Mounting bikes on top of PU - bad MPG hit?

[Hackker]

Since the Niagara has the built in side channel supports I thought about getting a bike rack for the top.  But figure that would probably be a pretty significant drag while towing that would impact my fuel economy.  Anyone have any real life experience with how bad it would hurt at the pump?  

I already have fork mounts in the bed of my truck, but hauling the bikes that way means I'd lost the ability to keep my hard top cover one.  Which would be nice since it offers a lot of lockable waterproof storage.  But if its going to avoid losing 2+ mpg than I can deal with it.  haha

[wavery]

Since the Niagara has the built in side channel supports I thought about getting a bike rack for the top.  But figure that would probably be a pretty significant drag while towing that would impact my fuel economy.  Anyone have any real life experience with how bad it would hurt at the pump?  

I already have fork mounts in the bed of my truck, but hauling the bikes that way means I'd lost the ability to keep my hard top cover one.  Which would be nice since it offers a lot of lockable waterproof storage.  But if its going to avoid losing 2+ mpg than I can deal with it.  haha

Just to give you an idea......a motorcycle has almost double the wind resistance of a typical passenger car.

It will be interesting to find out what you experience. However, I will tell you that it is VERY hard to figure out the difference in gas mileage in circumstances like this. There are so many elements that enter into fuel economy and it is exasperated when towing.

[mike4947]

While on the PU has less effect than on top of a TV, yes you are correct your MPG will take a hit. Your typical minivan with 4 bikes loses apx 3 MPG. The same rig with bikes on the PU drops that to apx 2 MPG.
What also effect the MPG is the TV. A large truck with a large engine will see a lot smaller effect. The added drag is a smaller percentage so it has less effect and the larger engine also shows less effect.
Same way with air conditioning in the TV. A small car will take a significant hit on MPG when running the air. Say it takes 10 HP to drive the AC. A lot more effect on a 130 HP car than on a 300 HP vehicle.
As an example my last Ranger pickup with a 4 cylinder took a 4 MPG hit when the AC was on. My currect Ranger with the 4.0L V6 and even with about 600 pounds more weight only takes a 1 MPG hit with AC.

[tlhdoc]

Towing with my Explorer I found that I loose about 3 to 4 mpg when towing with bikes on top of my TV.  On top of the PU I loose 2 to 3 mpg.  Using the Pro-Rack bike rack, which is mounted to the PU and the bikes are fork mounted I loose 1 to 2 mpg.  

[fshnfool76]

I haven't noticed any differance in MPG, so maybe I'm losing 1 or 2. The next long trip is up to Vermont in 3 weeks, I'll check it then. I know without the bikes I get 18-20 MPG on the hwy.

[curryp]

1-2 mpg of gas is worth bringing my bicycle to me. I use it so much when camping for exercise, pleasure and errand running that I probably get back close to what little extra gas I use up carting it along.