Valentino Rossi will not use Yamaha's new aero fairing for this weekend's Austrian Grand Prix, after trying it in Monday's Brno MotoGP test.
Yamaha trialled the new sculpted fairing, designed to improve corner exit speed by keeping the front wheel on the ground under acceleration in the manner of the now-banned winglets, with both test pacesetter Rossi and team-mate Maverick Vinales.
Ducati introduced a similar update for its bike during the Czech GP weekend.
While Rossi says the fairing made the bike easier to ride, he will not use it for this weekend's Red Bull Ring race because it compromises top speed and the Austrian track features long straights.
"Maybe it is not the best fairing for Austria," Rossi said.
"Top speed is very important [at the Red Bull Ring] and with this type of fairing you lose a bit.
"The bike is more easy to ride, less wheelie, a little bit like the wings, but it looks like we lose a bit [of top speed].
"It can be a good option for other circuits."
As well as a new fairing, both Yamaha riders also sampled a new Ohlins carbon fork, a component Rossi described is "a good option" and expects to use at the Red Bull Ring this weekend.
Marquez tried Red Bull Ring ideas
Brno winner Marc Marquez was second to Rossi on Monday, 0.018 seconds behind, and said Honda had also worked on ideas for the Red Bull Ring.
"We try to avoid the wheelie because in Austria it will be important," said Marquez.
"We saw the other manufacturers were working on that side with the different fairings.
"We didn't have any fairings but we had a few ideas to try and we will see there because you need to find a compromise with good braking stability and good acceleration.
"The feeling was really good with the bikes, the cool temperature and the track was in a really good condition, it was a perfect way to try to understand a few set-ups thinking about Austria."