Aprilia has retained Stefan Bradl for MotoGP 2016, but with Sam Lowes to join its factory team the following year.

As expected, Bradl's new deal will see the German remain alongside Alvaro Bautista, while Lowes stays in Moto2 for one more season - albeit switching from Speed Up to a Gresini-run Kalex and taking on MotoGP testing duties.

"It's been a very difficult few weeks deliberating over what would be the best situation for my career and, while I had the opportunity to go straight to MotoGP, I followed my heart and listened to supporters who wanted me to try to win the championship next year on a 2016 Kalex," said Lowes, who revealed he has a two-year MotoGP deal.

"I'm determined to achieve that ambition, while also using the time to learn, develop and understand the Aprilia MotoGP bike during an intense test programme, which should help me to get up to speed for the 2017-18 championships."

Lowes has long been linked with Aprilia, although it was initially thought he would make the move to the premier-class next year.

However the waters were muddied when Bradl became available mid-season due to the turmoil at Forward Racing. The German took over the RS-GP abandoned by Marco Melandri from Indianapolis and was soon threatening the pace of Bautista (in the first year of a two-year deal).

"Stefan Bradl came on board almost by chance, a result of the circumstances, but his change in bikes this season was a pleasant surprise for me," said Aprilia Racing boss Romano Albesiano.

"From the very start we found him to be a methodical and fast rider, extremely precise in his comments and therefore particularly suited for the delicate role of "race tester" that our rookie season requires.

"Precisely for this reason we wanted to continue working with him and now it's official. Stefan will work alongside Alvaro Bautista who will be in his second year with Aprilia.

"In this 2015 season Alvaro is providing a fundamental contribution to development of the RS-GP. With Alvaro and Stefan we have two excellent riders on our team with the right skills, professionalism and motivation to grow the Aprilia MotoGP project."

At 25, Bradl is less than a year older than Lowes, but already in his fourth season of MotoGP. Both Bradl and Bautista have previously finished on the MotoGP podium with satellite Honda machinery.

"I am really thankful for the great opportunity that Aprilia Racing Team Gresini gave me in the second half of the season," Bradl said. "I would like to thank Romano Albesiano and Fausto Gresini for believing in me. At my first Grand Prix with Aprilia in Indianapolis I immediately felt really welcome by the whole team, I cannot really describe how professional everybody works in the team.

"I can say without a doubt that Aprilia is the best team I have raced with since starting my World Championship career. I have great support from my technical crew. I could tell from the first day that they really believe in me and I like the way they prepare and plan every session.

"Signing for 2016 gives me a lot of confidence for the upcoming races and it is great motivation to prepare for next season as best as possible. I know Aprilia has high expectations and I am confident that we have what it takes to be a consistent top ten contender for 2016. This must be our goal."

While Bradl got the nod for 2016, popular Englishman Lowes is to become an official Aprilia test rider and 'lay the groundwork' for his 2017 MotoGP race seat.

'Next season Sam Lowes will also be participating in development of the Aprilia MotoGP prototype as a tester,' said an Aprilia statement. 'This will lay the groundwork for Sam Lowes' participation in the 2017 MotoGP Championship season with Aprilia.'

Albesiano added: "For the work that will be done at Noale and by the test team we'll also be able to count on the contribution of a fast young rider like Sam Lowes who, along with his commitment in the Moto2 championship, will be working as our official tester."

Lowes will thus switch to the dominant Kalex chassis for a title assault in Moto2 next year, riding for the same Gresini team that hosts Aprilia's MotoGP project.

The Englishman joined grand prix last season as the reigning World Supersport champion and is the only front-running Speed Up rider, claiming his first podiums, poles and race win this year.

Aprilia's best result this season is tenth place, by Bautista at Catalunya and Silverstone. However 2016 will see the debut of an all-new prototype, the current machine still being heavily based on the RSV4 Superbike, while new rules mean the introduction of a standard ECU and Michelin replacing Bridgestone as exclusive tyre supplier.

Sam, twin brother of WSBK racer Alex, won't be the first English star to be given a MotoGP debut by Aprilia - the Italian factory having signed Shane Byrne, straight from BSB, in 2004.