Having tested Shimano’s R785 hydraulic disc brake for road bikes, we can state unequivocally that it offers superior braking to a conventional rim brake, and by ‘superior’ we mean that it gives the rider much greater control.
It achieves this by allowing progressive braking, a benefit obvious even in the dry conditions of our test descents of Mount Etna, and one likely to increase massively in the wet. Additionally, there will be no need for a pre-braking phase to scrub water from the braking surface. We expect other benefits from a system that removes the rim from the braking mechanism too, notably protecting its structural integrity from wear and heat damage, but we’d need a longer test period to establish this. Watch this space.
On the downside, the brakes were noisy, heavier than a rim brake, and aesthetically challenging. Beyond that, there are significant issues for Shimano and the cycle industry to agree upon if the system is to be widely adopted, notably concerning chain line (possible solutions include longer chainstays or reduced bottom bracket width), and post mount standards for the mounting of the front caliper. Given the industry’s seeming aversion to consensus (witness the current proliferation of BB standards, and before that, of headsets), this presents a not inconsiderable challenge.
Shimano, in fairness, make little secret of the fact that the R785 is ‘version one’ of their hydraulic disc brake for road bikes and readily admit that evolution will deliver more road-specific systems to replace the adapted mountain bike technology that underpins this first offering.
You’ll be able to read far more on the development and design philosophy of the R785 tomorrow in our ‘Industry Insider’ interview with Shimano Europe’s production co-ordinator, Tim Gerrits.