The Sidecar class is set to return to the Isle of Man TT in 2027 under a substantially revised rulebook. The new framework narrows the scope for technical development, raises minimum weight to 245 kg and sets the 2027 race distance at two laps. It will remain in force through 2029, giving the Race Directorate a three-year period in which to assess the direction and decide whether changes are needed.

The revision follows the cancellation of all Sidecar races at the 2026 TT after two serious incidents during practice. The review that followed addressed the class’s long-term sustainability, safety and performance control. It also examined the output of 600 cc four-cylinder engines, considered potentially excessive for three-wheeled machines, along with the need for closer control of chassis and bodywork.

A shared Sportbike foundation

Sidecar engines must now comply with the British Superbike Championship’s Sportbike regulations. The technical family includes the engines used as examples by the Aprilia RS 660, Yamaha R7 and CFMOTO 675SR-R. More important for the teams is the common development base: the change is intended to make investment planning easier while helping bring performance into a more controlled balance.

The electronics rules are being standardised as well. A single ECU and mandatory wiring structure will reduce the room for modification and give the organisers tighter control over engine output. Minimum weight rises to 245 kg, while the rules also alter the rider’s position within the bodywork: the rider’s legs may not be enclosed by the fairing.

The 2027 meeting will be the first practical test of the new formula, with the Sidecar races limited to two laps. The distance for 2028 and 2029 may be reconsidered after the 2027 event, so the initial format is not necessarily the long-term one.

A costly transition and a different Southern 100 approach

Some teams and riders have voiced reservations since the rules were issued. In certain cases, they have said the new requirements prevent them from taking part. The main difficulty is the money and time needed to rebuild existing Sidecars around a substantially different specification. The importance of safety is recognised, but the transition still creates a considerable practical burden for competitors.

The Isle of Man Department of Enterprise reiterated that the direction of the changes had been announced on 9 September, while the definitive regulations were issued on 11 November. The Southern 100, held on a different course near Castletown, is taking another route. Its Sidecar class will accept 2025-specification machines with limited modifications, including removal of the flat underside of the bodywork referred to as aerodynamic undertrays.

That difference between the two events could leave teams choosing one race or preparing two separate Sidecars. Applications for the TT open on 30 November, when the first indications of the 2027 entry will begin to emerge.