Pivot updated its super XC race bike, the Mach 4 SL (previously known as the Mach 429 SL), in 2023 (read the full tech piece here), ushering in the third iteration of this unique off-road machine. In a nutshell, the newest model is 300-400g lighter (depending on size) than the previous version. It now includes a flip chip to adjust rear travel slightly. Giving riders four different travel options, all in one frame.
The Double Life of Pivot’s Mach 4 SL
The Pivot Mach 4 SL is a race bike, but it’s also a friendly cross-country machine. The updated geometry of the Mach 4 SL aims to achieve maximum climbing efficiency (it’s mountain biking, after all) and a well-rounded handling profile. The bike appeals to the aspiring (and real-life) professional mountain bikers of the world and the recreational rider looking to best their buddies on the local KOM.
Choose Your Weapon
Pivot offers different builds that lean into the various styles of racing and riding. There is a World Cup short travel build for those looking for maximum speed, with travel ranging from 95mm to 103mm.
For those looking for more modern cross country (as most of the world is), the Team, Pro, and Ride level build get 106mm or 115mm of travel. Riders can choose 100 or 120mm fork travel for their Mach 4 SL journey — further dialing in the specific use for this shred machine.
Pivot Mach 4 SL – Frame Details
Pivot’s Gen 3 Mach 4 SL showcases size-specific tuning for every frame size. That means Pivot employs unique carbon layups for each size to ensure the balance of stiffness and compliance, no matter what size you ride.
The bike’s aesthetics also tell a story—its smaller-diameter tubing and more compact front and rear triangles depart from the bulkier profiles seen on other Pivot mountain bikes.
Larger bottles! Every size fits a large water bottle in the main triangle, while sizes M-XL can hold two bottles. Pivot added two accessory bosses under the downtube and three under the top tube, giving riders plenty of gear mounts or storage options.
Why Flight Attendant?
If you’re going to release a race bike, you need to have the latest and greatest available. Right now, for most, that means Rock Shox Flight Attendant suspension. (You can read the tech details of the new FA Here). In a nutshell, the addition of Rock Shox Flight Attendant to the Pivot Mach 4 SL takes lots of cable clutter away from the cockpit and frees the rider from thinking… it’s also adjustable, programmable, slightly heavier, and requires more batteries.
However, for some (most), this update is worth the extra charging, and we tend to agree. It lets the rider concentrate on the trail and performance rather than suspension needs. As for its effect on the Pivot Mach 4 SL, the Flight Attendant puts a fine point on the bike’s performance in all cross-country needs.
Geometry – Pivot Mach SL4
Pivot’s revamped Mach 4 SL comes with two distinct fork options—100mm or 120mm travel—each bringing notable geometry differences to the table. Across the board, all models boast a slacker head angle, steeper seat tube angle, and longer reach compared to the previous generation. Opting for the 120mm fork gets you a trail-ready 66.7° head angle, while the 100mm version steepens things up to 68°. That extra steepness adds about 13mm of reach, giving riders the ability to fine-tune fit and handling depending on their preferences.
The seat tube angle follows suit, sitting at 74.7° with the 120mm fork and steepening to 76° with the 100mm spec. The chainstays, however, stay consistent across the board at 432mm, keeping the rear end snappy no matter the build.
Pivot’s sizing game is on point, too, with the Mach 4 SL offered in XS through XL frames. Pivot says this five-size lineup covers riders from 4’10” to 6’7″. That’s most, if not all, of the mountain biking world.
Full review ride Spec – Team XX SL Eagle Transmission Flight Attendant Kit
- Wheel Size: 29″
- Frame: Mach 4 SL
- Wheel Material: Carbon
- Sizes available: XS-XL, Medium tested
- Weight: 25.5 lbs.
- MSRP: $13,499
Suspension
- Rear Shock: Rock Shox SIDLuxe Ultimate Flight Attendant
- Fork: Rock Shox SID Ultimate Flight Attendant 29″, 44mm offset, 120mm
Drivetrain
- Rear Derailleur: Sram XX SL Eagle AXS 12-Speed
- Cassette: Sram XX SL 1299, 10-52t
- Shifter: Sram AXS Pod Ultimate Controller
- Crankset:
- Sram XX SL Eagle Power Meter DUB, 34t
- Handlebar:
- Phoenix Team Carbon – 760mm
- Stem: Phoenix Team XC/Trail – 40mm
- Seatpost:
- Rock Shox Reverb AXS: 125mm
- Saddle: Phoenix WTB World Cup Volt Carbon, Medium Width
- Wheels: Reynolds Blacklabel 309/289 XC with Industry Nine Hydra hubs (30mm F / 28mm R) Hub Spacing: 15×110 F / 12×148 R
- Tires:
- Front: Maxxis Rekon 29″ x 2.4″, 3C TR, EXO, 120 TPI
- Rear: Maxxis Rekon Race 29″ x 2.4″, TR, EXO, 120 TPI
- Brakes: Sram Level Ultimate Stealth, 2-piston
- Rotors:
- Front: Sram Centerline CenterLock – 180mm
- Rear: Sram Centerline CenterLock – 160mm
- Chain: Sram XX SL Eagle, 12-Speed Flat Top
Ride Review: Pivot Mach 4 SL Flight Attendant
When the Pivot Mach 4 SL arrived, it was in a smaller box than expected. When I started to unpack, I noted everything was packed to perfection and previously dialed in for my specs. Since this is my first review ride from Pivot, I didn’t know what to expect, but small details like the packing and attention to detail made me feel taken care of before ever stepping foot on the Mach 4 SL.
