Flexing Muscles, Not Stays: A Pivot Mach 4 SL Review – Ryan LaBar | The Radavist | A group of individuals who share a love of cycling and the outdoors.

In the world of cross-country bikes, there’s a trend of pivots disappearing. Not the brand “Pivot,” but the actual pivots. Specialized heaved the Horst Link, Trek axed its ABP, and Santa Cruz vetoed the VPP. The idea is, at around 100-millimeters or so of travel, weight savings and stiffness take precedence over kinematics. But Pivot (the brand) stuck to their guns for the recently revamped Mach 4 SL cross-country bike. They tweaked their DW Link and refined their carbon layup, claiming better ride quality and a half-pound lighter frame. They sent their flagship build to Ryan LaBar in northern Michigan, and it seems he’s putting this bike on a pedestal, without even needing to put it on a podium.

The Mach 4 SL is one of those bikes that we thought wouldn’t need another iteration until the next derailleur-hanger standard takes over in 2032. But to my surprise, Pivot had things they wanted to change. The most immediately noticeable difference between Pivot’s new and old full suspension race steed is the geometry refinement. The Mach 4’s numbers got updated in the ways we’re almost tired of hearing about: The reach was extended by 15 millimeters and the effective seat tube angle was steepened to 74.7 degrees (measured at the horizontal intersection from top of head tube). The head angle got slackened by just under a degree to bring it to 66.7 with a 120-millimeter fork. Or, you can opt for a 100mm fork, steepening those angles by 1.3 degrees. A few of the other numbers got tweaked too, but only by a few millimeters.

Pivot also found a way to further improve its take on the short-travel DW link. This year’s model is slightly more progressive and tweaks the anti-squat to improve pedaling efficiency. Also new is the flip-chip in the rear, which changes the Mach 4’s rear-shock travel without affecting geometry. The travel can be set to 106 millimeters or 115 millimeters, with the shock I tested (the World Cup builds get a different shock that reduces travel slightly).

What’s happening here is that the leverage ratio gets adjusted, effectively reducing the travel. There is also a minor effect on progressivity that makes it so you don’t need to adjust air pressure when flipping between travel modes. The shorter travel mode definitely has a firmer/racier feel and would be my choice for smoother terrain. I like riding rougher trails, and I’m well out of my college-aged aspirations of racing pro XC, so I spent the majority of my time on the Mach 4 in the 115-millimeter mode. The only number I could see some fault with is the max-tire size of 2.4 inches. While it’s rare, there are certain times I like to reach for higher volume tires—namely for big adventure rides.

The Details

Pivot is known as being a premium brand, and with that comes the expectation that no detail is overlooked. Even with high expectations, the overall refinement of the Mach 4 SL really impressed me. The integrated injection-molded chain-slap protectors fit the frame perfectly, and I was pleasantly surprised to see some real structure to that protector’s main section, with raised hollowed-out ridges to help keep the chain quiet and the frame from getting chipped up. Bonus points to the upper seat-stay protectors, and the vertical brace tubing. On a bike designed to be as light as possible, I was very happy to see Pivot understands the importance of protecting its customers’ investments.

The mud/dirt catcher covering the lower linkage was also very welcomed, as I found this to be a spot for mud/dirt to collect on sloppier rides. The cable and hose routing is also very tidy, and the frame has fully guided internal routing. Even the placement of the lockout cable is pleasantly unobtrusive. Honestly, I could go on, but I think this would get pretty boring: The long and short of it, it’s strikingly obvious that Pivot put a lot of thought and care into every inch of the Mach 4.

The Build

Brands love sending out their most high-end build for review. And my test bike was, indeed, most high-end, with SRAM’s XX SL Eagle Transmission drivetrain and Level Ultimate Stealth two-piston brakes. Pivot rarely strays from Fox suspension, so I got a Factory series Float in the rear and a FIT4-damped Stepcast 34 up front. I was surprised to see the rear shock mated to a RockShox TwistLoc lever, but if it works, it works. Pivot also decided to run a full-length dropper on this bike, which for me is a must-have. They could have saved some weight here, but opted to keep with the wireless theme and spec the RockShox Reverb AXS.

