Shimano Disc Brake Groupset Review

Shimano Disc Brake Groupset

The Japanese firm’s original offering was a pair of non-series hydraulic disc brake sets – ie not part of its standard groupset line-up. By testing the water first in this way, Shimano has been able to develop, update, revamp and improve its technology, learning as it goes along, before incorporating the two versions into the top-end Dura-Ace and Ultegra groupsets to create a harmonious look and feel with other components.

Last year, Shimano also launched a third option, RS505, which is roughly equivalent to the 105 groupset and presumably will be incorporated into that range in due course.

The range is now simpler to understand. Starting with the headline act, Dura-Ace, there are two versions of its hydraulic brake/shift levers – both use the same hydraulic technology but with either mechanical, cable-operated shifting (ST-R9120) or electronic Di2 (ST-R9170) options.

Both pair with the same hydraulic calliper (BR-R9170). Shimano has managed to package the hydraulics to fit inside the same shape brake hoods as the non-hydraulic versions, without the need to add lumps and bumps – a remarkable feat of industrial design that means that whichever shift and brake style you choose, the shape of the hoods will feel the same.

A key part in the update is in the rotor itself, using what Shimano call Freeza technology, with an extended brake surface area which makes it much easier for heat to dissipate and thereby improve braking performance (hydraulic brakes ’fade’ with excess heat build-up). This tech has been carried over to the Ultegra model, albeit at a slightly lower spec.

Just like its big brother, Ultegra’s disc brake options fully complement the rest of the groupset in terms of style and quality, and come in both Di2 (R8070) and mechanical (R8020) shifting formats.

Both Ultegra and Dura-Ace systems use mineral oil fluid with a reservoir tank in the hood that auto adjusts as the pads wear, and incorporates an adjustment for the free stroke of the brake lever before the pad starts to hit the rotor.

RS505 could be described as an interim or stop-gap option, which probably doesn’t give it due credit as it’s built to match the 105 level of specification, which we’ve found to be an excellent performer over the years.

Seeing as 105 currently offers mechanical shifting only, the RS505 follows suit, with no electronic option. The shape of the hoods is quite different to the standard 105 levers, being longer and broader, and they’re not to everyone’s liking so it’s worth trying before you buy to see if they suit your hand shape.


Elegant, sleek looks – especially with Dura-Ace-and excellent performance at all levels.

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