Shimano releases a new Ultegra rear derailleur with mountain biking clutch technology Apr 03, 2018 New Ultegra rear derailleur has mountain biking clutch technology, but does it signal Shimano's one by intent?New Ultegra rear derailleur has mountain biking clutch technology, but does it signal Shimano's one by intent? Tags: Product News Share 0 Share on Facebook Tweet Tweet on Twitter +1 +1 on Google Plus