Wil reviews the brand new Pivot Mach 4 SL
The Mach 4 SL debuts in 2019 as a freshly baked model for Pivot Cycles. With a sleek carbon fibre frame, 29in wheels and 100mm of efficient dw-link suspension, it slots into the Pivot lineup as the flagship full suspension XC race bike.
In some regards, it’s actually an amalgamation of two existing Pivot models; the Mach 429 SL and Mach 4 Carbon – two very popular bikes on the privateer race circuit. Compared to those two bikes, the Mach 4 SL is lighter, with a more compact suspension package and modernised geometry that’s inspired by the Trail 429.
Labelled as a ‘gravity defying rocket ship’, the Mach 4 SL is purportedly the lightest and fastest full suspension bike that Pivot Cycles has ever produced.
Without doubt, it’s up there as one of the best XC bikes I’ve ridden. So let’s take a closer look at exactly what makes this bike tick.
Big Wheels Only Club
Firstly, the Mach 4 SL is rolling exclusively on 29in wheels. Given how popular the 27.5in Mach 4 Carbon has been (especially in the XS and S frame sizes), this is a pretty bold move.
Pivot is confident in its decision though, particularly because the Mach 4 SL will be offered down to an XS size – something that wasn’t possible with the previous Mach 429 SL. And how’s this – there’s actually more standover clearance in the new XS frame than there was with the 27.5in bike.
In order to lower the top tube and accommodate riders as short as 4’10” (150cm), Pivot has flipped the shock to a vertical position. It still uses a dw-link suspension design, with two small machined alloy links connecting the one-piece carbon swingarm to the mainframe via Enduro Max sealed cartridge bearings. Pivot says the overall behaviour isn’t all that different, but with the shock mounting at the bottom bracket instead, the mainframe can be made more compact.
Even with the lowered top tube though, each frame size – including the XS – will accommodate a full size water bottle inside the mainframe. And you can bolt one underneath the downtube too. Those endowed with extra long pins will be pleased to know that the XL frame will actually take two medium bottles inside the frame.
As a proof of concept, Pivot had both 27.5in and 29in alloy prototypes welded up in its Phoenix-based R&D facility. These were both built in an XS size for Chole Woodruff – an American XC racer, and one of Pivot’s sponsored athletes who played a big role in the Mach 4 SL’s development process.
While Chloe has enjoyed plenty of success on her much-loved Mach 4 Carbon, there have been times during World Cup races where she’s felt at a disadvantage to those on 29ers. However, at 5’2” (1.58m) tall, she wasn’t able to fit onto the Mach 429 SL.
On top of this, development of lightweight 27.5in components, including wheels, tyres and forks, is slowing down significantly. Going forward, this will severely limit choices for XC racers who need them for different courses and conditions.
With the new Mach 4 SL though, Chloe was able to get the standover clearance she needed, along with that crucial water bottle clearance. And once Chloe was happy with the handling and fit of her prototype, Pivot decided to fully commit to the big wheels.
High-Tech Carbon Frame
As well as being more compact, the new Mach 4 SL frame is also lighter. Slimmer and straighter tube profiles replace the swoopy-droopy look of previous models, and frame weight drops down to just 2105g for the XS size with shock. That’s over 300g lighter than the Mach 429 SL, and 225g lighter than the Mach 4 Carbon.
There’s less alloy bonded into the frame, with both the headset and pivot bearings now pressing in directly. Having co-developed the press-fit BB standard with Shimano over a decade ago, Pivot continues on with a huge 92mm wide shell on the Mach 4 SL. Despite many UK riders’ disdain for press-fit BBs, Pivot remains confident in its execution, stating that it manufactures the BB shell to an even higher tolerance than the head tube. Complete bikes come spec’d with a high quality Enduro bottom bracket with alloy press-fit cups.
The Mach 4 SL’s swingarm is more compact than its predecessors, with the slender tubing and bolt-up 148x12mm rear axle ensuring a narrow profile for sneaking through tight rock gaps. No, there’s no Super Boost Plus 157x12mm hub spacing here, since the Mach 4 SL is a dedicated 29in race bike. There is no provision for 27.5+ wheels as with Pivot’s Trail 429, Switchblade and Firebird 29 models.
Since the frame is 1x specific, the drive-side chainstay now takes a more direct route from the lower pivot to the rear axle, which makes it lighter and stiffer. Double uprights on the swingarm also increase rigidity.
There’s plenty of heel clearance, despite there being room to run a World Cup-able 38t chainring. Oh and for those wondering, Pivot says a 2.5in Minion DHF will fit in the back. With the more conservatively-sized 2.2in Ardent Race tyres on our test bikes, there’s loads of mud room. Pivot has also added a neat rubber shield over the lower dw-link to keep rocks and debris from working into tight gaps.
As you’d expect, the Mach 4 SL gets full internal cable routing via the Cable Port system. Unbolting the ports reveals a large hole to poke cables in and out of, and they can be pulled taut before being bolted back down to keep everything snug and slap-free.
Given Pivot’s previous embrace of Di2, it’s surprising to see the Mach 4 SL skip Di2 compatibility. According to Pivot’s CEO, Chris Cocalis, they’re still yet to hear any concrete plans from Shimano regarding future electronic MTB drivetrains. Top-end builds will be available with SRAM’s wireless AXS drivetrain though.
New-School XC Geometry
Inspired by the latest Trail 429, the Mach 4 SL brings a contemporary approach to its geometry.
