While they all ride to cure cancer, there are as many personal reasons as there are riders.
Ian Perler of Villanova, Pennsylvania started after his father-in-law beat cancer.
"He said, you know, I want to do this bike ride, and I said, ok, I'll do it with you," he said.
They made it a yearly event for several years, until an MRI for another issue gave Ian a surprise.
"And they said, by the way, you have kidney cancer," Ian says.
Fortunately, the tumor was small, so he was able to have surgery that only removed part of his kidney.
"I now have one and three-quarter kidneys. So that's pretty good," he says.
Dr. Emily Levy is new to the Bike-A-Thon, but not to cancer.
An aunt and grandmother had breast cancer in their 40s, and a cousin had colon cancer in her 30s.
After the cousin learned she had the PALB-2 genetic mutation, Emily's mother was also tested and learned she carried the gene. Just after her 3rd daughter's birth, Emily learned she also carries the genetic mutation.
An MRI showed no sign of cancer, but at her first mammogram about a year later, devastating news.
"I had about nine centimeters of cancer in my breasts," Emily said.
What's more, "I had metastases in my nodes," she adds.
"It didn't even cross my mind that I would get breast cancer, even though I knew I had the gene. I couldn't even fathom that it would be me," she said.
After surgery, chemo, and radiation, Emily told her husband she might try cycling to help rebuild her energy.
"And he said, you know, we should sign up for this. He didn't pressure me. He knew I'd do it when I was ready," she said.
She has now dedicated her ride to ALL the young adults getting cancers once seen mostly in older people.
"It's moving so fast that I think our data hasn't even caught up," Emily says.
Ian's doctors agree.
"From what I've been told, kidney cancer at my age is not very common, but it's becoming more common," Ian says.
Ian's looking forward to that thrill of crossing the bridge again.
But whether it is someone's first ride or the 50th...
"Don't be afraid to kind of like relax and enjoy the experience!" he says.
It's not too late to sign up for the ride, or donate to teams like Ian's or Emily's.
For more information or donate or register, visit: https://secure.acsevents.org/site/STR?pg=entry&fr_id=109331