A group of 15 cyclists will attempt to ride as many laps as possible round the TT Course from midday on Saturday until midday on Sunday.
Many of them are riding to raise money for charities.
The cyclists come from the UK and many of them are riding in pairs, but there are two veteran men solo cyclists and Kirstie Harper, the first woman to ever attempt the challenge solo.
The 2016 24hr challenge builds on the success of last year’s Half Bike Heroes challenge when four men rode their folding bicycles around the Mountain Course for 24 hours. They raised over £10,190.34 for the Brain Tumour Charity.
The 37.73-mile route is set to be busy on Saturday evening as former world trials champion Dougie Lampkin is scheduled to undertake his wheelie challenge between 5pm and 8.30pm.