Organisers are hoping for record-breaking numbers when the annual bikeathon gets underway.
Richard Knight, from the organising committee, said: "Numbers have gradually increased over the last few years and we are expecting record numbers again this year. Sunday is the last day of National Bike week and riders who have ridden before speak very highly of the event.
"We look forward to seeing more than 500 riders enjoying a fun day out."
Cyclists can choose between a 15-mile route or a 35-mile course, with the first riders due to leave the Borough Council offices in Shute End at 9.45am.
Online entry closes at midnight tomorrow (June 20) and costs £15 for adults, £5 for children between 12 and 18, and is free for youngsters under 12.
People can take part on the day, with adults paying £20, and the other prices are the same as for online entry.
The money is shared between a number of local charities including HomeStart Wokingham District - which supports families with young children - and Building for the Future, which is a parent-led charity working towards providing a community centre for disabled children.
Entrants are also welcomed to raise money for their own favourite charities through sponsorship or donations.
Everyone who takes part will receive a medal and a goodie bag.
Mr Knight said: "It is great for families or groups and is a great day out around the local countryside.
"You are free to raise money for whatever charity you want or just have a fun day out.
"Entrance fees are low and kids are free to enter. You can just pay the entrance fee and enjoy a good day out, or raise money for your favourite charity."
The rides finish at Market square and the RASPO steel band will be playing to welcome riders home between noon and 2pm.
Anyone who wants to take part should meet at the car park of Wokingham Borough Council, in Shute End.
Registration starts at 8.45am and more details are available at www.wokinghambikeathon.co.uk.