The Isle of Man TT will complete its move from Supertwin to full Sportbike regulations at the 2027 event. The change closes out 14 years of racing for a class formerly known as the Lightweight TT and finishes a phased process that began in 2024. Sportbike-specification motorcycles will still compete alongside the existing Supertwins at the 2026 TT, before the new framework becomes the class’s exclusive rule set from 2027.

A rulebook shared with national racing

From 2027, the Sportbike TT’s technical regulations and Balance of Performance rules will mirror those of the British National Sportbike Championship. That gives teams continuity between short-circuit and road-racing calendars, instead of requiring them to start from scratch for the TT. The event still imposes its own demands through a 37.73-mile course. Teams will therefore be allowed to modify fairings and the frontal area to improve wind protection across the long, high-speed sections, following an approach already used in Superstock.

Cost is a central part of the decision. Compared with the Superbike and Supersport categories, the relatively open Supertwin rules offered substantial engineering freedom. They also encouraged bespoke, limited-run motorcycles and expensive development. According to the organizers, the tighter Sportbike framework and its Balance of Performance system are intended to reduce the advantage gained through heavy spending on technical development while allowing different engine configurations to be balanced.

Ed Wilson, Head of Sport, said the specialist development involved had made cost a significant barrier to participation and could have a major effect on competitiveness. Technical Director Dave Hagen said Balance of Performance should produce a more level playing field, with preparation and rider performance carrying greater influence on the result. Organizers also link Sportbike’s commercial relevance and the ability to balance performance with direct involvement from several major manufacturers, while engagement with Supertwin had declined. The Sidecar class is set to make a similar change, moving from its previous 600cc inline-Four engines to Sportbike-class engines and Balance of Performance rules. Full 2027 TT technical regulations will be released in November 2026.