This article originally appeared on BikeRadar
Shimano launched the latest Dura-Ace just ahead of the 2016 Tour de France; it was the biggest road group at the biggest road race. Some 14 of the 18 WorldTour teams used either full or partial Dura-Ace groups in 2017. But former European cyclocross champion Toon Aerts and others are racing it off-road, too.
I caught up with the Telenet-Fidea Lions rider Aerts at a World Cup in Germany to get his thoughts on Dura-Ace changes.
Dura-Ace for 'cross
The Shimano Dura-Ace R9150 rear derailleur hugs the rear wheel, reducing the risk of damage in a crash
Former men's world champion Mathieu van der Poel, current women's world champion Sanne Cant and last season's European champion Aerts are just a few of the riders equipped with Shimano Dura-Ace R9170 groupsets — the hydraulic disc brake/electronic shifting version of the series — for the season.
"I was very happy with how Dura-Ace was working [last year], but now it is better because the rear derailleur is not as big, so the derailleur stays under the frame," Aerts said.
"If you get close to another rider, the barriers or you have a crash; the derailleur is a little bit protected.
Shimano Dura-Ace R9170 shifters on Toon Aerts' Trek Boone
"Last year, here on this track, I had a crash and my bike fell on the side of the derailleur and lost some time. This year it shouldn't happen when you fall because it's not as big anymore.
"The shifter hoods compared to last year are smaller and similar to the standard road shifters, but they are for disc brakes.
Aerts runs Shimano XTR pedals alongside the Dura-Ace R9100 series crankset
"The difference between the lever this year and last year is noticeable. Last year if you stand on the pedals while on the tops and you shake your hands a bit, the brake was already closing but now there's a little more resistance, so if you hit the lever a little bit it's not braking already.
"When you shift there is now also a click, last year you hear nothing and feel nothing but the chain was shifting, but now you have the step. It used to be a bit of an issue with the brakes and the bumps in Cyclo-cross, especially with gloves and cold hands it wasn't always easy to control the shifters."
For Shimano riders, 46/39 chainrings combined with an 11-28 cassette was the common gearing choice
As Shimano sponsors Aerts, I wasn't expecting any negative comments on the groupset. However, having ridden several thousand kilometres on the Dura-Ace R9100 groupset on the road, and on the cobbles of Flanders and Roubaix, I can agree with several of the design benefits put forward by Aerts compared to the Dura-Ace predecessor.
The bikes go through several cleans throughout the day following warm ups and during the race, with the components taking plenty of abuse
On top of the performances by the athletes riding the groupset in cyclocross, the performance of the groupset coping with the mud, sand and dirt of the discipline — plus several jet washes in a single race day — is impressive. The true extent of the rigours can be seen in our Zeven cyclo-cross World Cup tech gallery.