Casey Stoner and Ben Spies have expressed concerns about proposals to scrap MotoGP's test day limits for 2012, saying it could leave top riders over-worked.
At present, testing with factory riders is restricted to a limited number of pre-season and mid-season tests. But there have been suggestions that next year this could be replaced with a limit on how many tyres are available for testing, but with teams allowed to test where and when they pleased within that tyre allocation.
World champion Stoner fears that could increase the demands on riders too much, even though he acknowledged that the factories were unhappy with the current limits.
"With an 18-race season and the testing we already have, I'm not really happy [at the 2012 proposal]," he said.
"I guess for people coming into the class, and people understanding the bikes, and getting data that's closer to race pace than unfortunately some of the test riders can produce, it's definitely a big help, but as far as testing goes, to be on the bike all year long is just going to destroy everyone, I think."
The Australian feels the current testing regulations allow sufficient mileage for all the development work required.
"Some people are definitely going to be motivated and definitely want to do it a lot more and might find rewards out of it," said Stoner. "Myself, we can get done what we need to in the tests that we have.
"Sometimes you feel like you need more testing, but if everybody's got the same, it's okay. I guess you're going to be able to choose how much testing you're doing and if it works for you or not, but it's going to be hard trying to fit that many test days in along with the races that we have to do and the other appointments that we've got away from racing. It'll end up a very, very big year."
Spies agreed that the schedule was already punishing and that he saw little need for further mileage.
"It's hard enough with how many races we have and the testing we have now," said the Yamaha rider. "The tyre allocation could help some people for sure - there are some guys that like to go out there and ride 100 laps a day and it doesn't really seem to do much, and there are some people who will do 30 laps and set the fastest time.
"We can only do so much, especially when we test at Sepang twice a year and it's like nine million degrees and we can't ride that much more if we have that many more tyres.
"For me, the way the testing is now is fine, but I can understand how for a rookie it might be better, so I'm not going to say it's a bad thing. Each to their own, I guess."