RAGBRAI director T.J. Juskiewicz said he believes Tuesday was the busiest day in the rode's history.
Juskiewicz estimated 35,000 to 40,000 people were on bikes for the 50 mile ride from Perry to Des Moines. It is day No. 3 of a week-long bicycle ride.
"This could have been the busiest day in RAGBRAI history," Juskiewicz said. "People have a great time in Iowa. When you have beautiful temperatures, when you get day sin the 70s, tailwinds, short distance, it just makes for a good day."
Monday was an especially challenging ride of 83 miles, lots of hills and 90-plus degree heat. Riders on Tuesday were treated to a relaxing day heading into Iowa's largest city.
"It's the biggest crowd I've ever seen," Juskiewicz said. "We counted 32,000 coming into Altoona a couple years ago (in 2011). This is much bigger than that. If I had to guess, I'd say 35,000 to 40,000 people on bikes."
Ross Wilburn, of Iowa City, said the crowds were pretty spread out on the roads all though it got "uncomfortably full" on some of the hills.
"I've done 12 full weeks and four or five partial weeks, and I've not seen it this full," Wilburn said.
Juskiewicz said 70 percent of registered RAGBRAI participants come from outside Iowa's borders.
"That's a lot of tourists spending money in Iowa," he said.
Kendra O'Connor, 29, of Sacramento, CA, said there was a lot of people but it was "good energy."
"It's like the state fair in multiple places at once," she said.
Larry Anderson, 65, of Clinton, has ridden RAGBRAI at least 27 years of the 41 years in its history. He said the roads weren't too crowded, but the stopping towns were packed.
"In Dallas Center, that's one of the largest crowds I've ever seen," Anderson said.
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