After having my XT for 35k miles (bikes got 42kmiles, 7kmiles done by previous owner) i only ever changed the cush drive rubbers once at around 36k miles.

When changed the old ones where completely done, they had very little give in them, where cracked and started to come apart.

Getting a new set made the XT feel so much more connected, like when you turn the throttle it goes there and then not a milli second later with loads of lurge.

But After 6k miles the replacement set have worn a good bit with around 5mm play in the rear sprocket and the bike started to get that feeling of play in the throttle/chain feeling again. Packed the cush drives out again with some old bicycle inner tubing and the feeling of connection is back again with in minutes (took around 20mins or so)

In Northern Ireland each set cost �4 and you need 4 so �16 for a complete change. Not that much, but when you think about it 6k miles and they are done, a rear tyre is done around this stage so you end up adding �16 on for every tyre change, i dont think so. Ok its a bit of pain to have to pack them out but i would rather do this than have that loose feeling.

What about the warrenty?

The only thing i can really see that it could possbily damage is the bearings in the rear sprocket if you get it wrong. (I done this when one of the packers moved when i placed it in and caused the rear sprocket to wobble and bust the bearing in the rear sprocket, cost around �10 to fix so nothing massive).

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Plough on