Shift the bike into the smallest rear cog and smallest front chainring if applicable
Loosen the rear axle nuts or quick-release skewer
If the bike has horizontal dropouts, pull the rear wheel backward evenly
If the bike has a chain tensioner, adjust it to remove slack
Check chain slack by pressing the chain up and down at the midpoint
Keep about 1/2 inch to 1 inch of vertical movement for most single-speed bikes
Make sure the wheel stays centered in the frame
Tighten the axle nuts or quick-release skewer while holding the wheel in place
Spin the pedals and recheck chain tension
If the chain is still loose, repeat the adjustment
If the chain is too tight, move the wheel slightly forward
Lubricate the chain if needed
Inspect the chain and sprockets for wear if tension cannot be set properly