Exercising a racehorse?

ive been asked to ride 2 racehorses that belong to my dads friend. I want to now are they stronger and cheekier than regular ridng horses? ive been riding for 9 years and am very experienced i just dont want to take on horses that are 2 strong for me. im 16 and have a TB of my own but he is a regular riding horse not a racer.?