My daughter & I have been riding a Burley Piccolo attached to my Cilo sine she was 5. (She also has a bmx type bike she's been riding without trraining wheels since 4.) I sought out the Piccolo over other similar 3rd-wheel trailers because it does have gears, figuring she might be more inclined to actually pedal up the hills if she could get into a lower gear. Her trailer has a 1x6 set-up with a gripshift. Works for her.