Two riders were taken to hospital after crashes during the RideLondon 100 event.
One man was in a serious condition after hitting a tree and another man was treated for a serious head injury after falling off his bike, South East Coast Ambulance Service said.
The first crash happened at 9.05am on Sunday near West Byfleet, Surrey and saw one rider airlifted to hospital whilst a second crash at 10.55am paused the RIdeLondon Classic for 25 minutes.
The course was diverted and riders in the RideLondon 100 had their route cut by 26 miles so that people would get over the finish line before the professionals finished on The Mall.
A RideLondon spokeswoman said: "Following the incident near West Byfleet when a rider required an air ambulance, a backlog of riders built up on the route.
"In order to ensure all riders get to the finish line within the required 8.5 hours, a planned diversion route has been opened at Mile 44 to divert those riders through to Mile 70 (taking out Box Hill and rejoining the route before Leatherhead).
The spokeswoman said: "The Prudential RideLondon-Surrey Classic was paused. This was done on the advice of police on the grounds of public safety due to congestion in Dorking High Street of riders in the Prudential RideLondon-Surrey 100.
"This was caused by a combination of the delay from the earlier stop when a rider required an air ambulance and other riders who were diverted at mile 44."
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