Hi Ellen!
I apologize for taking so long to answer. I've been trying to get the most accurate information for you. RunDisney has had two back-to-back race weekends in January, so things have been a bit crazy and Princess Half Marathon details are just now being finalized.
What I know is that most of the runDisney buses that run to ESPN Wide World of Sports from the resorts, are charter-type passenger buses. There is room to strap a wheelchair (or stroller) on the back of most, and often they can be stored underneath the buses.
Wheelchairs ARE available at the Wide World of Sports Complex:
Wheelchairs are available for rent to guests requiring assistance. Wheelchairs are available on a first-come, first-serve basis. Wheelchairs may not be reserved and quantities are limited. Pickup and drop off location is at the ESPN Clubhouse Shop located near the Box Office. Daily price: $12.00 (with $100 refundable deposit).
If this is a situation where a scooter is required, I advise you to contact runDisney at 407-939-4786 as Princess Half Marathon weekend draws closer. You could also inquire at your resort's front desk about possible options for transportation.
Please let me know if you have any other questions!
Wheelchairs are available for rent to guests requiring assistance. Wheelchairs are available on a first-come, first-serve basis. Wheelchairs may not be reserved and quantities are limited. Pickup and drop off location is at the ESPN Clubhouse Shop located near the Box Office. Daily price: $12.00 (with $100 refundable deposit).