Speed Never Felt So Plush: Pivot Mach 4 SL World Cup XTR Review

Pivot Cycles released the Mach 4 SL last May under much fanfare. The brand and Pivot athletes touted the no-holds-barred racing chops of the new machine during the Sea Otter Classic that year. I was instantly interested and requested a long-term loaner to really put the screws to the new platform.

I tested the Pivot Mach 4 SL World Cup XTR for 8 months, thrashing it on my local race-oriented terrain. From super-fast, dry, hard-packed, and rocky trails to narrow and tight ribbons of softer dirt, I did my fastest off-road riding aboard the bike while it was in my clutches. I spent more anaerobic time on the Mach 4 SL World Cup than on any other bike I rode concurrently.

In short: The Pivot Mach 4 SL World Cup XTR was indeed a fast race bike. It was efficient, responsive, and light, just as you’d expect a “World Cup” bike to be. But it had a much plusher rear suspension that worked better for me on climbs than any other race bike I’d tested to date. Most importantly, it allowed me to have way more fun than I’m accustomed to on pure race bikes. But all this comes with a high price tag.

Pivot Mach 4 SL World Cup XTR Main Specifications

Pivot claimed to have refined its proprietary Hollow Core carbon fiber construction to ditch 300-400 g off the previous frame while improving the DW-link suspension. The Mach 4 SL inherited many design cues from the featherweight LES SL frame, including diminutive frame tubes, especially on the rear triangle.

This impressive mass loss of almost 20% was reportedly gained without any decrease in strength, stiffness, or negative impact on handling. Notably, Pivot uses different carbon layup schedules for each frame size to maintain consistent ride quality across the five-size range. And the brand doesn’t use a less expensive carbon on lower-spec versions.

Each Mach 4 SL frame accommodates at least one large water bottle, while the M, L, and XL frames can handle two. Two bosses are on the underside of the downtube, and three are on the bottom of the top tube. The frame is also compatible with the Universal Derailleur Hanger.

The World Cup XTR build is an enviable collection of top-end racing componentry. World Cup-proven Shimano XTR compenentry is matched with a Race Face Next SL carbon crankset and Reynolds Blacklabel 309/289 carbon rims with Industry Nine Hydra hubs.

Proven Fox Factory suspension graces both ends of the Pivot Mach 4 SL. A 100mm Step-Cast 32 fork manages the front, while a Float SL shock manages the DW-link rear end. Both can be actuated remotely, as can the Fox Transfer SL Factory Series dropper post.

The Mach 4 SL frame also has a flip chip on the rear suspension link. It provides 95mm or 103mm of rear travel on the World Cup versions. On the “standard” Mach 4 SL models, which have a longer shock and 120mm forks, the flip chip delivers 106mm or 115mm of travel.

Pivot adds to the uber-premium build with its in-house Phoenix Team bar, stem, and co-branded WTB World Cup Volt saddle with carbon rails. Finally, Maxxis Rekon Race 2.4″ TR EXO tires handle the traction department.

All this sounds dreamy, but it comes with a high price tag. The Pivot Mach 4SL World Cup XTR build will cost you an MSRP of $9,899. Builds range from “Ride” series versions starting at $6199 and top out with a Team XX Eagle Transmission Flight Attendant model at a whopping MSRP of $13,499.

Pivot Mach 4 SL Suspension Overview

Most XC race bikes I’ve tested recently have “flex-stay” rear suspension. This means that they forego using multiple linkages and pivots to save weight, reportedly improve durability, reduce maintenance, and yield higher lateral rigidity. This single-pivot and linkage design directly connects the rear axle to the frame via a solid swingarm. So, it relies on the inherent flex of the seat stays to provide the correct suspension kinematics.

As with anything, this dependence on flexing seat stays sacrifices something to gain the purported race-oriented benefits. The limited movement of the seat stays significantly reduces the suspension’s ability to provide plush travel while minimizing the adverse effects of pedaling, braking, and chain tension. It also limits the suspension designer’s ability to build in anti-squat and anti-dive characteristics.

Pivot licenses DW-link rear suspension for the Mach 4 SL. This bike was a rarity, as all the other race bikes I tested were flex-stay. Compared to these other bikes, the Mach 4 SL was a touch heavier at 24.2 pounds with a bottle cage, Xpedo M-Force 8 pedals, and tubeless setup. This was at least a pound heavier than comparably equipped flex-stay race bikes I’d tested for a few years. But it might be the lightest dual-link XC bike out today.

However, the Mach 4 SL’s DW-link suspension is much more complex than flex-stay rigs. Instead of the chainstays directly connecting the rear axle to the frame, a pair of short co-rotating links connect the solid, enclosed rear triangle to the frame. The DW-link requires twice as many pivots and bearings at the lower connecting point as flex-stay designs.

The DW-link system provides a “virtual pivot point” as the center of rotation of the rear triangle about the front triangle varies as the rear axle travels through its movement path. It also varies with weight distribution changes, pedaling forces, and braking demands. But again, this comes at the cost of greater complexity, potentially increased maintenance demands, more weight, and a possible loss of rigidity due to the added articulation points.

The Pivot Mach 4 SL World Cup XTR on the Trails

Suspension Action

On hardpack, the Pivot Mach 4SL World Cup XTR immediately felt like a scorcher for a dual-pivot bike. It rocketed forward with each pedal stroke, with a direct feeling between the pedals and the rear tire contact patch. This was surprising given the physical separation of the rear triangle and spoke volumes of Pivot’s version of the DW-link virtual pivot point system.

Yes, I could tell there were links and sensed a slight “stall” in power delivery compared to flex-stay bikes. But the benefits far outweighed any drawbacks once I was at a reasonable speed, and even more so at race pace.

