Around 130 riders started off this morning on the ACT 8 Aids Ride from Olin Park in Madison and are on their way to Baraboo where they'll spend the night.
The 4-day 300-mile ride also has overnight stops in Spring Green and Albany before thy end up back in Madison for the emotional closing ceremony on Sunday.
The riders will be going through a lot of other little towns too..and you're encouraged to cheer the riders on.
Click here to find a list of cheering stations..and the approximate times the riders will be arriving.
Proceeds from the ride benefit the Aids Network in Madison. Last night more than $300,000 was raised!