Through the end of June, bike thefts in Denver had risen 18% over the first six months of 2019.

The Denver Post reports that this year has seen a total of 1,621 stolen bicycles, and the recovery rate for such property is low, sitting at 9% over the past few years.

“They’re not secure, so people take them,” Denver Police Department spokesperson Jay Casillas told The Post. “There are instances where garage doors are left open and unattended. The bike is sitting right there, and it’s easy for someone to walk in and take it out.”

He added that there was no apparent reason for the increase during this time.

Cycling Weekly reports that one insurance company experienced a 45% increase in stolen bicycle claims since the onset of the pandemic.

“One of the effects of the lockdown has been so many more people buying bikes for exercise or just to get around,” David Fowkes, the head of underwriting for Admiral, told the outlet. “Several cycle retailers have reported that they’ve sold out of many models, and while this is good news for the nation’s fitness, our data suggests it’s also resulted in an increase in bicycle theft.”

Locking up bicycles and registering them with police departments are two suggested tactics for combating bike theft.