The low end mtn. bike I bought a while back has the Shimano Tourney stuff. It works okay for my needs, but frequently the rear derailleur, with its big ol red pulley, grabs a piece of vine or something, and binds itself up. Would a derailleur with a smaller pulley, and generally less gangly arm, be less likely to grab foliage? Or should I just try to avoid weeds? Why the big ol pulley on this cheap RD anyway? For that matter, why red? I'm thinking of getting maybe a Deore or something (This is a 7 speed).