During term time, when campus is full, the bike racks look normal. There are fixies and mountain bikes jostling for space. But come to campus during the holidays and you’ll see a handful of bikes around campus, baking in the sun, long abandoned by their owners. How did these misfit toys get here? Why are they still here?

Some of the bikes locked up are obvious cases. Someone has locked only their frame and one turn of a quick release later, the back wheel is gone. Evidently, a good excuse to buy a whole new bike rather than bothering to take the old one home on the train and fit a new wheel.

Some are more mysterious. Near the Chemistry building is a beautiful, powder blue road bike with a pannier rack. Its handlebars were once wrapped in cheerfully coloured tape. It also has so much rust I’m afraid to touch it, tetanus shot or not. The rear frame has disintegrated; the brakes have too. Yet prior to its long exposure, there doesn’t seem to have been anything wrong with the bike.

Campus Infrastructure Services tell me that abandoned bikes are removed during the summer holidays, but if the Chemistry bike has been around less than a year it must’ve started raining acid while I wasn’t looking. It’s not clear where the bikes go. Unlike the Australian National University, Sydney doesn’t have a recycled bike program on campus (although the Bike Doctor does fix up bikes if you need a repair).

Other bikes don’t get left behind like Lotso Bear in Toy Story 3. Instead, like Woody in Toy Story 2, they’re taken. In 2015, Campus Security had reports of 27 bikes stolen from campus. That figure is probably low, given you only need a police report to claim insurance. It’s not surprising that so many bikes are taken from campus – most locks are vulnerable to a set of $20 bolt cutters and tougher locks can be frozen off with compressed air or busted open with a car jack.

If you’d rather not lose that beautiful new fixie you spend so much time bragging about, lock it with a D-lock through the frame and rear wheel, and purchase one with a less ostentatious paint job next time – a lesson I’ve not yet learnt.