A fast and frisky 650b version of Pivot's Mach 429 carbon 29er with echoes of the past
This is the new Pivot Mach 4 carbon; it features a full carbon frame, 115mm of rear travel and 650b wheels. If you’re familiar with the Pivot range, you’ll know the company has a Mach 429 carbon 29er in its line-up already, so why launch a 650b version?
Pivot says it wanted to produce a short-travel bike with the handling and acceleration of the old 26in Mach 4, but with some of the benefits of bigger wheels.
Need to know
- 650b, 115mm travel XC/trail bike
- Full carbon-fibre frame
- DW-link suspension design
- Future proofed for Shimano Di2
Using 650b wheels also allowed the company to produce a XS frame size, something that wasn’t possible with the Mach 429. So what are your options?
Like most of the Pivot range, the Mach 4 is available with several build kits — the SRAM X01 option that I rode costs £2,650 on top of the frame cost, or you can choose a Shimano XT build kit for the same price. There’s also a XT/SLX mix for £1,650.
Fancy a more racy set-up? The Mach 4 can be configured for cross-country competition by swapping the stock 120mm fork for a 100mm version and resetting the rear sag using a small guide on the shock.
Basically there are settings for both ‘race’ and ‘trail’, but because our supplied test bike came with a 120mm fork, I stuck with the trail mode exclusively.
In terms of intended use, the Mach 4 is a similar bike to the Saracen Kili Flyer 122 that won our Discount Bikes test in September 2014. It’s also short travel and has 650b wheels, but there’s a key difference in the geometry that makes one of them more fun to ride — the Kili is 20mm longer in the front centre.
The lack of length in the Mach 4 makes it feel twitchy and less stable, especially when riding rough or steep terrain. On the flip side, the carbon frame is incredibly stiff, it weighs practically nothing, has a ton of standover clearance and the DW-Link suspension is very efficient while still offering ample grip and control.
In terms of build quality, there aren’t many bikes that are better made than the Mach 4 — the level of detailing is superb. I particularly like the way the frame is future-proofed for Shimano Di2 and even features a compartment for the battery at the bottom of the down tube.
With 29ers dominating the short-travel market, 650b bikes are a rarity, but they can be fast, fun and flickable. The Mach 4 is certainly lively, but I think its sizing is a bit off. Ultimately, the Mach 4 is not as confidence-inspiring as the Kili Flyer or aggressive short-travel 29ers such as the Specialized Camber Evo or Kona Process 111.