If you'd asked me a few months back i would have said yes. They have little shield thingies which plug on the outer ends to stop crud getting in, and generally work well. However I have noticed that most of my outers have split Same with my Dura Ace cable set on t'road bike.
Interestingly both sets are grey; I notice that Shimano have moved both Dura Ace and XTr onto black outers now. Coincidence :shock: ?