Rab Cinder Kinetic waterproof pants

The £210 Kinetic waterproof mountain bike trousers are part of Rab's recently launched Cinder range, which spans more than 30 pieces of kit to mix and match depending on the conditions.

Rab's overall aim is to incorporate materials and clothing tech developed thanks to years of experience into a coherent set of cycling gear.

The UK brand is known for making long-lasting products that can handle the worst conditions. Its outdoor heritage is obvious in the 3-layer Proflex fabric used in the Kinetic trousers. It has a unique 20k waterproof and 35k super-high breathability design.

Developed in-house, the material enables Rab to “make softshells with the waterproof protection of a traditional hardshell”. Rab claims that, as you sweat more, Proflex’s waterproof membrane responds by absorbing and dispersing moisture to equalise the balance of water on both sides of the fabric.

Rab Cinder Kinetic waterproof pants details and specifications

Described as having a slim fit, Rab has positioned individual panels of material to improve the pants' freedom of movement.

Some of these have been reinforced – such as the one-piece saddle panel and driveside hem patch – to protect from damage, but are slightly less breathable (25k) than the lighter 10k waterproof sections.

The thicker, tougher and more waterproof (20k) material protects against dirt ground in by the saddle and any chain damage. It is also used on the inner thighs, an area that gets exposed to a lot of rubbing.

Delving deeper into the Proflex fabric reveals how Rab uses an incredibly thin, very stretchy PU membrane that’s solid, unlike typical microporous alternatives such as Gore-Tex.

The design attracts moisture to its inner surface and moves it outside in a process of osmosis, rather than water vapour passing through in the way most waterproof membranes work.

Rab Cinder Kinetic waterproof pants performance

Rab’s Cinder Kinetic pants have a reasonably close-fitting cut and are quiet when you move.

They’re highly stretchy and unrestrictive while pedalling, with enough give to fit slimmer knee pads.

The high-back waist setup is secure, although the thin elastic on the small tensioner pull isn’t particularly taut, and the lower leg has a long zip for easy removal when muddy.

The shape isn’t heavily tapered below the knee, which makes the Kinetic pants look a bit more like regular outdoor trousers. This is amplified by the blue or two-tone colour schemes, which aren't as easy to keep clean as black.

The supple Kinetic fabric means freedom of movement is excellent.

When climbing for long periods in milder weather, breathability is so effective that heat and sweat get pumped out faster than they're generated.

In heavy rain and when splashing through deep puddles, Rab’s thin and stretchy softshell is really protective and only let in a few spots of water after about an hour of hammering.

However, when it looks totally wetted out and about to leak, water never truly penetrates to the extent of other waterproof trousers; moisture somehow stays trapped in the fabric.

Rab’s trick seems to be expelling so much moisture from inside that it never gets too heavy or clammy, while the fabric is incredibly quick to dry.

In terms of water and wind protection, as well as breathability, the Cinder Kinetic trousers offer unreal performance. However, the styling and construction feel a bit more targeted to XC or gravel riding than enduro or electric mountain bikes, where there's constant mud and the risk of crashing.

Rab's thin and lightweight trousers survived plenty of rubbing and snagging during several long rides, but a slightly more robust and warmer alternative would likely offer extra protection for gravity riders doing uplifts or ebike riders.

Rab Cinder Kinetic waterproof pants bottom line

Rab’s Cinder Kinetic trousers function exceptionally well for regular mountain bikers.

However, they're not the thickest or toughest pants for enduro or DH riders more likely to crash in winter and potentially damage the fabric.