In my old motocross/Enduro days, we used to (and I still do) loosen the bolts that hold the levers in place and also the handlebar mounts. Not much, but enough so you can move the levers with your hands and the bars with a stiff push.

You will need to carry the relevant spanners with you in case they become too loose with use but in the event of a crash the extra give often saves things from breaking.

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We are now retired....so....... lots of this and this and no more of this or this