‘Challenge the threshold’ is the concept under which Pivot’s new Mach 4 SL has been designed. It’s unashamedly an XC and marathon race platform, but to call it just a race bike is to do it a complete disservice as the new Mach 4 SL with its adjustable travel/progression is truly a genre crossing tour de force.

Need to know:

• All new full carbon 29in XC/Marathon/Downcountry platform
• Available in two travel versions where DW-Link suspension offers on-the-trail swappable travel from 95-103mm or 106-115mm depending on the shock stroke.
• Bikes are matched with either 100mm or 120mm travel forks
• Frame weight is reduced by up to 400g compared to previous Mach 4 SL
• 4 models plus frame only option for the UK, bikes start at £8,500

But before we get to the suspension, let’s talk weight. Because, in the world of XC racing, weight is still the number one priority.  As such, weight reduction over the incumbent Mach 4 SL was a key part of the development process. Pivot’s designers and engineers achieved their goal with a new carbon frame that’s 400 grams lighter than the old model – impressive, given that the outgoing Mach 4 SL wasn’t exactly on the portly side.

Now for the complicated part. The old bike had 100mm travel, but the new version comes in two opinions: one short travel XC race focussed version with a 100mm fork and 95mm or 103mm of rear travel. Then there’s the downcountry/marathon option with 106mm or 115mm rear travel and 120mm fork. Where both bikes share the same frame and it’s the shock stroke that changes.

The ability to adjust the travel on each option comes from the new forged aluminium upper rocker link, which now features flip chips to alter the leverage ratio of the suspension kinematics which changes the progression rate effectively allowing more or less travel to be achieved from the shock. It’s interesting to note that this feature does not alter the geometry of the frame at all.

Like all Pivot frames the bearing seats (frame, headset and bottom bracket) on the Mach 4 SL are machined directly into the carbon, which not only saves weight, but also provides far better tolerances than aluminum inserts, ensuring extended bearing life in all areas. Pivot does things differently with the cable routing too, forgoing the common tube-in-tube design, preferring open ports to save 30g per guide. This approach also provides better brake hose routing regardless of which side you route the hose – handy for us contrarian Brits. Interestingly there’s no Fox Live Valve routing or mounts on the new frame, which could indicate a switch to wireless or Pivot moving away from this technology.

What you can’t see by simply looking at the new frame is that each frame size benefits from a specific carbon layup, as tubing and frame stiffness requirements are not uniform across all five frame sizes. And it’s worth noting that even the XS size is specced with 29in wheels. There’s space in the compact frame for two bottles on the size medium and upwards, where the second bottle is mounted to triple bosses found under the top tube. Just don’t expect to fit two full size bottles though, unless you use the third mounting point under the down tube.

How it rides

From the first pedal stroke there’s no mistaking the Mach 4 SL for anything other than a Pivot. That DW-link suspension delivers such a recognisable ride feel that defines the entire range. Over a three day period concentrated mainly on the flowing, sandy and rocky trails around Cortez, Colorado I was able to test the more marathon/downcountry version in both travel settings and I came away impressed.

Pivot has worked hard to create a suspension kinematic that reflects the type of riding the Mach 4 SL has been designed for; namely riding fast and pedalling hard. It’s worth noting almost immediately that even though the Mach 4 SL came specced with a lockout for the rear shock it was rarely needed.

Unlike many XC race oriented bikes I’ve ridden, the Mach 4 SL presented none of the usual nervous handling traits that a lightweight machine can deliver. This is a bike you can jump on and within minutes it feels like you’ve ridden it for years. For me the 462mm reach of the large frame size, the bar width and stem length felt spot on and I was able to ride as fast and as hard as my abilities would allow.

Confidence is something the Mach 4 SL instills no matter the terrain. On rocky ledges and steep loose trails it rode like a bike with far more than 115mm of travel. This is backed up with the sensibly specced Fox 34 Step-Cast fork – now the racers favourite. In fact, the only thing I could fault in these situations was the 160mm rotor up front. For the speed the Mach 4 SL could generate I would have preferred a 180mm rotor, especially if I was riding UK trails. Even for XC racing I would prefer the larger rotor as it helps reduce fatigue and makes you faster.

Switching the flip chips in the linkage to the shorter travel setting had one of the most dramatic changes to a bike’s personality I have ever experienced. Gone was the easy living trail bike feel and in its place was a snarling XC race machine. The change in leverage rate really ramps up the progression and the change is instantaneously felt through the pedals. It’s also worth mentioning that the leverage rate in the initial part of the travel is unchanged, so there’s no need to adjust sag when switching between modes. Despite that, it feels like there is zero loss of power transfer in the short travel setting and even if the altitude was making me feel less than 100%, I was able to whip up gradients without as much effort.

In both travel modes the Mach 4 SL provides wickedly engaging handling. On the roller coaster trails of Phil’s World it reacted to inputs insanely fast and whipping it around corners and pushing the limits of the Maxxis Rekon Race tyres was some of the most fun I’ve had on an XC race bike in years. It also likes to take to the air and the front end pops up faster than most other bikes in its class. This light feeling front end did cause a few issues on steep techy climbs, making it hard to keep on line, but after dropping the stem by 15mm it felt really balanced, without killing the fun factor.

With all the updates, Pivot has been able to achieve a lightweight XC race bike that will still have riders who live permanently outside of the race tape grinning from ear to ear. And for riders who do both, the travel adjust feature ensures you will always be on the right bike regardless of whether your ride starts with a gun or at the trailhead.

So for riders looking for that elusive short travel ‘one-bike quiver’ the Mach 4 SL comes close to being perfect as it can effortlessly transition between XCO races, grueling ultra-distance marathons, or chasing your mates on trail center loops.

Looking for the best cross-country mountain bike you can lay your hands on? We’ve done all the testing to make your job so much easier. And don’t forget to pop on the best mountain bike helmet too – after all, you’ve only got one head.