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Having been tasked with helping someone replace their tired Tourney kit, and not having come into contact with it before - I have to ask - how the hell do you get the cassette off?
Is the small cog a lockring?
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That's a freewheel, not a cassette. Freewheel removal tool in vice, locate freewheel on tool, turn wheel.
As above or use a large adjustable with the freewheel remover and turn anti clockwise.
You need one of these:
http://www.chainreactioncycles.com/shimano-freewheel-remover/rp-prod23264
Then as he said above 🙂
Ahhh, I getcha, thanks.
In fact, I have a sneaking suspicion I have one of those removal tools in my toolbox that was bought in error for a hypergilde tool years ago.... 🙂