Almost by definition, bikes come with compromises. A stiffer bike might mean more responsive, but it’ll cost you comfort. A slacker one is often more fun on descents, but likely a pain climbing uphill. A big suspension allows you to bulldoze over rocks, but you’ll be stuck moving at the speed of a bulldozer all day. Despite what marketing gurus want you to believe, no two-wheeled steed can do it all; there’s always a give-and-take.
Short travel cross-country (XC) bikes — everything from 100mm to 120mm — are often the biggest culprits of this type of hyperbole. Tucked between trail bikes designed for technical singletrack and old-school hardtails made for flow trails, they are booming in popularity thanks in part to spin doctors who position them as one-bike-quiver-killers, able to handle anything. But very rarely is that true.
Pivot Cycles, on the other hand, stuck to their vision: making a rocket ship. When they launched the first Mach 4 SL in 2019, their full suspension lineup was missing one thing: a high end XC bike. Pivot claimed the Mach 4 SL could take podiums, but the results were a mixed bag. It was lighter and faster than its big siblings, but not otherworldly efficient. The new version remedies this, fully realizing their original vision.
The original Mach 4 SL took 300 grams off its predecessor, the Mach 429SL; this new bike follows suit, carving 300 more grams off. A size small World Cup build now weighs under 23 pounds including a dropper seatpost, putting it near the top of XC race bikes. Combine with a responsive feel, minimalistic design, and capable front and rear suspension, and you get a near perfect XC bike – a blend of speed, efficiency, and enough performance to hunt down podiums.
While Pivot’s main priority was making a rocket, the Mach 4 SL doesn’t fall too far off the pace in performance metrics like suspension, stiffness, or handling, either. The frame was completely redesigned, with a lengthened and slackened geometry and a revised DW-link suspension (which Pivot has used since its inception), helping maintain confidence on technical trails. Overall, it’s incredibly fast — and fun to ride.
The Pivot Mach 4 SL, at a glance:
- Fits 100mm or 120mm fork
- 29” wheels only, up to 2.40” wide
- 31.6mm seatpost size
- Only 1x drivetrain compatible
- 36-tooth chainring max
- Flip-chip quickly adjusts suspension
- 5 frames sizes fits riders 4’10” to 6’7”
The Pivot Mach 4 SL: What We Think
This is an incredibly fast and fun bike — if you can get past the price tag. The basic build starts at $6,199 and goes up to $11,599. While the top end is in line with competitors, I would like to see a lower budget model offered, but perhaps that’s down the road. Overall, it’s a big leap forward from its predecessor of four years ago and should hold up against most other bikes in the XC category.
The best part about the Mach 4 SL is what it’s not. While many short travel bikes these days try to be as progressive as possible, Pivot went the other way. They leaned into speed, designing a race bike that’s snappy and efficient, while tweaking the frame to keep it fun to ride on most trails. I tested it for three weeks across a variety of terrain around Bend, Oregon, and came away highly impressed.
The Mach 4 SL is faster than previous Pivots
The Mach 4 SL eats miles, corners easily, and stays remarkably high in its travel, keeping your energy going forward. The rear shock’s rocker link is trimmed down and the frame is sleek, saving noticeable weight. The seat angle is steepened, helping the bike climb faster, a knock on the old version. The head angle is relaxed and the reach and wheelbase are longer, which provides a stable ride. The handling and stiffness are on par with — or perhaps slightly better than — other XC bikes I’ve tested.
The real story is how much Pivot was able to trim down the frame, to make the bike faster. They claim “no stone was left unturned in the quest to shave weight,” and after testing I’m inclined to believe them. The Mach 4 SL is made to go as fast as your lungs and legs allow. The secret is their proprietary Hollow Core carbon fiber molding technology, which reduces the tube size and reinforcement areas. The vertical shock design lowers the center of gravity and standover height, and allows two water bottles inside the frame.
The tires are a little too big
This may sound nit-picky, but the demo bike that Pivot shipped had 2.4” tires, which is a whole lot of rubber. I rarely run trail bikes with tires that big, because big tires are slow and sluggish, even if they do make for a smoother ride. After swapping them out for more standard 2.5” XC tires, I had a better experience on the bike. Perhaps I’ll swap them back for bikepacking trips or sandy trails.
Pivot's newest bike could offer a little more comfort
The Mach 4 SL gets a bit of a pass on comfort and compliance, but it’s certainly not best in class. At times the bike can feel stiff and uncomfortable, a common flaw in the fastest end of the mountain bike market, and Pivot may look to improve this in the future. The Mach 4 SL, despite being light and snappy, is still average while climbing and in tight corners. With a longer wheelbase and a slacker frame, it’s a sacrifice they knowingly make to keep the bike more competent in a variety of terrain.
The Mach 4 SL has plenty of travel
The bike I tested had enough travel– 120mm front, 115mm rear– to keep up on most descents with bigger bikes. I even set a few personal KOMs on longer, rolling loops, showing that pros can win gold while riding it, too. It feels similar to the old version in regards to suspension and stability– an impressive effort by Pivot to not sacrifice ride quality while investing all-out in speed. An adjustable flip chip bumps rear travel from 106 to 115, which makes a big difference on jumps and chunky bits, too.
If you’re looking for a top finish at your next race, I’d highly recommend the Mach 4 SL. It’s light and efficient, and has improved how it handles and climbs, making true on the promise of being a blue chip race bike. Even with a slacker and longer frame, the Mach 4 SL is more responsive than the past version, almost as if the bike is begging you to hammer on the pedals. The speed almost got me in trouble more than once — like getting in a sports car after a decade driving a Subaru.