Disc brakes or no disc brakes? That is the question. For Specialized it’s a more important question than for most because it has committed totally to the move towards disc brakes, claiming that it might eventually phase out its rim brake bikes altogether.

‘The Tarmac has always been a pure-bred race bike,’ says Specialized’s Chris Riekert. ‘But I think when we launched the original Tarmac Disc two years ago [see a review on page 2], the disc bike was seen as a club enthusiast’s bike because you couldn’t race it.’

Since then, however, the rules have changed – both literally and figuratively – and the bike now seems to be gaining traction with pro cyclists.

Zdenek Stybar and Elia Viviani, both of Quick-Step Floors, have been competing on the Tarmac Disc this year, and Specialized has the stats to back up the pro endorsement.

If the addition of discs costs nothing in terms of weight, stiffness or aerodynamics – while offering improved braking quality – does that make the Tarmac SL6 Disc the perfect offering?

The rim brake version was certainly a bike that made an impression. At the recent Cyclist Track Day series (where visitors got to try out top-end bikes from a large number of the big brands) it was one of the most popular bikes thanks to its smooth ride, lightning acceleration and assured handling.