Shimano alivio t4000 trekking 9 speed rear mechalivio trekking rear derailleur retains the smooth shifting duo tension construction with a lower profile compared to previous models to keep the derailleur safely tucked in away from mounted pannier bags the long pulley cage allows a large gear capacity so even riding heavily loaded bikes are not a problem features speed 789 speed total capacity 45t maximum sprocket sizes 28 34t jockey wheel 11t front shifting 3 compatible with rapid