Mach 4 SL Carbon Team XTR Live Valve Complete Bike
Cross-country riding calls for a whole different science from the traditional all-mountain machines we see dominating the marketplace these days. Instead of the long-low-slack trend that makes your ride feel akin to a Clydesdale, you need a speed machine built to operate with the thrust of a rocket ship fighting its way against gravity, beyond the atmosphere, and out into orbit. And so it takes a careful eye, keen attention to detail, and a different approach to build a beast like Pivot's all-new Mach 4 SL Carbon Team XTR Live Valve Complete Bike. This race-ready steed spins forward with progressive XC geometry that's roots combine the coveted Mach 4 and Mach 429 SL, and a sharp carbon layup that drops a whopping 300-grams off of the previous 429 SL's already feathery stature. But don't let this lightweight demeanor fool you — with steep geometry, 29-inch wagon wheels, and a new vertical shock layout, this space ship is ready to take flight up climbs, and soar down slick roots and chunky rock gardens while you charge your way to the front of the pack. And you don't have to just take our word for it, the bike is already making an immediate splash. How immediate? Woodruff racked up a Short-Track win within 24-hours of its launch, giving us sound proof that its built for speed.
As we've seen throughout the bike industry, the Mach 4 SL takes on the popular trend of longer-slacker, but doesn't go overboard into Trail territory, pulling the head tube out to just 67.5-degrees (paired with a 120mm fork). Compared to the previous 429 SL's 69.3-degree head angle, the Mach 4 SL's head tube will lend the slacker angle to a bit more stability on descents, so you can take on steeper drops, and chunkier rock gardens without your bike feeling noodly under pressure. But this is a cross-country machine after all, and with pedaling being top priority, Pivot's engineers make things steeper in the hind-quarters, moving to a prime perch for power at 73-and-a-half degrees — ideal for speedy power transfers, and staying forward when you're out of the saddle and mashing up steeps.
Speaking of pedaling platform — if you're familiar with Pivot's Mach 4 and 429 SL, you may be looking at the rear triangle with a puzzled gaze, as its shock layout shifts tremendously. While the Mach 4 SL still carries on with the coveted DW-link, Pivot's designers opt for a new vertical shock layout. This allows a more compact frame design that uses less material in order to shed weight, and improved integration for Fox Live Valve (we'll get more into Live Valve later). This new shock layout offers 4-inches of supple suspension, ideal for gobbling up variable trail terrain, and quieting harsh chatter on the straightaways. Much like DW-link applications you've seen before, the vertical layout still offers phenomenal small-bump compliance, keeping your tires glued to the trail for traction control as you soar up climbs, and a plush mid-stroke to take up the impact when you thought you could turn those two rollers into a double, but ended up taking things a little too far, and landing in the flats.
While the new shock is undoubtedly the highlight of the 4 SL's linkage, it's worth noting that it also affords space for a full sized water bottle (even in size extra-small, or two on the extra-large frame), and creates clearance for improved stand-over height, enabling size extra-small to accommodate riders as small as four-foot-ten, with a stand-over even lower than the 27.5-inch Mach 4 of prior seasons.
Pivot employs the XTR Team build with some of its favorite cherry-picked components to put together this rocket ship, including Shimano's latest-and-greatest XTR 12-Speed groupset that stretches beyond the competition, and offers you a gear for absolutely any terrain that might unfold in front of you. A lofty 11 - 51-tooth cassette accommodates sprints for the finish line when every watt matters, and offers a sense of relief when you're pointing it up intensely steep climbs that challenge your sanity. DT Swiss' carbon XRC 1200 hoops keep you rolling quickly, while a 36-tooth star-ratchet Spline hub offers near instant engagement for quick propulsion. To keep a good thing going, Fox's Factory suspension takes care of rowdy terrain, soaking up chunder with buttery-smooth Kashima-coated stanchions — and takes things up a notch with Live Valve integration.
Fox's Live Valve suspension brings electronics in to play, with technology that's been around in automotive racing for years, but has largely remained a foreign concept in mountain biking. To quiet the skeptics, Fox spent three years testing and developing Live Valve before it's launch, making sure reliability and performance were on target. The Live Valve system uses accelerometers on both the fork and the rear triangle to sense impacts and changes in the trail gradient, with a microprocessor (Fox calls it the Controller) mounted near the rear shock, housing a third accelerometer and a rechargeable battery. Using these sensors, the Controller measures terrain at a rate of 1000-times per second, and activates solenoid valves in the fork and shock that open in just three milliseconds, going from firm pedaling platform, to wide open plushness almost instantaneously.
This directly benefits cross-country riding, as it defaults the solenoid valves to the closed position, the equivalent of running your fork and shock in the firm mode, so you get the most out of every pedal stroke. When the system senses an impact, it opens the valves to allow smoother suspension action, improving traction, bump absorption, and overall ride quality. After a preset timer, the valves return to the closed position to regain pedaling efficiency. Each bump resets the timer, so when you're charging through rock gardens, or sustained sections of rough trail, the suspension stays in the open position to better mitigate impacts. The accelerometers also sense when you're going downhill, so if the bike is angled more than 6-degrees downward, both the fork and the shock remain open. When climbing, the Controller will open whichever suspension component feels the impact, and then return to the firm position immediately afterwards, unless another impact is sensed. For that trails, an impact opens both the fork and rear shock, with a delayed timer to account for successive impacts, but not so long to cause the bike to wallow in its travel when you start hammering hard. Should you go airborne, the system opens both the fork and shock to absorb your landing, returning to normal once again when the bike is rolling smoothly.
Fox claims that you can get around 16-to-20-hours of active ride time from a single charge on the Live Valve system, but if you run out of battery while riding the system opens your valves, so you can use all of your travel without a harsh ride. It's important to note that Live Valve only affects the low-speed compression circuit, changing the overall stiffness of your suspension. Rebound settings and air pressures aren't impacted, so you'll want to set your sag and baseline settings in the same manner as a normal air suspension. And if you're skeptical about the Live Valve, or think you might not want to ride with it every day, there's always the option of shutting off the system entirely, rendering your suspension the same as a standard setup.
- Pivot takes XC seriously with its new rocket ship ride
- Steep seat tube angle keeps you perched for the attack
- Take on chunky terrain, and power back to the top with moderate head tube
- Vertical shock layout improves stand-over height, water bottle clearance
- New frame design sheds 300-grams over previous 429 SL
- Fox Live Valve electronically adjusts compression in real time
- Live Valve switches between firm pedaling and open plushness in 3 milliseconds
- Lightweight carbon frame offers stiff control, and a 10-year warranty
- Kit includes DT carbon wheels, and Shimano's new XTR 12-speed drivetrain for lightweight, reliable performance