Test riding the new Shimano disc brakes … in Hawaii

by CyclingTips


While some of us are stuck in the office here in Melbourne, CyclingTips’ newest employee Andy van Bergen is over on the Hawaiian island of Maui for a Shimano media camp to experience the company’s new Ultegra road groupset, including their much anticipated disc brakes. Andy filed this report after testing the new disc brakes on a range of terrain, including the epic 55km descent off the Haleakala volcano. Here’s what Andy had to say about the trip.

Shimano has just released its Ultegra 6870 groupset – with the trickle-down technology from Dura Ace that we have come to expect with each new release. These updates once again improve the functionality of the Ultegra components, but it was the addition of road disc brakes that we were most excited to see.

There has already been plenty written about why disc brakes could make their way into the road market – from increased stopping power in the wet to the reduction of brake fade on sustained descents.

So when it came time to actually test them in real world conditions the natural proving ground would have to be the descent with the greatest vertical drop in the shortest distance on the planet – the 3,000m extinct volcano Haleakala (pronounced hah-lee-AH-kah-la) on the Hawaiian island of Maui.

Rising out of the beachside town of Paia Haleakala pushes its way upward for nearly 60km through several temperature zones and vegetation – up through a layer of perpetual cloud (which would later dump sleet on us, despite it being a 30 degree day) and up to its red, Mars-like, barren summit. When chiselling out the road to the summit, clearly a special consideration for the cyclist was made. Hairpin after hairpin stacked upon one another in deeply cambered and perfectly smooth hotmix.

As mentioned, the Shimano camp was put together to launch the Ultegra 6870 Di2 groupset, including the hotly anticipated R785 Hydraulic road disc brakes. The groupset itself now features a smaller and sleeker design, with the whole groupset (internal battery) dropping 126g from the current Ultegra 6770 Di2. The Dura Ace trickle down features reduces the weight to a point where it is actually 9g lighter than the mechanical 6800. A topcoat of paint perhaps, but lighter nonetheless.

Another significant but expected change was the adoption of 11-speed gearing. The standard 23, 25, and 28 tooth options can be supplemented with the addition of a long-reach cage, extending the gearing options to include the pie-plate-sized 32-tooth cassette. Combined with three choices of a new four-arm crankset (50×34, 52×36, 53×39) you really do have a versatile selection of gearing options at your disposal.

The popular Dura Ace E-Tube plug and play system allows users to modify shifting options simply by porting them into either a standard three-port or a five-port junction box. Shift buttons can be added Roubaix-style to the top of the handlebars, or alternatively can be set for sprint shifting. The levers have taken a further ergonomic tweak and set shifting buttons are now more comfortable to reach.

Before testing out the R785 road discs, it was important to put the new iteration of Ultergra Di2 to the test. Over two long rides the system delivered everything promised with the quiet efficiency of Di2. At one stage while rolling mid-peloton on fresh hotmix there was a discernible lack of noise from within the group. After putting 25 bikes through their paces on a mixture climbs, fast-paced descents, in the dust, blasting heat, salty sea spray, rain and sleet the same couldn’t quite be said the next day.

Taking my Specialized Tarmac SL4 up to 2,000m on Haleakala was a great final reminder of the familiar rim-braking technology prior to the switch to hydraulic disc brakes. In a bunch of riders, half of which were sporting discs, it soon became apart why the UCI is keen to keep the two variants separate.

Following lines and braking speeds into corners saw the yellow double lines swing up a little too quickly for comfort with regular brakes. A tightening right-hander almost resulted in a spill, and as the disc-clad riders pulled up quickly for a stop sign there was a genuine sphincter-tightening moment as the callipers only just pulled me up in time.

The next day I switched over to a Colnago C59 in a polarising matt army green, rigged with hydraulic disc brakes. The bike had been ridden the day before by a rider with an additional 30kg of brake loading – but the 140mm rotor remained the same. The one-size-fits-all mentality is due to the steel-alloy-steel sandwich construction of Shimano’s new Icetech rotors. Smaller rotors require greater cooling and the Icetech material combined with heavily finned resin callipers (choice of a heavier steel for constant wet conditions) provides that in spades.

