The Pan-Massachusetts Challenge Shrewsbury-Grafton Kids Ride will be held Sunday from 9 a.m. to noon at the University of Massachusetts Medical School’s satellite campus at 330 South St. The cyclists, age 15 and younger, will be raising money for cancer research through pledges they receive from family, friends, and other supporters. There are a number of routes laid out, of varying lengths and difficulty. Fun surprises and an obstacle course are along the way. The goal is to raise $15,000 overall. About 150 riders, ages 3 to 13, are expected. An after-ride party will include a barbecue, games, entertainment, and face-painting, organizers said.