Irish rider Nicolas Roche has suggested that the course changes to the Clasica San Sebastian will explode the race, saying that the new Bordako Tontorra climb will shatter the peloton and limit the numbers of those in contention.

“I think it is probably the hardest climb there is on the course,” he told CyclingTips on Friday. “It’s also probably one of the hardest ones in the year. It is very similar to the old one they had in Lombardy a few years ago, but on a much narrower road, very slippery.

“Today was just humid, but when you get out of the saddle the back wheel slips a bit. After 225 or 230 kilometres, I think it is going to make a big difference to the race.”

The race was previously shaped by the Jaizkibel and Arkale climbs, with each being climbed twice. The modified route still includes these ascents but the race ends with a 15 kilometre finishing loop which takes the riders high above the city.

The key is the second category ascent of Bordako Tontorra, which includes several stretches of 20 percent and which tops out just seven kilometres from the finish line.

Roche believes it will have a dramatic effect. “There is usually a group of five, six away and then fifteen chasing. Tomorrow I think it will be more likely to see groups of ones and twos coming to the finish,” he said.

The gradient isn’t the only factor. “The road is narrow, it is just the width of one car. So I don’t know where the crowd is going to fit, to be honest.”

Roche has ridden well in the race in the past, finishing fifth last year and eighth in 2010. This time round he has done the Giro/Tour de France double for the first time, and so has an extra Grand Tour in his legs. Nevertheless, he’s hoping to once again show strongly.

“I did things pretty much like the other years after the Tour, so I hope I will be going well,” he said. “I took the usual Monday, Tuesday off, which I was always do, then I did a ride Wednesday and then a good four hours Thursday.

“I just travelled and did an easy ride today [Friday]. It is a copy and paste of what I have been doing over the last few years.

“At the start of the race I need time to wind up again, then I usually come through at the finish. Hopefully this year it will work again.”

Roche and team-mate Michael Rogers will likely share leadership in the event.

The Irishman is strong on short, steep climbs, but he admits that he is unsure how well the final ascent will suit him. “It might not be great for me, we’ll see,” he said. “I think it suits Dan [Martin, his first cousin] perfectly. I think the other climbs [the Jaizkibel and Arkale ascents] were always kind of good to me, but we’ll see how things work out.”