SIERRA VISTA, Ariz. (AP) -- When Robert Laposta signed up to ride the 109-mile El Tour de Tucson, he had less than two weeks to train for it.

Taking on the challenge might seem a little crazy to some, but Laposta has a reason.

"A 10-year-old named Arthur (Paz) with Ewing's sarcoma," he said.

As Laposta considered signing up for the Nov. 22 race this year he found out about Ride for a Child, a new program that allows cyclists to pledge $500 or more to ride for a child from Tu Nidito.

Tu Nidito, meaning "your little nest" in Spanish, is a community-based agency that provides support to children who have a serious illness, are dealing with the death of a loved one, or who have a parent with cancer, said Ciara Meyer, assistant director for Tu Nidito.

Laposta hasn't raced before and had never ridden his mountain bike on more than 45-mile trip, but the cause was something he couldn't say no to.

Laposta recently took a trip to the Himalayan Mountains in Nepal that required full days of hiking. He decided that after that challenge, he can finish El Tour de Tucson. He knows the race will be difficult though.

"Eight and a half hours in the saddle is a challenge," he said.

But the difficulty of the race won't come close to what Arthur and other children are facing, he said.

Although the minimum requested donation is $500 for Ride for a Child, Laposta hopes to raise more than $1,000. He's already close to reaching his goal with donations from friends.

Besides raising money and participating in the race, Laposta plans to give Arthur a prayer flag he brought back from Nepal.

The Ride for a Child program has about 63 participating cyclists so far, Meyer said. The program has added significance to the race for participating cyclists.

"It has made it more meaningful," Laposta said.

This will be the 11th year Tu Nidito will be the primary beneficiary of El Tour de Tucson.

Tu Nidito is based in Tucson but serves children and families throughout southern Arizona and has a few clients who live in the Sierra Vista area, Meyer said.

The boy who Laposta is riding for, Arthur Paz, was diagnosed with Ewing's sarcoma, a rare form of cancer, when he was just a few months old. Since that time, Arthur has relapsed so many times his mom has lost count, according to Tu Nidito. Arthur, his mom and his sister, Anisia, spend more time in the hospital than at home, the organization said. Arthur has had two bone marrow transplants.

Arthur receives one-on-one support from his Tu Nidito social worker who helps him navigate and cope with his illness.

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Information from: Sierra Vista Herald, http://www.svherald.com

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