The guidelines by which MotoGP technical director Danny Aldridge decides on the legality of the new generation of downforce fairings will not change in 2018.

As a result, Aldridge - the 'sole judge' of whether aerodynamic devices are suitably 'integrated in the body streamlining' - expects designers to merge towards a similar, optimum shape.

"[The rules and guidance] will stay exactly the same. No changes. Stable, consistent and what I think you'll see is that the fairings will all morph towards a similar type of design," Aldridge told Crash.net.

"It's a hard thing to try and regulate and I understand a lot of people's opinions, saying 'those are wings'.

"But we have tried to allow the engineers some freedom to work and there are definitely pros and cons with the new fairing designs. You don't just bolt them on and go faster everywhere.

"For example, at Phillip Island, one of the slowest riders for top speed was Lorenzo with the Ducati fairing and a lot of riders chose not to use their aerodynamic fairings in Australia."

The most aggressive of the 2017 fairings was by Ducati (left in pic) which, once accepted for MotoGP use at Brno, was swiftly followed by a similar version from Aprilia at Misano (middle).

However, Yamaha then went a little too far with a prototype 2018 fairing unveiled at the Valencia test (right).

Teams can try what they like during testing, which restarts at Sepang later this month, however a new fairing design cannot be used during a grand prix weekend until it has been officially cleared by Aldridge.

That is often a back-and-forth process and it took numerous meetings and modifications before the 'at the limit' Ducati fairing was finally cleared.

For 2018, an initial start-of-season fairing plus one in-season update will be available to each rider.

However the rules also allow for some material to be removed from the fairing, meaning that a clever design can be run with differing levels of aerodynamic devices, as in the case of Ducati.

There are also no restrictions on changing the size and shape of any internal winglets, enclosed within the fairing, since the rules only apply to the 'external shape'.