Solid road and cyclocross 4-piston calipers

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With over 25 years of experience designing and building hydraulic disc-brake systems for mountain bikes, Hope is targeting road, cyclocross and gravel bikes with the RX4+ hydraulic disc calipers.

To simplify your decision-making, the RX4+ calipers are compatible with all common Shimano, SRAM and Campagnolo drop-bar hydraulic brake levers.

Because Shimano and Campagnolo systems use mineral oil, and SRAM brakes use dot fluid, Hope makes calipers specific to each type, with a letter ‘M’ or ‘D’ etched onto the bore cap.

The calipers are CNC machined from solid 2014 T6 aluminium in Hope’s Barnoldswick factory, and come in six colours.

Versions for either post-mount or flat-mount road disc brake setups accept 140mm, 160mm and 180mm rotors.

Each caliper comes with two pairs of Hope disc brake pads, recommended for road and gravel use, a caliper bleed kit, and the necessary fittings for your frame and brake line, plus instructions.

Including pads and spring, my Flat Mount Front +20mm caliper (for 160mm rotor) weighed 119g, and the Flat Mount Rear 101g, both lighter than Shimano’s GRX400 calipers.

Their cost puts them between Shimano’s Ultegra and Dura-Ace, and similar to SRAM’s Red calipers.

The RX4+ is termed a monobloc design, because it’s formed from a single piece of aluminium, making it stiffer than a two-part caliper and allowing its four pistons to squeeze the pads firmly and squarely against the rotor every time.

During setup, Hope’s bleeding process was a little more involved than the big brands and required the syringe to be fitted and removed several times during the routine. That wastes a small amount of oil, and requires a bit more cleaning up afterwards, but Hope does provide all the necessary kit.

This was, however, the first bike I’ve built with Hope’s hydraulic disc brakes and I expect the process will become simpler with repetition, as it has when working on Shimano, SRAM and Campagnolo products previously. Many riders will also rely on a bike shop for bleeding.

In terms of performance, despite weeks of road and off-road muck and grime regularly coating just about everything through the testing period, the brakes kept working well.

Brake rub was a rarity, occurring only when water or liquid temporarily filled the gap.

Brake feel via Shimano’s excellent GRX levers is at least on a par with any road disc brake, with superb fine control and phenomenal power when needed.

Whether on tarmac, gravel or wet trails, the RX4+ gives enormous confidence, and pad wear is no worse than its rivals.

Hope has poured all of its experience into the RX4+ calipers.

The result is dependable performance for both road and gravel riding.

Robin Wilmott is a freelance writer and bike tester. He began road cycling in 1988 and, with mountain bikes in their infancy, mixed experimental off-road adventures with club time trials and road races. Cyclocross soon became a winter staple and has remained Robin's favourite form of competition. Robin has always loved the technical aspect of building and maintaining bikes, and several years working in a bike shop only amplified that. Robin was a technical writer for BikeRadar for nearly a decade, and has tested hundreds of bikes and products for the site. He has also written extensively for Cycling Plus, Velonews and Cyclingnews.

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