Shifter/Derailer Function

Test both by riding the bike, and also by having someone hold the rear wheel off the ground. Sometimes shifting can act differently under load while riding as opposed to unloaded. Check functionality of the shifting and derailer mechanisms. Ensure that the # of speeds at the shifter match those on the freewheel/cassette. Ensure that the shifter can hit each click if indexed. Gummed up shifters can sometimes be brought back to life, sometimes not. Sticky cables/housing can hamper shifter and derailer functionality.