Fix a Flat

1. Remove wheel
   • Front: undo brake then wheel quick release and remove
   • Rear: shift into smallest cog in rear, undo brake then hub quick release; remove
   • Rear: set bike upside down on handlebars and seat before opening hub quick release

    

2. Deflate tire
   • Remove remaining air by depressing valve
   • Schraeder is larger, spring loaded valve and must be depressed; car style valve
   • Presta is all-metal, air sprung narrow valve; unscrew then press

    

3. Remove one side of tire from rim
   • Using tire levers, unseat one side of tire; start away from valve stem
   • For tight rim/tire combinations, multiple tire levers are needed; do not use metal levers
   • Many mountain and hybrid bikes tires will come off by hand; practice at home

    

4. Remove tube
   • Remove tube from tire; avoid valve damage by starting away from valve
   • Keep tube and tire in same relative position to each other to aid in finding puncture
   • Inspect tube for hole; mark for patching or use your spare tube for replacement

    

5. Inspect inside of tire
   • Feel inside of tire for cause of flat; use caution as cause may puncture your finger
   • Remove thorn, glass, staple, nail or whatever caused your flat
   • Inspect tire for damage caused by flat

    

6. Install new or patched tube
   • After repairing damaged tube or retrieving spare, inflate tube to give it round shape
   • Fold back tire to allow access to valve hole; insert valve first then tube into tire
   • For presta valve, screw valve closed and install valve nut loosly against rim

    

7. Reseat tire bead
   • Start reseating tire by hand at valve hole; work in both directions
   • Push valve partially back through rim to insure proper seating of tire bead
   • Visually inspect tire bead to insure proper tire seating on rim

    

8. Inflate tire
   • Inflate tire slowly, checking for bulges which might indicate improper bead seating on rim
   • Deflate if bulge occurs; carefully re-inspect and reseat bead on rim
   • Inflate to desired pressure

    

9. Install on bike
   • Front: install wheel; tighten hub quick release and attach brakes; make sure it is straight
   • Rear: install wheel by placing chain on top and bottom of small cog
   • Rear: push pulley closest to you forward; drop hub down into frame and tighten

    

10. Ride away
    • Check brake and hub quick releases; make sure that tire does not rub brakes or frame
    • Check rear derailleur to make sure that shifting is still smooth
    • If anything is wrong, the wheel is probably crooked; make sure wheels are in straight

    (Taken from the League of American Bicyclists)