How a vacuum cup roof rack works
A vacuum cup roof rack holds to the car with suction instead of bolts, rails or crossbars. Here is how the STAG Rack does it, and how to look after it.
The idea
The STAG Base Unit has eight 6-inch industrial grade vacuum cups. Each is rated about 200 lb of vertical and lateral grip, which gives over 1600 lb of combined pull strength. The cups sit on the roof or rear window and the base unit locks down with four Secure-Lock handles. Your sport attachment then clicks onto the base.
What it grips
Smooth surfaces without deep pores work best: glass (including Tesla roofs), fiberglass, car paint and smooth plastic. We do not recommend wrapped cars.
Safety habits
- Wipe the roof and the cups clean before every install
- Warm cups are more pliable and grip better, so do what you can to warm them before applying
- Check the cups every time you stop for gas or a break
- Take the rack off when you are not using it; it takes about 30 seconds
Tested
Every cup goes through a 48 hour suction test at our manufacturer, plus extra testing once we receive it. We have driven the rack at 100+ MPH on a closed course for testing.
Questions
How long does the suction last?
Each vacuum cup goes through a 48 hour suction test from our manufacturer, plus more testing once we receive it. When driving, check the cups every time you stop for gas or a break. Done that way, even a cross country move (one customer has done it) is no issue. Keeping the cups and the car surface clean goes a long way.
How strong are the vacuum cups?
The cups are industrial grade, rated about 200 lb of vertical and lateral grip each. Eight cups give over 1600 lb of combined pull strength, far more than anyone will need, and the rubber is gentle on your roof and paint without leaving marks.
What surfaces do the cups work on?
Smooth surfaces without deep pores: glass (including Tesla roofs), fiberglass, car paint and smooth plastic. The STAG Rack attaches to the roof or rear window.
Can I use it on a wrapped car?
We do not recommend placing the cups on wrapped cars, because the pressure from the cups could in theory cause bubbling.
How long does installation take?
Under 2 minutes. Wipe the roof and cups clean, press the base unit down, lock the Secure-Lock handles and click on your attachment. Removal takes about 30 seconds.
How fast can I drive with the rack?
We cannot legally endorse going over posted speed limits. We have driven the rack far above the limit (100+ MPH) on a closed course for testing, and it held up.
Does the rack lock to my car?
We are developing a way to lock the rack to the car. The rack goes on and off in about 30 seconds, so when you are not using it we recommend taking it off. You keep your car's looks and your fuel economy.