The wheels are Pivot-branded Reynolds Blacklabel rims mated to Industry Nine Hydra hubs. That’ll be $11,600.. Pivot doesn’t really do budget builds. The lowest-price build kit for the Mach 4 SL will still set you back $6,200. This build sees the same highly detailed frame. No aluminum rear triangle or lower-grade carbon to be found. But it is spec’d with a mixture of Shimano SLX and XT, and loses the carbon wheels and handlebars. Of course, I would still consider that a very race-ready, well curated build.

The Ride

Sitting just under 25 pounds on my scale, it’s no surprise that the Mach 4 SL scoots uphill with incredible ease. What was surprising, though, was just how the bike handled technical climbs. I take secret, often unhealthy pleasure in weird, rock-pocked, root-riddled climbs that toe the line of impossible to clean. And the Mach 4 is very much an enabler. The suspension is active enough to absorb square hits well. One of the Mach 4 SL’s buzzwordy features is its “position-sensitive anti-squat,” but even with Pivot’s marketing communications shut safely inside my laptop, I still felt it. Despite its moderate travel, this bike keeps its rear wheel dredging for traction when the power is put to the pedals. The geometry felt really well balanced for this as well: The front wheel was easy enough to lift and reposition, but didn’t feel too lofty or wandering, and the back end felt far enough behind me to stay stable, but provide ample traction in loose or slick sections. That said, Pivot is not on-board the size-specific chainstay train, running a middle-of-the-road 432mm rear-center across the board. I tested a size large, so your mileage may vary.

When the climbs smoothed, the suspension design rewards effort, becoming more efficient when the power’s put down. After the first handful of rides, I thought I’d conclude that the lockout was a bit useless, but as I spent more time aboard the Mach 4 SL, I became accustomed to instinctively using it, even if only while grinding fireroad climbs. It should definitely be noted that this newer version of the TwistLoc is much nicer than previous iterations, and I didn’t have any accidental lockouts, which was an ongoing issue I had with the older models.

Pointed the other direction, the Mach 4 SL is predictable and capable. The Fox 34 StepCast does a fine job keeping the front of the bike tracking true, and the suspension feels balanced and active. It allows this bike to shine on chundery descents where other race bikes often feel chattery and skittish.

The Mach 4 SL has a way of inspiring confidence on terrain it has no business being. When presented with multiple line choices, it almost felt as though I was being dared to take the A-line option over the B-line. By nature, this caused me to seek out trails I normally reserve for much beefier, longer-legged bikes. Some folks might be tempted to reach for the dreaded ‘down country’ descriptor for the Mach 4 SL, but I don’t feel that’s quite accurate: I haven’t found a down-country bike that can hold a candle to the Mach 4’s climbing prowess and overall pedalability. And, conversely, there are other bikes with similar travel numbers that sacrifice pedalability in favor of making descents more of a priority (and that’s ok). To that note, despite the gutsy confidence, the Mach 4 reminds you that it is a feather-light race machine on hard g-outs and successive big hits. One such reminder ended in me donating some skin to an old oak tree.

On less extreme descents—the ones this bike was actually built for—the suspension and updated geometry work in perfect harmony, finding a rare, smile-inducing balance of nimbleness and stability. For racers, this means you can either use the descents to recover for the next climb without losing any ground, or throw caution to the wind and use the descents to launch an offensive.

While mountain bikes, especially these days, are often judged solely by their climbing and descending capabilities, long-ride comfort shouldn’t be overlooked. If blasting up technical climbs is the Mach 4’s bread, and fast-flowing descents are its butter, all-day adventure rides are the ice cream for dessert. The overall fit of the bike felt, basically, perfect: not too stretched out, or overly upright, nor too far over the bars, or too planted on my butt. This body-position harmony, combined with the efficient yet active suspension, made it so that, even after hours in the saddle, I could still fervently attack both descents and climbs.

Putting It All Together

While it was built with the primary purpose of thoroughbred racing, the Pivot Mach 4 SL stands out as much more: It’s a bike that almost perfectly blends performance, versatility, and raw, grin-inducing glee. I can’t remember the last time I swung my leg over a cross-country bike that’s as fun to ride as the Mach 4 SL. And that’s true in scenarios where “fun” is usually the furthest thing from your mind. Like chasing podiums, or tearing your friends’ legs off on lunch rides, or spending the weekend munching miles on big back-country singletrack. Again, it doesn’t come cheap, but the details and performance that Pivot packed into the Mach 4 SL definitely make it something special.