Police and highway officials have warned of the "significant dangers" of holding bicycle races on the A11 following the death of a competitor, but say they are powerless to stop the events.
The organisations say they have repeatedly highlighted the risks to bike groups, but cannot prevent the events being held because cyclists have a legal right to ride on A-roads.
The latest warning comes after the death last month of Cheryl Tye, who was taking part in a Cycling Club Breckland-organised time trial event between Croxton and Eccles when she was hit by a van.
Emergency services, including an air ambulance, were called to Roudham at around 9.40am on June 26, but the 52-year-old was pronounced dead at the scene.
The A11 dual carriageway is a popular time trialling venue for local clubs but has seen a number of collisions involving racers and drivers in recent years.
Last July another women competitor was seriously injured after being hit by a van as she took part in a time trial between Snetterton and Shropham.
National Highways said despite safety concerns, as people have a legal right to cycle on an A-road there is nothing it or police can do to stop any event.
A spokesman said: “For a number of years, we have warned the groups about the significant dangers in running time trials on major A roads. But from a legal perspective there is nothing we can do to stop them.”
It said cycle groups were issued with advice to ensure the correct guidelines are being followed including on insurance, race marshals and signage.
Norfolk police said the law requires organisers to give 28 days notice of races including date and time of the event, description of the course, number of competitors and names of officials.
It confirmed the event on June 26 had complied with the requirements.
Police and the National Highways road safety team hold twice yearly meetings with the cycle groups in the region.
Chief Inspector Jonathan Chapman said: “We are working with our partners and event organisers as the safety of all our road users remains a priority.”
Ms Tye was a keen triathlete and cyclist and member of Plomesgate Cycling Club in Suffolk.
A former member of the RAF and manager of Hadleigh Town Council, she was described as “a dynamic and determined person” by her former council colleagues who said her death was “a terrible tragedy”.
Her husband Chris, who was also taking part in the time trial, paid tribute to his wife on social media, writing “she loved doing triathlons and all sports”.
He added: “She touched everyone she came across in a positive way and will be sorely missed. She was my soulmate, a beautiful spirit and I loved the time I had with her.”
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