Up to €2m worth of bicycles have been stolen over the past two years, according to the latest Garda statistics.
They have been analysing 14,000 thefts around the country since 2016 and claim the thefts are becoming more common.
The average cost of a bike stolen is more than €500 and the most common time for it to be taken is between 8am and 5pm on a Friday.
Gardaí recommend spending up to 20% of the cost of the bike on two locks.
Crime Prevention Officer Tony Davis says students need to be particularly careful with their bikes.
He said: "They're stolen from all different place, but we are here in University College Cork because the academic year is just starting.
"It is not just Cork, it's all the different universities, colleges and secondary schools throughout Ireland where they are targeted by thieves."