Depending on your preferred flavour, the frame will take a 100-120mm travel fork with a 44mm offset. Most builds come with a 120mm travel Fox 34 Step-Cast, while the super high-end ‘World Cup’ models come spec’d with a 100mm travel Fox 32 Step-Cast fork. For more information on the various build kit options and pricing, check out the news story here.
On the note of the World Cup model, I did manage to weigh a Medium bike at the launch, which was outfitted with the XTR build kit, a carbon seatpost, a lighter bar & stem, and the regular cable-activated suspension package. The weight? Just 9.47kg (20.9lbs) without pedals. Hot damn.
With the bigger fork option, the head angle sits at 67.5° and the effective seat angle at 73.5°. The reach is actually identical to the Trail 429, sitting at 427mm on my Medium test bike. It’s worth noting that reach increases to a roomy 440mm with the shorter travel fork though, which is identical to the Santa Cruz Blur I’ve been testing lately.
Compared to the 429 SL, the new Mach 4 SL’s rear centre length is much shorter at 431mm (down from 446mm). However, the overall wheelbase length has grown significantly – on my Medium test bike it increases from 1121mm to 1146mm.
Also of note is the short and straight seat tube, which offers a usable insertion depth for longer stroke droppers. My medium bike came with a 125mm Fox Transfer, but I could easily bump up to 150-160mm travel.
Fox Live Valve
Pivot Cycles has worked closely with Fox Racing Shox on its Live Valve suspension system, and the Mach 4 SL features full integration for the rear sensor, internal wiring, and the control unit.
Each spec level will be available with a Live Valve upgrade, which comes with both increased cost (it’s a £1,950 / $3,000 AUD up-charge) and weight (around 200g).
If you’re not familiar with Live Valve, you should definitely check out Chipps’ detailed ride report.
In a nutshell, it’s a system that offers automated, electronically-controlled damping for both the fork and shock. Instead of the rider having to toggle handlebar remotes and lockout levers, the system does all the work for you, with the key goal being improved rider efficiency.
Three sensors (one on the back of the fork arch, one in the control unit, and one near the rear brake) measure incoming bump forces, and the on-board computer determines whether the suspension should be open or closed. Additionally, a 3-axis accelerometer works out if the bike is climbing, descending, on flat terrain, or in the air, and the decisions it makes are influenced accordingly.
The response rate is fast. The sensors read inputs 1000 times per second, and the damping can switch from open to closed in 3 milliseconds. According to Fox, the control unit will make on average around 480 mode changes per hour of XC racing.
All of the internal settings are predetermined by Pivot and Fox. The ‘Closed’ setting isn’t quite a full lockout, but it’s a relatively firm compression setting. In comparison, the ‘Open’ setting is about as plush as you can get given the Mach 4 SL’s minimal travel. You can adjust the Open setting with a 3mm hex-key, which offers 18 clicks of low-speed compression damping from full plush (0) to full firm (18). Due to the added efficiency the Live Valve system brings to the table, Fox recommends leaving the LSC setting in the plushest setting.
You can also adjust the sensitivity of the system via buttons on the battery pack. There’s an on/off button, and a mode button that will first display the battery life, followed by the sensitivity setting. ‘1’ is the most sensitive setting, meaning the suspension will open up more easily. ‘5’ is the least sensitive, so the suspension will remain in the Closed setting for longer.
Everything is waterproof to the IPX7 rating, and the system uses plug-in wires for the fastest response rate and low energy consumption. Battery runtime varies between 20-40 hours, depending on how rough the terrain is and what setting you’re running. A full charge takes two hours, though a 15 minute panic-charge will give you an hour of trail use. If the battery does die on you though, the fork and shock will thankfully switch to the full open setting.
Setting Up Live Valve
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Pivot Cycles Mach 4 SL Team XTR
- Frame // Hollowbox Carbon Fibre, 100mm Travel
- Fork // Fox 34 Step-Cast Live Valve, Factory Series, 44mm Offset, 120mm Travel
- Shock // Fox Live Valve, Factory Series, 190x40mm
- Hubs // DT Swiss XRC 1200, 36pt Engagement
- Rims // DT Swiss XRC 1200, 28h, 25mm Internal Rim Width
- Tyres // Maxxis Ardent Race EXO TR, 120tpi, 2.25in Front & Rear
- Chainset // Race Face Next SL, 34t Chainring
- Rear Mech // Shimano XTR, 12-Speed
- Shifter // Shimano XTR, 12-Speed
- Cassette // Shimano XTR, 10-51t, 12-Speed
- Brakes // Shimano XTR Race, 160mm Front & Rear Ice Tech Rotors
- Bar // Phoenix Team Low-Rise Carbon, 35mm Diameter, 740mm Wide
- Stem // Phoenix Team XC/Trail, 35mm Diameter, 60mm Long
- Grips // WTB Padloc, 30mm Diameter
- Seatpost // Fox Transfer, 30.9mm, 125mm Travel
- Saddle // Phoenix WTB Team Volt
- Size Tested // Medium
- Sizes Available // Extra Small, Small, Medium, Large & Extra Large
- Weight // 11.37kg / 25.01 lbs
- RRP // £10,750 / $15,999 AUD
Wil’s flights & accommodation for this trip were covered by Pivot Cycles.
|Product:||Mach 4 SL Team XTR|
|From:||Upgrade Bikes, upgradebikes.co.uk|
|Price:||£10,750 / $15,999 AUD|
|Tested:||by Wil Barrett for 3 days|