Isle of Man TT: Sidecar Comeback in 2027 Only With Less Power

• More than 460 public submissions and three expert panels form the basis of the report
• Less power, reduced speed, a minimum weight and stricter scrutineering are on the table for 2027
• A final decision on whether the class will run is due in autumn 2026

On 31 July 2026 the organisers of the Isle of Man TT published the first-stage report of their Sidecar Sustainability Review. That concludes the first phase of an investigation launched after the sidecar class was halted during the 2026 TT. The report is neither a finished set of regulations nor an accident investigation. It gathers evidence, puts it in context and describes a direction. And that direction is unambiguous: the sidecars should stay, but not in the form in which they last raced.

What does the first Sidecar Sustainability Review report say?

The report concludes that there is broad support for keeping the sidecar class, but none for an unchanged return. Its finding is a credible route back into the 2027 TT schedule, tied to a package of risk-reduction measures.

The data behind it is broader than the occasion might suggest. The public call for evidence produced 472 responses. After removing blank and word-for-word duplicate entries, 465 individual submissions went into the analysis. On top of that came three panels: a competitor panel, an organisational panel and a technical panel. The authors themselves point out that the public submissions were voluntary and do not constitute a representative survey.

The four strands come from different directions but arrive at the same place. The public wants to keep the class, but ties that to the expectation of genuine reform. The competitors accept that the class is at a crossroads. The organisational panel sees a bundle of interlinked long-term problems. And the engineers consider a workable direction achievable: slower, more stable, stronger, simpler and easier to police.

Why was the sidecar class stopped at the 2026 TT?

The trigger was a series of serious crashes during practice week, after which the organisers suspended the class for the remainder of the event. A step of that kind was unprecedented.

Maria Costello and her passenger Shaun Parker crashed first, at Brandish. Costello suffered spinal injuries, according to media reports with lasting consequences. A day later the outfit of Ryan and Callum Crowe took off at Crosby and rolled over. The brothers sustained fractures and a head injury but were not in a life-threatening condition. The sequence resembled a crash involving Peter Founds and Jevan Walmsley at Rhencullen in 2025.

On 11 June 2026 the TT announced the Sustainability Review. Competitors, teams, officials and spectators were able to submit written comments until 30 June. Clerk of the Course Gary Thompson made clear at the time that this was not only about the current year, but about entry numbers, technical development and crash data spanning several years.

What role does aerodynamics play?

Aerodynamics is the most frequently named technical area of concern, but it has not been proven as a cause. The report explicitly states that there is no evidenced consensus on the direct trigger of the recent crashes.

The background is a development race over recent years. Leading teams worked on enclosed floors designed to channel the airflow under the vehicle and generate downforce. On smooth asphalt that works. The Mountain Course, however, is a public road with crests, jumps and shifting crosswinds. If the front wheel lifts, downforce can turn into lift. Floors of that kind were permitted under the regulations in force, including after the revision for 2026. Several teams had nevertheless chosen not to use them.

For 2027 the report therefore recommends only simple, verifiable requirements for bodywork and dimensions to begin with. The actual research using CAD models, simulation and practical testing is planned as a long-term programme. It is to examine lift, downforce and behaviour during pitching movements, in other words the rise and fall of the nose of the vehicle.

How much power should the sidecars have in future?

The technical panel discussed a target corridor of 95 to 100 hp, equivalent to around 96 to 101 PS (71 to 75 kW). Explicitly as a starting point, not as an agreed limit.

The experts warn against looking at power in isolation. Top speed, weight, drag, downforce, gearing, chassis geometry and handling are interconnected and have to be considered as a package. The experience of 2026 supports that caution. For last year’s event the organisers introduced a 27.5-millimetre intake restrictor. It was meant to reduce lap average speeds by around five to six km/h and cut top speed by up to 24 km/h. On the first evening Ryan and Callum Crowe nevertheless recorded a lap average of 190.3 km/h from a standing start.

