[bayposter]

The XTR 9100 rear derailleur uses a "cover with tongue" to reduce friction and prevent cable fraying. See page 15 in the Shimano manual and the picture below. This video shows how the cover with tongue also fits on an XT/SLX derailleur. Skip to 5:20 in the video.

This seems like a good idea. Has anyone tried using the cover with tongue on an XT/SLX derailleur and noticed a difference?

Unfortunately, the part (Shimano P/N Y5PV48000) is really hard to find right now unless you want to order one on eBay from Taiwan for about $9.00. I wonder if it's possible to cut a standard cable cap with a tongue into the same shape as the cover with tongue. Has anyone tried this? I think the shape of the cover with tongue is designed to provide more freedom of movement than a standard cable cap with a tongue.

 

[bayposter]

I think the shape of the cover with tongue is designed to provide more freedom of movement than a standard cable cap with a tongue.

Actually, I just noticed that the Shimano manual recommends an aluminum cap on the cable housing that goes into the rear derailleur on a full suspension bike. So I think that's the reason for the shape of the cover with tongue.

An aluminum cap with a tongue wouldn't work since the tongue wouldn't flex. So they designed a separate plastic tongue that can flex and abut against an aluminum cap.

 

[wschruba]

Those pieces come with the polymer wrapped cables, since it is supposed to be replaced when you change the cable.

It sits in a recess in the bottom of the hole.

 

[mevnet]

You can see it in details here -