We’ve been massively impressed with Focus’s super-controlled, alloy-framed, SRAM Eagle-equipped JAM trail bike this year. The carbon C SL shaves off a full 2kg to add blistering pace everywhere.
Focus JAM C SL specifications
Frame: Carbon fibre, 140mm (5.5in) travel
Fork: RockShox Pike RCT3 Solo Air Boost, 140mm (5.5in) travel
Shock: RockShox Monarch RT
Drivetrain: SRAM X01 Eagle (1×12)
Wheelset: DT Swiss XM 1501 Spline One 30mm Boost wheels
Tyres: Continental Mountain King II ProTection 27.5×2.4in
Brakes: SRAM Guide Ultimate, 180/160mm rotors
Handlebar: Concept CPX, 740mm
Stem: Concept, 70mm
Seatpost: RockShox Reverb 125mm dropper
Saddle: fi’zi:k Tundra M3
Weight: 11.8kg (26.01lb), large size without pedals
Focus JAM C SL frame
Not only is the full-carbon frame light, it’s loaded with neat features. Internal control routing is integrated into one side of the faceted head tube, and a ‘cobra head’ swelling of the top tube helps ensure front-end accuracy.
The front mech mounts onto the single-piece swingarm, so there’s no trace of it on the mainframe of this single-ring model. Focus’s ‘rocker link within a rocker link’ FOLD suspension puts the shock low and central for optimum handling, which leaves room for a bottle. The press-fit bottom bracket probably won’t last as long as a screw-in one, but the 30mm axle adds stiffness and there’s plenty of mud space in the Boost-width back end.
Focus JAM C SL kit
As a 2017 bike, the Jam C SL misses out on RockShox’s new Pike fork and Deluxe shock, but the current Pike and Monarch do a cracking job anyway. SRAM’s X01 Eagle drivetrain trades a few extra grams over XX1 Eagle for a more trail-proof rear mech, with no compromise of its ultra-wide range.
The Guide Ultimate brakes are aptly named, the 30mm DT Swiss XM 1501s are some of our favourite alloy trail wheels and the carbon-railed fi’zi:k saddle is a beauty. It deserves a faster rear tyre than the Continental Mountain King fitted, but that’s an easy fix.
The gear cable and rear brake and dropper post hoses all enter the frame on the non-drive side Mick Kirkman / Immediate Media
Focus JAM C SL ride impression
On first impressions, the 740mm bar, 455mm reach (large) and 67-degree head angle put the JAM into the ‘sorted all-rounder’ rather than ‘gonzo radical’ category (if that’s what you’re after, look to Focus’s SAM instead).
Deliberate flex in the ‘Guidelink’ that connects the back end means immediate power snap isn’t as sharp as on the stiffest bikes in its category if you’re wrestling a big gear out of the saddle too. But as soon as you get stuck into the trail, the JAM keeps on delivering more the harder you push it.
The FOLD linkage is simply outstanding – super-plush off the top for incredible traction, then becoming increasingly progressive for hard-driving cornering support and uninterrupted pedal-through or braking.
Harder or heavier riders may want to add a couple of volume spacers, but otherwise the combination of pedalling efficiency, slap-proof speed sustain and traction is brilliant.
Front wheel precision is excellent Mick Kirkman / Immediate Media
Front-wheel precision is excellent too, while that engineered flex in the rear sticks the back tyre down through the messiest rock or root sections that’ll send most bikes sideways.
The sub-12kg weight is a play-multiplying joy whenever you need to pop the bike up and over trouble, flare a hip or flick-flack a boulder chicane. It also makes your legs feel amazing when the trail points upwards – whether that’s for a 10-second burst or a 10-minute haul.
Ample traction and the ability to blend cross-country efficiency with serious confidence on technical trails mean the Focus smashes the ‘aggro all-rounder’ promise that so many bikes claim but few can actually deliver.
Focus JAM C SL early verdict
Brilliant ‘attack the whole hill’ all-rounder, with sorted handling and suspension.