Motorist William DeWees, 78, collided with a cyclist at approximately 4:45 p.m. Thursday.
Bart Fieseler, 45, sustained internal injuries and a possible broken leg said Payson Police Commander Don Engler.
"The driver was making a left turn off Bonita (Street) onto the Beeline (Highway) southbound. The driver reported to us that due to sun glare, he didn't see the bicyclist."
Fieseler was flown to a Valley hospital for treatment. Engler said the accident is under investigation.
According to the National Highway Traffic Safety Administration, sun glare causes about 200 fatalities a year.
To prevent sun-glare accidents, Engler said use visors, wear sunglasses, slow down and proceed with caution.