Having read dozens of instructions and safety guides, I can say that I have never found any speed limits published directly by the manufacturers of car bike racks.
I guess this is the case because different countries have in fact very similar speed limits. So if you play by the rules and do not drive too fast, you are going to be fine. That’s what bike rack producers probably think.
In most countries around the world, you can not drive faster than 80 mph (130 kmh). So this is basically your speed limits in case you have a bike rack installed and bikes loaded onto it. Exactly the same if you were driving without a rack.
However, there are different car bike rack types. Moreover, we should also consider this question not only from the legal perspective but from the fuel economy perspective as well.
With that being said, let’s go through each bike rack type.
How fast can I drive with a roof bike rack?
Simply do not exceed speed limits and you are going to be fine in most cases. You can definitely drive 80 mph (130 kmh), no problem. Some countries though have much higher speed limits on particular highways (for example, Germany). In this case, you’d better not exceed 80 mph (130 kmh). Not only it can be unsafe but dramatically reduce your mileage as well.
From the fuel economy perspective, driving fast with a roof bike rack installed is a bad idea. This bike rack type is known to cause the most significant mileage reduction (up to 30%). Moreover, the faster you drive, the more significant this negative effect becomes. So to speak, it is not advisable to drive faster than 65 mph (105 kmh).
How fast can I drive with a hitch bike rack?
From the legal perspective, you can not drive faster than 80 mph (130 kmh) in most countries anyway. So this is your speed limit with a hitch bike rack installed.
From the fuel economy perspective, hitch bike racks are in general less problematic than roof racks (20% less mileage in the worst-case scenario). However, even though you can technically drive as fast as 80 mph (130 kmh), I would recommend not exceeding 65 mph (105 kmh). It is especially crucial for sedans and hatchbacks since they are more affected due to the more aerodynamic form of their body.
How fast can I drive with a trunk-mount bike rack?
When it comes to this bike rack type, the rules are the same. No faster than 80 mph (130 kmh).
From the fuel economy perspective, I would not recommend driving faster than 65 mph (105 kmh). Because like any other bike rack type, trunk-mount racks do negatively affect your mileage (up to 20% reduction). The faster you drive, the more mileage reduction you are going to experience.
On top of that, trunk racks (especially cheaper models) are usually not that well made and may cause some wobbling. It will only become more pronounced at high speeds. I would not exceed 65 mph (105 kmh) even if it is allowed.
What do manufacturers say about speed limits?
How fast can you go with a Thule bike rack? What about Yakima and other producers?
As I have mentioned earlier, none of these producers specify in their instructions (or safety guides) any speed limits. It means that you can drive as fast as it is allowed on a specific road type.