After spending so much time aboard flex-stay race bikes, powering through chunky sections was an entirely different experience and made me smile every time. Pedaling or braking forces didn’t “jam” up the suspension nearly as much as I’ve felt on flex-stay bikes. This kept the tires more connected to the ground. And it kept the chassis and my body less disturbed.

This greatly enhanced my pedaling efficiency, traction, fatigue resistance, and flat-out enjoyment. The contrast to the other race bikes I was testing was astounding. But it was still a “stiff” ride compared to non-race bikes. There was no mistaking that this was still a “World Cup” machine.

The flip chip was super easy and quick to adjust, and changing the setting doesn’t alter the geometry. After going back and forth, I left it in the shorter 95mm travel setting. I didn’t feel like either setting altered anything in a negative way.

I think most people will prefer the extended rear wheel travel of the 103mm setting. The bike felt more connected and “poppy” with the shorter setting for the racier trails I rode most. And I felt like this setting balanced the bike better with the fork’s 100mm of travel.

Climbs and Descents

The DW-link really shined on climbs. Whether they were short and punchy or long and grinding, the suspension action, short chainstays, anti-squat characteristics, and the correct amount of reach for my 5’11” frame allowed me to stay seated, keep the power down, and maintain front-end tracking. It was the best climbing XC bike I’d tested in a long time.

With decidedly snappy handling, the bike handled descents surprisingly well for an XC race bike. The suspension action matched the sharp handling well. Of course, the bike was limited to what it could handle due to the short travel. But when I had to navigate around larger obstacles, the bike almost telepathically responded to my directional whims. Again, for a dual-link bike, the directly connected feeling was surprising.

My favorite local trail has several rock gardens on flat terrain where the Pivot Mach 4 SL stood out. I could pedal at a medium cadence, cleanly threading between boulders, staying seated, and pedaling over smaller rocks. All without a death grip or holding my body stiff to stave off getting thrown around.

Cornering

On smooth descents or fast-pedaling “flat track” sections, the bike carved bowls however I pleased. Wide arcs on the outside or cutting down underneath, the bike cornered without forcing it. I could pivot around the head tube on low-radius turns almost without thought.

The Pivot Mach 4 SL chassis also delivered the proper feedback to keep both wheels tracking on fast, loose, wide-radius turns. I trail braked late into these turns and knew where the limits of traction were.

The Pivot Mach 4SL World Cup XTR deftly flicked side to side while I maintained a high pedaling cadence and speed on faster, tighter, and narrower single tracks. I knew where my tires were on the sometimes impossibly narrow ribbon of rideable dirt and confidently made snappy direction changes. Maintaining speed and momentum in these situations was an incredible joy; the bike felt so at home.

Componentry Performance

There wasn’t much to say about the XTR drivetrain than “hell yeah” — everything worked perfectly. I never missed a shift, nor did I have any doubts that the shift would occur or if it had occurred. This still surprisingly non-electronic drivetrain provided 100% rock-solid performance. I felt that the RaceFace Next SL carbon crankset was fitting for such a racy bike. They felt remarkably stiff, and the rubber protective caps nullified my only fears of carbon cranks on MTBs.

Once bedded in, the XTR brakes were also equally flawless. They had a positive and crisp initial bite, perfect progression, and one-finger panic stop power. I have not used any CX brake better than XTR in quite a few years.

The Reynolds Blacklabel carbon 389/289 wheels with Industry Nine Hydra hubs were also a joy to use. They withstood harsh treatment from my area’s square-edged limestone rocks and blocks. And they felt properly resistant to torsional forces for a light CX wheelset when wedged between boulders in rock gardens. And who doesn’t love the sweet sound of the Hydra freehub?

Minor Nicks

As good as the Pivot Mach 4 SL World Cup XTR was, my job demands that I ferret out negatives. Of course, the high price ($9,899) is the one that sticks out. The lowest-cost Mach 4 SL has an MSRP of $6,199, quite a bit higher than other lower-spec XC race bikes.

An example would be the Trek Supercaliber platform, a World Cup contender; the low-spec version has an MSRP of $4,200. A similarly shod XTR full race rig carries a price tag of $9,550, so Pivot is in the range at this level. But still, $10K+ out the door is a lot of money, no matter what.

The WTB World Cup Volt saddle was not for me. I prefer a much firmer seating platform for XC MTBs. Again, it is just a matter of personal preference. I would also trim a bit off the house-brand flat carbon bars.

I know that racers need remote lockouts for the suspension, but I never felt the need to actuate the lockouts. Not once. And if I did race, I would replace the SRAM TwistLoc lockout control with a more standard, thumb-actuated unit. I didn’t like adjusting my grip to toggle the lockouts or being limited to the original grips to maintain the congruent feel.

Conclusions on the Pivot Mach 4 SL World Cup XTR

If you race and want a more compliant ride than flex-stay bikes, then the Pivot Mach 4SL World Cup XTR should be at the top of your list. Additionally, the DW-link was superior to flex-stay bikes in separating pedaling and braking forces from the suspension action, which was more efficient in the long run. Most importantly, I felt the bike made having fun while going as fast as possible an easier proposition.

These factors are even more relevant if you don’t race but enjoy riding at your limit on trails appropriate for a CX race bike. The plush-for-the-travel rear and snappy handling will be akin to driving a sports car instead of an SUV. I imagine a 120mm version of the Pivot Mach 4SL could be the choice for those who want a little more suspension travel but retain the other racy characteristics of the World Cup versions.

Again, if you are in the market for an MTB sports car, consider the Pivot Mach 4SL World Cup XTR. It really was that good. But just like any other flagship race bike with top-shelf components, be prepared for the high price tag.