The isle of man tt 2026 sidecar race will run under a new restrictor rule that cuts the inlet port dimension from 38mm to 27.5mm. The change is the biggest shift in power output for the class since 1,000cc engines were banned from the Mountain Course in 1990.
Ryan Crowe and Sulby Straight
The new plate must sit between the manifold and the throttle bodies, and the expected effect is blunt: average lap speeds could fall by three to four miles per hour, with as much as 30 seconds added to a lap. On the fastest stretches, that will be visible in the numbers first.
Ryan and Callum Crowe set the sidecar lap record at 121.021mph in 2026 after back-to-back doubles over the previous two years. Their Honda reached 163mph on Sulby Straight last year, but the new restrictions could pull that top speed down to around 150mph there.
Ben Birchall and Mark Wilkes
Ben Birchall will have Mark Wilkes beside him for the first time in 2026, giving the field another established pairing to measure against the regulation change. Ben and Tom Birchall were the first sidecar crew to break the 120mph lap barrier in 2023, a marker that now sits alongside the Crowes’ 121.021mph as the standard the new rules will try to drag back.
The class has already lived through technical resets. FIM Formula Two Sidecar regulations were introduced after 1,000cc engines were banned in 1990, allowing two-stroke engines not exceeding 350cc or four-strokes up to 600cc, and the 2026 change is being framed against that same long run of engineering shifts over the past 35 years.
Pete Founds and Lewis Blackstock
Pete Founds and Jevan Walmsley return to the entry list after missing last year following a big crash exiting Rhencullen in qualifying. Lee Crawford and Scott Hardie were third in both races last year in their absence, while Lewis Blackstock and Oscar Lawrence are listed as the first Yamaha-powered sidecar pairing in the article.
That leaves the 2026 race with a tighter technical ceiling and a familiar cast trying to adapt to it. The Crowes have the current pace advantage on paper, Birchall and Wilkes add a new partnership, and the rest of the field enters a race that should run slower, with the order likely decided by who loses the least speed under the new 27.5mm limit.
