as long as the seat post is extended or the telescoping the fold isn't effected. if it is mounted on the standard seat-post it won't go down enough to lock the bike. however it is best to not mount a loaded bag to the rack while moving the seat post because of the weight (bag can carry up to 25 pounds). the rack itself weighs next to nothing. I didn't try mounting it to the front, but i think the cables might get in the way. I will post a picture as soon as i get mine back from repairs due to a recent accident.
Last edited by ajam0153; 06-06-11 at 09:24 PM.