'Charity' rides always make me question how much money is actually being raised for the cause.
It's not cheap to stage a giant group bike ride.
Charity runs (as is...running on your feet) have this problem OFTEN. Where the entry fees roughly only end of covering the cost to stage the run. That's why many say the goal is to 'raise awareness' rather than 'raise money'. If they claim to be 'raising money' the IRS is going to insist that some money gets raised and donated. If they say they are going to 'raise awareness' then...well they didn't promise to give money to the cause. They just promised to draw attention to it. See the big "Run against Cancer because Cancer is bad!" banner at the Start/Finish line? That meets the legal definition of raising awareness, so there haven't defrauded anyone by promising to use the money other than as advertised.
I assume charity bike rides are similar. That many of them would raise more for the actual cause by standing on the street corner with a sandwich board just because of the lower overhead.