The 2012 End-2-End mountain bike race has reached full capacity within a week of registration opening.
The sheer volume of cyclists wanting to compete in the 46-mile challenge saw organisers increase the event's capacity to 1,700 last year.
Organiser Steve Honeybone said: ‘The level of interest is amazing but we have to cap it for the riders' safety.’
More than 650 riders will travel to the Island to compete in the race in September.
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Castletown stay four points clear atop Division 2
Rugby: Vagabonds Ladies stay top with another victory
Vagabonds men and Douglas also take respective wins on home soil
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Bacchas B take important victory in battle for top-flight safety
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It's the Manx side's heaviest ever league defeat