These are the measures on the list for the 2027 TT

The report groups the immediate measures into a first phase that should be workable and verifiable in time for the 2027 TT. Planned are:

• a significant reduction in engine power and top speed
• tighter engine control via a spec ECU, restrictor, rev limit or an equivalent means
• gearing requirements to secure the speed limit
• a minimum weight and other simple measures for greater stability
• clearer requirements for bodywork and dimensions, including access for marshals and rescue crews
• stricter requirements for containing operating fluids
• chassis inspection, certificates for repairs and a documented technical history for every outfit
• expanded scrutineering and testing procedures
• higher requirements for qualification, recent race activity, medical fitness and professionalism

From 2027 onwards a second phase follows, with deeper development work on aerodynamics, handling, future chassis architecture and alternative engine packages. A third phase provides for a fixed review cycle. The report sums up the approach in one sentence: a return via a controlled intervention in 2027, a rebuild via evidence-based development after that.

Who sits on the review panels?

The three panels bring together active competitors, constructors, race officials and engineers from motorsport. The full line-up is listed in the report.

The competitor panel includes Ben Birchall, Pete Founds, Ryan Crowe, Todd Ellis, Steve Kershaw, Andy King, Bruce Moore, Eric Lenser, Lee Crawford and Wayne Lockey, among others. That means people involved in both of the serious crashes are part of the process. The technical panel brings together Dave Hagen as the TT’s technical director, sidecar liaison Dave Molyneux, Louis Christen of LCR Engineering, Adam and Sam Christie of CES Performance and Willem Toet of Sauber Technologies, who comes from Formula 1. Alongside Gary Thompson, the organisational panel includes deputy chief medical officer Paul Hancock, chief marshal Andy Priestley and chief technical official Trevor Denning.

More than a purely technical problem

The report places the technology in a wider picture. Falling entry numbers, the difficulty of finding passengers, a partly high average age in the field, rising costs, uneven professionalism and the condition of older chassis are described as connected issues. There is also a point the authors address openly: spectator interest and commercial demand are lower than for the strongest solo classes. That is not meant to be decisive, but it is not ignored either.

A second thought runs through the entire report. A technically ideal set of regulations that filters out most of the field would be no solution. Costs, supply chains and transition periods are therefore to be planned in. The TT also wants to develop the new format together with the ACU, with constructors and with other organisers, so that a class does not emerge which can only run on the island.

Why is less capacity alone not enough?

Because the history of the class shows that speed comes back even without a big engine. Following safety concerns in the late 1980s the TT switched to Formula Two regulations, based from 1990 on 350 cc two-strokes and 600 cc four-cylinder engines.

Even so, lap speeds kept climbing. Dave Saville recorded the first lap above a 160.9 km/h average in 1990. Dave Molyneux and Peter Hill broke the 177.0 km/h mark in 1996. Ben and Tom Birchall were the first to manage 193.1 km/h in 2023, and Ryan and Callum Crowe pushed the record to 194.8 km/h in 2025. The gains came from chassis, tyres, geometry, weight distribution, bodywork and aerodynamics. The engine rules moved along too: since 2022, 900 cc twins have been permitted alongside 600 cc fours and 675 cc triples, mainly because supersport engines were becoming scarcer and more expensive.

When will the decision on sidecars at the 2027 TT be made?

The decision is due in autumn 2026. Until then a tightly scheduled roadmap applies, which the report describes as a guideline.

In August 2026 a Technical Development Group is to be formed and to draft the package of measures. September brings discussions with competitors, constructors, the ACU and technical and medical experts. The technical assessment follows in early October, with sign-off of the package by the end of October. The final regulations are to be published by the end of November 2026, leaving teams around six months to prepare. From December to February the focus is on conversions and certification, and in spring 2027 on pre-event scrutineering and testing. A final inspection is scheduled for April 2027. The 2027 TT is set for 31 May to 12 June and looks set to become the most important date of the road racing season.

Gary Thompson describes the report as an interim step. He sets out the purpose of the investigation as follows: “The purpose of this Review has never been to decide whether Sidecars should simply return or disappear.” The report, he says, does not mark the end of the process, but the end of the first phase. The focus now lies on working with competitors, constructors, governing bodies and technical experts.

The guiding principle of the investigation is stated in the report itself: “The objective is not to build the fastest Sidecar class possible. It is to build the most sustainable Sidecar class possible.”

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