Getting wet on the way to work, having nowhere to dry my clothes and having to put them back on to ride home. Yeeuch!
Fair weather cyclists hogging the showers in the summer.
Dog walkers, on the unlit section of the cycle track, dressed in black, with black dogs, in the dark.
Dog sh1t (see above).
Dog walkers with multiple dogs on those extending leads effectively blocking the track.
Cyclists who tell me off for not wearing a helmet.
Road surfaces bad enough to rattle the teeth out of your head.
Ice.
Dangerous driving.