The compensation for the discs that were about to get a +/- 3000m run-in was the additional weight in the form of discs (342g) and the relatively gainly disc-specific RX31’s (weighing in at a somewhat portly 1795g). If ever there was a bike to make up for these gains it is the Colnago C59.

The grinding 58km climb up Haleakala and multiple pitches didn’t result in brake rubbing against the wheels or frame – even when the road kicked up. Negotiating each set of cattle grids did result in an annoying metal ping, but a quick squeeze of the brakes seemed to fix this each time.

After turning around at the summit of Haleakala (3,000m above sea level) it only took a handful of corners to dial in the brakes. Descending the moonscape became a familiar pattern of late brake into a tight hairpin, push hard out, and carry more speed into the following switch. Each corner brought more confidence on the bike – and Shimano make no bones about the fact that it is the unconfident descender who will benefit the most from this upgrade. That said, disc brakes still attract stronger riders.

We were joined by both a former US domestic pro Neil Shirley — who happened to set a second overall on the Halakala Strava segment behind ‘Dean Murdoch’ who bears an uncanny resemblance to Ryder Hesjedal — and Australian NRS rider Dan Bonello, both of whom stated they were impressed by the increase in speed they could carry into each corner, and the ease of braking.

The non series XT callipers are essentially unchanged from MTB (and therefore leave plenty of scope for a weight-dropping Dura Ace upgrade in the future). Levers are adjustable both for reach and for lag to allow you to tailor to your style of riding. This adjustment is also available in the 6870 with pivot brakes, however the most surprising difference with the R785 is the lack of force required to apply brakes. While the effort required is minimal, this is not just a case of full lock on or off – Shimano have worked hard to allow a surprisingly huge amount of modulation when applying brakes.

In a practical sense for our descent this meant coming hot into corners, and braking later and later each time. When the road did tighten up a small amount of feathering could be applied mid corner without having to worry about running out of space or locking up the wheels.

When descending in a pack the ease of adjusting speed quickly, precisely and consistently is obvious. This is equal parts practical, and confidence inspiring — and another reason why an all-in or all-out approach to hydraulic discs in the peloton should be considered.

The lack of force required to apply the braking does become apparent on a sustained descent – it can literally be applied with one finger. Descending in the drops is always more comfortable, however with the lack of leverage required to apply braking force it is quite comfortable riding from the hoods – particularly when in a pack.

Aside from a few kilometres of descending in the rain and sleet all of the braking was conducted in dry environment. In the wet it certainly felt like it was a case of the tyres giving out before having to worry about pulling up in time for a bend, but a longer descent in truly soggy conditions will be the true test. Reportedly this is where they shine.

The aesthetics of the switch to discs is polarising. In order to house the oil reservoirs the hoods have been squared and slightly extended. While they look larger, in the hand they have a great solid feel, and once on the bike they are forgotten completely. Running this in conjunction with the Di2 system means there is space left to incorporate the reservoirs, and the stack is not too great.

It’s interesting to see Shimano’s approach in launching the discs at the Ultegra level, with both the levers and wheelset providing some low-hanging fruit for an upgrade to Dura Ace in the future. Despite the appeal for the Andy Schleck-like descenders in the pro peloton, the biggest benefactors of this technology are not going to be at the elite level – it is at a club, fondo, or recreational level.

There are not many additions to road bikes in recent years that have not been led from the pro peloton down but the launch of this product to the biggest slice of the pie in Ultegra may see this change. Shimano are joint lobbyists to the UCI to have disc brakes adopted, and it does need to be an all or nothing approach.

What the future holds for discs at an elite level remains to be seen, but for all other road cyclists it will have a huge impact on the way we ride. In a sport of incremental gains, this technology has the potential to be a game-changer.

For more information about disc brakes for road bikes, check out this article we wrote recently, including quotes from Shimano, SRAM and the UCI.

Disclosure statement: Andy’s trip to Hawaii, including flights, meals and accommodation, were provided by Shimano, whom we would like to thank for this opportunity. No payment was made for this article. Shimano advertises separately on CyclingTips.

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