cycling

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The act, sport, or technique of riding or racing on a bicycle, motorcycle, or similar vehicle.
• adjective Relating to or used in cycling.

from the GNU version of the Collaborative International Dictionary of English.

• noun The act, art, or practice, of riding a cycle, esp. a bicycle or tricycle.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• verb Present participle of cycle.
• noun uncountable The sport of riding and racing cycles, especially bicycles.
• noun countable Any cyclic action or process
• adjective That undergoes a cyclic motion or process

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the sport of traveling on a bicycle or motorcycle