More than 21,000 people are expected to gather in Otley and Pool-in-Wharfedale to watch the Tour de France.
Leeds City Council announced the estimates, along with confirmation that both communities would be part of a network of 'spectator hubs' featuring big screens, last week.
The local authority thinks some 15,000 cycling fans will head to Otley for the Grand Depart's opening day on Saturday, July 5, with another 6,000 assembling at Pool.
And the council expects a crowd of 20,000 to watch the race from Harewood House, which as well as being on the route is holding a Yorkshire Festival of Cycling over the Tour's opening weekend.
For more details about what is being planned for the first stage - which leaves from Leeds and goes through Harewood, Arthington, Pool, Otley and Ilkley before venturing into the Dales and finishing at Harrogate - visit www.leeds.gov.uk/granddepartleeds .