The changes seemed a bit sluggish.
I went to overtake another cyclist (who was veering all over the place and had earphones in, and had gotten their phone while they were riding to - I'm guessing - change the song - to each their own, but I personally wouldn't use earphones and I like to ride in a consistent line to communicate to others what I'm doing / where I'm going) and then my gear changes started to have no effect.
I pulled over and had a look at my bike.
Everything looked normal with the gears.
I tried to change gears and lift the seat to manually pedal forwards and for some reason it wouldn't pedal forward.
And then I put my bike down and it made a clunking sound and things seemed to shift.
I had another look and suddenly realised my quick release was undone and my back wheel was essentially loose!
I am so lucky that my back wheel didn't fall off after going over one of those gazillion speed bumps along my route to work!
[EDIT (Note from friend - Thanks Tim!): "And just to put any fears to rest, in my experience even with the back quick release fully open, it's extremely unlikely you'll ever experience a catastrophic "back wheel totally falls out" type of failure. I've gone up and down gutters a bunch of times with my back release open before noticing anything was wrong. Gear changing weirdness will always happen before wheel falls out disaster."]
SYDNEY CYCLEWAYS FREE BIKE MAINTENANCE COURSE FOR THE WIN!
The course gave me the confidence to look at the back wheel and work out what looked weird out of all those pointy bits!
I cannot say enough good things about these courses! Details here!
(image via Hyperbole & A Half)
"This man is no ordinary man. This is Mr. F G Superman. To all appearances, he looks like any other law-abiding citizen. But Mr F G Superman has a secret identity. When trouble strikes at any time, at any place, he is ready to become... BICYCLE REPAIR MAN!"