Surly’s Karate Monkey hardtail was one of the first widely available 29ers. Can a revamp keep this iconic big-wheeler competitive in the ‘eclectic yet economical’ category?
Veteran workhorse gets more versatile
Surly has used its double-butted ‘Natch’ chromoly steel tubeset to build ultra-tough workhorse bikes for years. If you want a frame that can take an implausible amount of punishment on home trails or riding round the world and shrug it off smoothly, then the Karate Monkey is ideal.
Despite reinforcing gussets on the top and head tubes plus a small triangulating reinforcing pipe for the seat tube, it’s not massively heavy. That means you’re not going to rupture your own gusset if you have to carry it when the trail gives up or the gears run out.
While the Karate Monkey has spent most of its history as a fully rigid singlespeed bike (still available both in complete builds or as a frame-and-fork setup) the new Ops version sports Surly’s ‘Modular Dropout System’, which lets you choose between horizontal (singlespeed), vertical (QR) or 142x12mm (found here) dropouts.
Bolted mounts for a rear mudguard and pannier rack tick the workday utility boxes, and a 44mm head tube makes it tapered fork steerer-compatible. The S-bent seat tube limits how far you can drop the seatpost on steep or rough terrain dramatically though, and the 27.2mm diameter restricts choice if you want to upgrade to a dropper post further down the line.
The Karate Monkey's S-bent seat tube allows big clearances within a reasonable length rear end but limits how far you can drop the saddle
With a kit list that’s all about smooth durability it’s no surprise to see a smooth-stroking, tapered-top Fox 32 Float fork with 100mm (3.9in) of travel heading up the spec. A 15mm front axle matches the thru-axle out back, and there are Centerlock rotors on the durable and user serviceable but heavy Shimano Deore hubs. DT Swiss Champion spokes are a high-quality bonus and the Alex XD rims are proven hoops.
Shimano’s Deore groupset also takes care of the 2x10 transmission and the M615 brakes, which give good feel and control – something that's immediately welcome when conditions get sketchy.
The wide (750mm), flat Surly bar gives enhanced steering leverage and the long (90mm) stem adds steadiness to the steep 72-degree steering angle. The low-knob Maxxis Ardent tyres let you brake and drive a lot harder than you might expect from their fast-rolling tread.
Their massive 2.4in volume (the “Fatties fit fine” script on the Surly’s chainstays is correct) and the generously padded Velo saddle add extra smoothness to the Karate Monkey.
It’s clear straight away that there’s not just a fat saddle and tyres between you and the trail, but a seriously smooth, shock absorbing frame in classic steel style. Even with a rock-proof 30psi in the 2.4in Ardents there’s less clatter and fewer sharp-edged shocks getting through to your shorts than on some more aggressively damped full-suspension bikes on smaller stutter bump/root infested trails.
That immediately makes the Karate Monkey a relaxing and low-fatigue way to spend time off-road, and the longer you ride the Surly, the more friendly and forgiving it feels.
The supple fork and skinny double-butted pipework (the top tube is 28mm in diameter and the down tube 34mm) combine with the extra-large 29erwheels to shrug off speed-killing bumps and keep momentum high. The compliance in the frame also keeps the Ardents stuck to the ground better than you’d expect whether you’re cornering or putting the power down, and it means you’re less likely to get knocked off your pedal rhythm by rut or rock impacts too. The high bottom bracket also means less chance of crank contact over sections of broken ground.
The Surly Karate Monkey's semi-clearcoat paint finish leaves the frame's welding details and heat marks visible
While traction and uninterrupted tempo pedalling are definitely a strongpoint of the Surly, direct power transfer isn’t. The same flex that soaks up bumps also delays power delivery slightly, so it surges smoothly rather than stabbing forwards when you give it full gas. That skinny top tube means any heaving of the big bar will twist the frame noticeably rather than creating maximum torque at the rear wheel too.
While most of the extra weight of the hefty hoops is in the hubs where it matters least, the big diameter and big tyres don’t do much for acceleration either. The steep head angle makes the front wheel feel light and easy to twist into corners, and the short stays and wheelbase make it feel comparatively nimble for a 29er on tight trails.
There’s no muscle in the frame to push power lines through rough corners or give pinpoint wheel placement though, so it’s best to let the Karate Monkey find its own surefootedly supple way through trouble rather than trying to stick rigidly to specific lines.