More than 200 people have confirmed they will be taking part in the ride on Sunday, June 24, and organisers hope to exceed 500.
Richard Knight, a member of the organising committee, said: "The great thing about the Bikeathon is it is a low-entry fee and it gives riders an opportunity to raise money for their favourite charity."
Money from entry fees will be shared between local charities to be chosen by the organisers, but cyclists can also seek sponsorship for a cause of their choice.
Riders can enter individually or as a team or family, and can choose between a 15 mile route or 35 mile course.
It will start and finish from the car park by the council offices at Shute End in Wokingham.
Signing in opens at 8.45am and closes at 10.45am. The bikeathon starts at 9.45am.
Entry is £5 for children aged 12 and over. Children under 12 go free. Entry for adults is £15 in advance or £20 on the day. Each entrant will receive a goodie bag and a medal. Register at www.wokinghambikeathon.co.uk