It happens at the start of the final descent: one minute all is fine, the next an ominous metallic clunk precedes the machine gun rattle of a rear mech that is no longer pointing in the right direction. Closer inspection reveals the terminal nature of the failure: a 45° bend where none existed before, the cage now lining up with approximately half a dozen cassette cogs.
With modern gears design based around the finest of tolerances, the mech’s distressed state does not look as though it will get me home. In fact, it appears as though it is already flirting with a final act of martyrdom among the spokes of the rear wheel.
the mech is duly grasped, wrestled back to where it should be. And then, of course, it isn’t. Apparently brute force is not the answer and I am now confronted with two separate parts of XT derailleur and several exciting new cuts on my fingers.