ynamic ▁fair ings . ▁ ▁Two - w heel ▁" stream lin er " ▁configurations ▁can ▁have ▁much ▁less ▁aer od ynamic ▁drag : ▁whe els ▁are ▁hard ▁to ▁make ▁aer od ynamic ; ▁each ▁wheel ▁entry / exit ▁to ▁the ▁fair ing ▁adds ▁drag ; ▁and ▁vel om ob iles ▁with ▁two ▁front ▁whe els ▁are ▁necessarily ▁wider ▁or ▁longer ▁than ▁the ▁r ider , ▁while ▁two - w heel ▁stream lin ers ▁can ▁be ▁bare ly ▁wider ▁than ▁the ▁r ider . ▁ ▁A ▁common ▁way ▁to ▁describe ▁aer od ynamic ▁drag ▁is ▁" C d A "; ▁in ▁one ▁comparison ▁of ▁racing ▁cycles , ▁there ▁were ▁several ▁two - w heel ▁stream lin ers ▁with ▁less ▁than ▁half ▁the ▁C d A ▁drag ▁of ▁the ▁best ▁three - w he eler . ▁ ▁Air ▁drag ▁is ▁most ▁significant ▁for ▁high - speed ▁events ; ▁as ▁of ▁ 2 0 1 6 , ▁the ▁world ▁record ▁for ▁a ▁ 2 0 0 - met re ▁s print ▁on ▁near - level ▁ground ▁is ▁about ▁ 1 4 5   km / h ▁for ▁a ▁two - w heel ▁stream lin er ▁and ▁about ▁ 1 2 0   km / h ▁for ▁any ▁vehicle ▁with ▁more ▁than ▁two ▁whe els , ▁meaning ▁the ▁two - w heel ▁vehicle ▁was ▁about ▁ 2 0 % ▁faster . ▁ ▁Aer od ynamic ▁power ▁is ▁roughly ▁cub ic ▁in ▁speed , ▁so ▁at ▁lower ▁spe eds ▁the ▁difference ▁is ▁much ▁less ▁pron ounced .