Building and setup were quick and pain-free. Everything went together without an issue, and parts were packed in a way that helped me flow though the build easily. The SRAM AXS and Flight Attendant bits were paired and worked well. I added them to my SRAM AXS app and ensured everything was running the most recent firmware. Beyond that, the bike was trail-ready from the box, all I needed to do was set fork, shock, and tire pressure.
On the trails
Before I hit the trails, I set up my suspension sag at 20% and let the Flight Attendant do its thing. Our review Mach 4 SL came with the 120mm SIDLuxe Ultimate Flight Attendant, a fork with which I’m familiar (at least the non-FA version). After the first ride (a super short trail exploratory one), I adjusted the bias slightly but was somewhat dialed from the stock setup. To learn more about the Flight Attendant setup – I suggest this basic setup guide from SRAM.
On the trails, the Flight Attendant shines. It’s not as fast to react as a cable-actuated lockout power by a rider, but it doesn’t forget (like me). The SidLuxe shock has three modes, open, pedal, and locked. Having the suspension float in and out of the pedal and full open mode while going all out is something I especially enjoyed. I wouldn’t have done this on my XC bike with a 3-position cable lockout. I tend to switch between fully locked and pedal, rarely fully open – that changed after more rides on the Mach 4 SL with FA.
It was liberating to free the part of my brain that was thinking about when to lock out and when not. I just rode and listened for the little servo sounds of the lock and open (you do hear it), knowing my suspension was doing its thing, and all I needed to worry about was the bike’s driving.
Maximal descending confidence
When you pair the Mach 4 SL updated geometry with a 120mm fork, the rider gets a unique boost of convince. The geometry changes slightly, and it’s more laid back for sure. But if that translates into a few seconds on the downhills, it’s worth it. The slightly higher position enabled me to push more on the chunky trail bits with still a great deal of confidence in the bike’s climbing ability. The shorter-than-usual-for-me stem (I usually ride an 80mm/-12) played into this, as did the 35mm clamp. This slightly tweaked spec and boost in stiffness paired well with the Mach 4 SL unifying mission to go fast at all costs.
Climbs Well Too
The Mach 4 SL balanced ascent is decent, accentuated by adding a Rock Shox Flight Attendant. The geometry of the bike and the steeper seat tube angle offer a great perch to pedal hard and feel like you’re over the bottom bracket getting leverage. While the suspension is cycling in and out of locked and pedal. The rider gets the best grip and ability to climb. As mentioned above, if I were on my bike, I would have been locked out most of the climb, only opening to pedal when it crested slightly. But now, after riding the Flight Attendant, I’m rethinking my approach.
Professional Spec
Everything (and I mean everything) on the Pivot Mach 4 SL is professional-spec. There is nothing on this bike that a professional rider would need to update. For me, the specs were right on, and I couldn’t ask for more (well, OK… one thing). Off the bat, you have a power meter, SRAM XX Transmission shifting, and SRAM Level Ultimate Stealth, 2-piston brakes.
The wheels are Pivot branded Reynolds Blacklabel 309/289 XC with Industry Nine Hydra hubs. The rims are varied, with a 30mm Front width and a 28mm Rear, and come wrapped in Maxxis Rekon and Rekon Race tires, just enough to race and get gnarly when needed.
The only thing I would change if pressed is the shifter buttons on the AXS Transmission. No matter how much I ride it, I lament for the days of the older paddle. I find the newest version too tightly tucked into bars, and it’s made even more notable with a lock-on grip – like the grips included on the Mach 4 SL. This is a common complaint for a lot of riders on the new Transmission groups, so we wouldn’t be surprised to see something new offered soon.
Nitpicking…
This is a $13k bike, after all, so it’s fair to call out any issue no matter how petty. What left me a little bummed was that the Pivot wheel decals fell off of the Reynolds rims after a few washes. Not all of the decals fell off, but just some letters making the wheels say “Pivot.” If it was my bike, I could see going decal-less and embracing the matte-black carbon look.
So. Many. Batteries.
One necessary evil of SRAM transmission and Flight Attendant suspension is the number of batteries. There are LOTS of batteries on this bike, and as someone who regularly forgets to charge everything… it frightens me slightly.
On the Pivot Mach 4 SL, there are two SRAM AXS batteries for the suspension, one for the AXS dropper seatpost, and one for the SRAM AXS Transmission rear derailleur. There is one CR2032 coin-type battery in the AXS shifter, one in the AXS dropper, and one in the AXS power meter. That brings the total number of batteries on the bike to seven. Do you trust yourself to charge, or have replacements on hand?
Would you race the Pivot Mach 4 SL with a Flight Attendant? This is a dumb question because the answer is obvious: YES.
Is SRAM Flight Attendant the best spec for the bike? In a perfect world, I would love to see what a 100mm Flight Attendant spec would feel like. But in the wake of modern XCO courses and longer marathon-style races. This is the best spec for the Mach 4 SL, as long as you’re a Rock Shox suspension fan. Those who live the FOX life will most definitely need to ride the two options to determine the best one for them.
Final Thoughts
You’d think that reviewing a $13,500 race/marathon-focused mountain bike would be easy. Of course, it’s fantastic and fun, and we would all like to have one in our garage.
But is it worth the asking price? Well, for that one, I would ask what’s most important to you as a rider. The Pivot Mach 4 SL frame is an excellent canvas for building a hell of a race bike. Electronic suspension is newer to the market and is constantly being reworked. I wouldn’t be surprised to see new models every year. I suggest this build to any rider who loves to experience the latest and greatest that the mountain bike world has to offer. You are riding as close to what the world’s most prominent professional riders are using. If you have the means and want to experience Pivot’s best, this is it.
If you’re looking to get the most bang for your buck on a race bike while still being able to pay rising race entry fees… and stay in the Pivot ecosystem, I would say look into the Mach 4 SL Team and Pro version that uses the same frame, only with different components.
