TESTED: KTM SCARP SONIC

It’s been eight years since we last tested a KTM. Eight years! Back then 26-inch wheels and triple chainrings were the norm and hydraulic disc brakes were just starting to appear on mid-range bikes. Mountain biking has changed significantly in that time but KTM has clearly stayed with the front pack of better-known global brands.

By the TREADmtb Testers

Photos: Dino Lloyd

THE BIKE

The new importer of KTM bicycles in South Africa, More Cycle, didn’t mess around and made their top-of-the-range XC/Marathon bike available for a few weeks for us to get intimate with. The Scarp Sonic has a full carbon frame with Boost width rear stays (and fork). KTM uses its Straight-Line-Link, a single-pivot rear suspension design, with a carbon rocker arm, high single pivot and flexy stays. So, with no rear-stay pivot, the chainstays are oversized, while the seatstays are super thin (similar to the design style of the new Specialized Epic and Cannondale Scalpel).

The suspension design is incredibly neat. It’s almost as if the engineers have tried to make the rear shock as minimalist as possible.

The high-performance carbon layup has been reworked to give the frame (with hardware) a claimed weight of 1700g (Medium), which is very similar to the SCOTT Spark RC.

There’s 90mm of Kashima-coated rear travel via a Fox Factory Float tuned shock, internal cable routing and provision for two bottles inside the frame (downtube and seattube). The fork is Fox’s super-light Factory Float with stepcast lowers offering 100mm of Kashima coated remote-adjustable travel.

With a 70.0 degree headtube, the geometry isn’t as relaxed as the likes of the new generation XC/Marathon bikes; but as we pointed out recently in the Momsen VIPA 2 review – Tested: Momsen Vipa 2, most South Africans don’t tackle the gnarly, steep descents as seen on World Cup courses, so a relaxed geometry isn’t necessarily a priority.

The drivetrain is SRAM’s XX1 Eagle 1×12 and the brakes Shimano XTR hydraulic disc with 160mm Ice-Tec rotors. The bars, seatpost and stem are all Ritchey Superlogic Carbon and the saddle is Selle Italia’s SRC with carbon rails. The wheelset is DT Swiss XRC, with carbon rims.

Top-end everything! No wonder it feels so light…

THE RIDE

It’s hard to say which made a bigger first impression on us – the bold, beautiful look of the Scarp Sonic, or it’s light weight. At Cycle Lab, where we first saw it, there was a sign on the bike that said “9.5kg – lightest full suspension bike in the store”.

That is certainly light for a full-suspension bike and we found ourselves doing the in-store bike lift a few times just to confirm its featheriness.

The tyres on the bike in the store were Schwalbe Thunder Burt, which we know are very light with thin sidewalls, so we asked for a Maxxis Ikon on the rear and an Ardent upfront. Yes, this adds some weight, but it also adds confidence for our testers. With the Maxxis rubber fitted and a tubeless conversion, the scale showed 10.05kg. Still damn light!

The first ride is always used to fine-tune the set-up and suspension. And in the case of a brand-new bike such as this one, bed in the brakes. It’s not normally a ride where we blast our familiar Strava segments, but it just seemed like the right thing to do on the Scarp Sonic. It’s light and nimble and it wants to be ridden fast. And it yielded a string of PRs as well as couple of KOMs, which were a nice surprise. Each test rider reported the same thing – Strava PRs on their orientation/set-up ride.

We agreed that we’ve never felt this fast on a climb on any bike before. The Scarp Sonic is an incredibly responsive ascender. And our segment times confirmed this. It’s very at home on more predictable surface ascents, both short and long and steep and steady… However, it’s not quite as nimble on very rough surface climbs.

Descending was good, but we have definitely felt more stable on steep, rough descents before. We put it down to a combination of the geometry, the lightness of the bike (it tends to bounce around a bit more than you’d expect) and the narrowish 680mm handlebar.

Cornering was very good. We find that on bikes with more relaxed headtube angles we need to lean further forward than normal on fast, flat turns. But on the KTM, with its more, let’s call it ‘neutral’ geometry, we felt very confident straight away in any turn. Even at that light weight, the bike felt balanced when attacking corners, but the acceleration out of turns really was noticeable, a key factor for any bike in this category.

Remote suspension control is an integral part of a high-performance race bike and it’s very important that this works as it’s intended to, which sometimes isn’t the case… The front and rear suspension on the Scarp Sonic is simultaneously adjustable via Fox’s new remote dual lever, a small, comfortable, easy-to-adjust handlebar-mounted system that sits neatly where a front gear shifter normally would, beneath the left side of the handlebar. Typical of the race setup it offers two settings (Open and Locked) and it worked well for the entire four weeks we tested the bike. A first for us with a Fox remote lever, job well done.

THE VERDICT

The Scarp Sonic is KTM’s the top-of-the-range XC/Marathon race bike. It is unashamedly light and fast – a pure racing thoroughbred in every respect. It also performs best when ridden by a skilled, conditioned rider as it requires a high level of rider input on rough surfaces, both ascending and descending. But this comes with the territory with a lightweight bike with minimalist rear suspension design.

It’s probably too light for anyone that’s not a super-competitive, well-conditioned rider as it does require some finesse to take it to its limits. It also only comes in three sizes, 17-inch, 19-inch and 21-inch, nothing for very short or very tall riders. As it is there is a weight limit sticker at Kg110, sorry buffaloes.

All our testers said they’d swap out the 680mm bars for 720mm, but other than that we were super impressed by the Scarp Sonic and all suffered separation anxiety when the orange and black ‘Strava Slayer’ was returned.