A register is not administration on a bike ride. Groups split, punctures separate people and somebody occasionally goes home without saying so, and knowing who set off is what turns a worrying evening into a phone call.
Renewals arrive all at once. When membership and the insurance behind it run to a fixed annual date, the whole club renews in the same fortnight, and chasing that by hand consumes a committee.
Leaders are the scarce resource. Volunteers who give up a Sunday morning need rotating rather than relying on the same three people, and tracking who led what is how a club notices before somebody quietly stops.
Club kit is a group purchase with money up front. Orders have minimums, sizes are wrong for somebody and the money sits with the club for months, so it needs recording rather than remembering.