These are the same as the orignal jockey wheels found on 9000 or 9020 series derailleurs

Stanchion diameter: 30mm

Plus it is ponytail compatible

PU foam chest pad provides additional coverage to the chest area

Sun Ringle Duroc SD37 Rim - Black - 32 Hole - 27.5 Inch Envelope Shipping These are the same asReal world riders need wheels that roll fast and are durable enough to sustain years of abuse, without costing more than the rest of the bike. SUNRingl Droc SD rims do just that. The Droc SD series is the result of real world EWS racing and good ol' fashioned downhill thrash testing. Built to last with double wall construction and welded seams, there is a tubeless ready Droc rim to suit your wheel building needs. Who's this item for: Suitable for