Ben Spies blames tyres for slump that cost him Aragon Grand Prix podium

The Yamaha rider took the lead at the start of the race, and though he was swiftly passed by the Hondas of Casey Stoner and Dani Pedrosa, he felt confident he could hang on to third.

But he started to lose speed as the grand prix progressed due to a decline in tyre performance, and ultimately fell to fifth behind his team-mate Jorge Lorenzo and Gresini Honda's Marco Simoncelli.

"I knew the start wasn't going to last long the way Casey and Dani were riding but I felt pretty good in the beginning," said Spies.

"Even when we got to the fourth or fifth lap I thought our advantage to fourth place was growing. I felt really comfortable and thought we had a podium fight in us.

"Then the sixth or seventh lap the tyre just made a huge drop and just kept going down. Usually they make one drop then stay consistent. I had no confidence in the rear and no grip.

"I'm frustrated as before that we were riding well and the bike was working great."

Team director Massimo Meregalli felt there was nothing Spies could have done to get around the problem.

"Ben really couldn't do more because the rear tyre was really bad after just a few laps," he said.