My dance studio has told me to wear bike shorts to class what are bike shorts exactly they said black shorts,any recommendations.

Bike shorts are skin tight and 4 to 6 inches longer than tank swim trunks. I have seen them available only at bike shops and very large sports shops, and in my opinion they are very overpriced.

Bike shorts from an actual bike shop are usually padded and yeah, VERY expensive. But that's not what you're supposed to wear. You need plain old black spandex shorts.

Poly/spandex are probably the easiest to find, and they're super cheap.
www.jcpenney.com . . .

Cotton/spandex breathes better, but they're more expensive and harder to find.
www.discountdance.com . . .
madathlete.com . . .
www.eddiebauer.com . . .