If its any consolation about 3 months ago (in my last few weeks in Reading) I was using a cheap Halfords track pump to pack up my bike tires.

The valve attachment is cheap plastic; and has to be removed from the valve in a certain way otherwise it gets stuck. I “misunderestimated” the amount of force required to remove the pump hose; and my knuckles collided into the rear cassette at speed.

For 2 weeks afterwards there were two deep cuts/scars on my hand corresponding to the tooth spacing of a 16 tooth cog…. (I left the pump behind in Reading for my cousin to use; I now have a Blackburn track pump which is far nicer and I haven’t managed to injure myself using it yet…)