Aprilia have been testing a naked version of the RS457 but it's more retro than Tuono

These spy pictures give us the first look at Aprilia’s upcoming, retro-influenced naked version of their all-new twin cylinder RS457 sportsbike.

And, with the retro Aprilia featuring an all-new tubular steel frame alongside an offset shock, lone front disc, all-new bodywork, and retro-inspired round headlamp, it’s clear the new machine is much more than ‘just’ a naked version of the RS457.

The new model, clearly still in prototype, pre-production form, was spotted undergoing testing in Spain. But while certain components, such as the crudely welded, underslung exhaust and stealth black body finish, suggest it’s still some way off going on sale, details including the mirrors, numberplate hanger and lights all look good to go.

At the bike’s heart, as is clear from its identical clutch cover and cylinder design, is the same, all-new 457cc parallel twin which features in the RS457 model. That unit produces a claimed 47bhp, and, as that is right on the limit of the A2 licence categorisation, it’s unlikely to have been retuned for the naked version.

The new rear suspension design replaces the RS’s rising rate monoshock. Although the roadster’s swingarm is a little different, and now operates a single shock absorber on just the right-hand side, mounted directly between the swingarm and rear subframe.

That subframe is also new, to accommodate the bike’s longer, lower, twin saddle, as is all of the roadster’s rear bodywork and fuel tank. The front mudguard appears identical to the RS’s, however, which makes sense as both machines sport 17in wheels.

Up front the roadster’s upside-down forks appear similar to the units fitted to the RS457 (those blue arms attached front and rear are to measure suspension movement during testing and won’t form part of the completed bike), but the less-sporty roadster has only a single front disc brake in place of the RS457’s meatier twin-disc arrangement.

Finally, we can tell from the spy pictures that there are reasonably high, one-piece tubular handlebars, a TFT dash and a round, LED headlight.

We’d expect the finished version to be officially unveiled towards the autumn, with a price of around £6000.

Naked Aprilia RS457 in detail

• Identical twin: The clutch cover and cylinder shape reveals the engine to be the same 457cc parallel twin as unveiled last year at the heart of Aprilia’s all-new RS457 sportster
• Weigh to go: The new tubular steel frame could push the weight up above the sporty RS457’s 175kg (kerb). Although a lack of faring will help!
• Single-minded: Although the RS457 sportster on which it’s based has twin front discs, the new roadster just has one, although it’s still operating a radially mounted four-piston caliper
• New looks: As well as ditching the fairing, the new roadster gets a longer twin seat and new fuel tank
• Copycat clocks: The prototype roadster looks to be using the same TFT dash as the RS457 (and Aprilia’s 660s). There’s a new round headlight and taillight, both are LEDs