Bespoke Blog

Shimano's flagship groupset finally gets its own dedicated disc brakes. And they're good.

This is a first ride review of Shimano's new Dura-Ace R9170 groupset and we're focusing on the disc brakes - we'll go over the other aspects of the new groupset in a future article.

We've had to wait a few years, but the wait was worth it. The new Dura-Ace Di2 R9170 hydraulic disc brake groupset, the first disc brakes to wear the coveted Dura-Ace logo, offer truly stunning performance in a package that adds little extra weight over rim brakes. Truly, the disc brake revolution has arrived.

Shimano has been doing road disc brakes for some time now, but until now they've been non-series brakes, and if you look closely they had much in common with their mountain bike brakes. They were heavy, bulky and not all that pretty. This new Dura-Ace disc brake groupset is a serious step-forward in every aspect.

Part of Shimano's latest R9100 series range, you can choose mechanical or electronic shifting. I spent a couple of weeks on a Trek Emonda SLR with the Di2 version of the groupset, and where better to test disc brakes than riding up and down Mont Ventoux a handful of times.

The first thing you notice about the new groupset, when you're in the saddle at least, is just how compact the brake lever hoods are. It's damn impressive how Shimano has managed to package the hydraulics inside the hood without a noticeable increase in the hood dimensions. You can hop on a bike with regular Dura-Ace Di2 or mechanical and not notice any substantial difference in the shape and size of the hoods.

They're more compact and lower profile than SRAM's new eTap HRD, but of course, the shape and size of the hood you like comes down to personal preference. If you prefer small hoods though, Shimano wins hands-down. The carbon levers are ergonomically shaped and feel great under the fingers whether in the hoods or drops. It's the result of years of evolution, they simply feel superb in the hands.

- Related: SRAM Red eTap HRD groupset first ride

Pull the brakes and there's some serious stopping power available with these new disc brakes. They feel full of authority and firm. It's not a case of an on/off feeling either, the lever is progressive and the power builds up smoothly, with no vagueness or sloppiness in the system. It's easy to apply as little, or as much, power as you need to match any situation.

And fear not, you're not going to be locking your wheels all over the place, that simply isn't the case. Just like you do when you drive a new car for the first time, your brain adjusts and adapts to the braking force available and you modulate the available braking power. In hundreds of miles of riding, I never once locked a wheel, and that included some panic braking situations.

In the dry, the brakes are silent during use and oh-so-powerful. The advantage of discs over well set up rim brakes in the dry might be a narrower margin than the clear advantage that discs offer in the wet, but even in the dry, the Dura-Ace discs inspired way more confidence.

I rode some fast and fun descents in France during the Haute Route Ventoux event, and on more than one occasion I was glad to be riding the new Dura-Ace disc brakes. While my ride companions, all on rim brakes with carbon wheels, were braking well in advance of each corner, and accompanied by horrible screeching sounds and emitting a horrible burning stench, the disc brakes were solidly dependable. I was able to brake later and with more control, and there was no noise or smell either. No fuss or drama, just solidly dependable braking every single time.

It certainly boosts your confidence riding unfamiliar roads in a fast moving peloton I can tell you!

Riding in the wet reveals a huge performance boost. Carbon rims have evolved a lot over the years and the latest are much better in the rain than they ever used to be. But disc brakes trump even the best carbon rims in the rain. There's simply no detriment to the retardation available when braking in the wet, meaning you can ride with the same confidence in the rain as you would in the dry. For UK-based cyclists forced to ride in the rain through the winter, this is a huge advantage.

I love descending, it's the best thing about riding in the mountains, or one single mountain like Mont Ventoux. Coming back down is the reward for all the suffering on the way up, and usually where I try and catch people after being dropped on the climb. Even with the perfect conditions we had, I felt more confident braking for the corners with the Dura-Ace discs.

The brakes worked exactly the same from the first to the last corner. Nor was there any issue with heat buildup on those long mountain descents. Shimano has developed these funky new disc rotors (they look like something out of a sci-fi movie) which prevented any threat of heat building up. There as no fade, no noise, no drama. I could brake late and hard, or scrub off speed early, depending on whether I was cruising or attacking the descent.

So if it sounds like I'm impressed, well I am. Disc brakes have their lovers and haters, but if you are interested in disc brakes and are looking to build a new bike around disc brakes then you really should consider Shimano's newest Dura-Ace Di2 R9170 groupset. It's highly impressive.

- Related: Shimano Dura-Ace Past and Present