Cars get hot in the summer, and plenty of cyclists are more than happy to leave bikes and gear locked up in sweltering temperatures. But cars can get extremely hot: according to HeatKils.org, when it’s only 70°F degrees out and sunny, a car can get up to 113°F degrees within an hour. If it gets to 100°F degrees, a car can easily heat up to 172°F degrees.

Kevin Haviland, head mechanic and team manager for Norco Factory Racing, has seen his share of hot car disasters. In fact, his best advice is that if it’s hot enough that you would hesitate to leave a child or a dog in the car for any amount of time, your bike probably shouldn’t be left in the heat, either.

Here are key items of your cycling gear that you shouldn't leave cooking in your car on a hot day:

Already-Inflated Tyres

There’s a reason that Ironman races allow athletes to pump up their tyres on race morning: because overnight, heat can potentially swell an inflated tyre and cause it to explode. The same applies to any tire that’s pumped up to its max PSI in your car, says Haviland.

Bikes with Hydraulic Gear

Really, any liquid that goes on or in a bike shouldn’t be out in temperatures above 110°F degrees. Haviland points out that almost all chemicals on the bike - from the oil that keeps hydraulic brakes working to chain lubes to degreasers - all have temperatures listed on the containers, and most say to keep the liquids under 120°F degrees. After that, their efficacy goes down, and in hydraulic brakes, fluid might even evaporate.