a miraculously smooth in-saddle experience from the IsoSpeed decoupler, you’re going to be disappointed. While you can see the system working if you thump on the saddle, the Trek actually feels firmer in the seat than the KTM and, particularly, the Spesh. There’s no doubt that the technology does take the edge off bigger lumps though. This is crucial for race situations, because it lets you keep the power on hard through blockier terrain more easily than a conventional frame with similar power delivery.
If you’re after small-bump salvation for your spine, you’ll need to find that through lowering the tyre pressures. The fact this can be done without too many puncture worries, combined with the ability to fit a dropper post, gives the Procaliber significantly more rowdy terrain potential than the other bikes here. www.trekbikes.com