Do cargo cross bars decrease range?

[Edschwartz1]

Hey Gang, love my R1S quad! We Frequently make 250 mile trips and wondering if I should worry about losing range due to cross bars. Anybody have experience or insight? Should we take them off when not in use and longer trips? Thanks.

Sponsored

 

[Scoiatael]

I never had the cargo bars myself, but I remember seeing some videos a few years ago and it was like a 0.01 kwh difference. It was pretty negligible from what I remember.

 

[SANZC02]

I always took mine off of any vehicle when not using them. Cuts down on wind noise from the roof and does help with range. I purchased them for my R1S but only put them on when using them.

Here is an old test, it is for an ICE vehicle but the princible is the same. In my experience the more noise generated by them the more effeciency being lost.

 

[VSG]

Yes of course you lose range. The only question is how much. 5% or more would be pretty typical for a SUV.

But it is so very easy to take the Rivian cross bars on and off that there is no need to leave them on all the time, unless you just really really like the look and are willing to "pay" for that in range.

 

[wicked2112]

Anything you mount that isn't blade thin will decrease range. Cargo bars will not kill your overall range on trips or daily use. Should be fine!

 

[jeeden]

Yes of course you lose range. The only question is how much. 5% or more would be pretty typical for a SUV.

But it is so very easy to take the Rivian cross bars on and off that there is no need to leave them on all the time, unless you just really really like the look and are willing to "pay" for that in range.

5% is definitely too much (that would be like 15 miles of range on a full charge). A lot of people on the internet have logged their efficiency with the cross bars and with roof boxes and even with the largest roof box that is somewhat aerodynamic it is 3% MAX. Just the cross bars is almost in calculable. As mentioned above, the real reason to take them off when not using them would be looks and noise (although elsewhere on this forum someone solved the whistling issue with 3d printed shims)

On our R1S it is about a 7 mile hit on a full charge to have the cross bars and our roof box on for all highway 70+mph driving. Less than 1 mile for just roof bars.

It's important to remember that the Rivians aren't exactly streamlined butterflies to begin with so it isn't like your going from this super aerodynamic vehicle to one with all sorts of wind resistance because of cross bars.

 

[White Shadow]

Yes of course you lose range. The only question is how much. 5% or more would be pretty typical for a SUV.

But it is so very easy to take the Rivian cross bars on and off that there is no need to leave them on all the time, unless you just really really like the look and are willing to "pay" for that in range.

5%? Nah....I'd be shocked if it's even 1%.

 

[Edschwartz1]

Thanks for the insights. I do like the look so I will probs put them on for daily drive and remove them for trips, mostly to reduce noise.

 

[VSG]

5% is definitely too much (that would be like 15 miles of range on a full charge). A lot of people on the internet have logged their efficiency with the cross bars and with roof boxes and even with the largest roof box that is somewhat aerodynamic it is 3% MAX. Just the cross bars is almost in calculable. As mentioned above, the real reason to take them off when not using them would be looks and noise (although elsewhere on this forum someone solved the whistling issue with 3d printed shims)

On our R1S it is about a 7 mile hit on a full charge to have the cross bars and our roof box on for all highway 70+mph driving. Less than 1 mile for just roof bars.

It's important to remember that the Rivians aren't exactly streamlined butterflies to begin with so it isn't like your going from this super aerodynamic vehicle to one with all sorts of wind resistance because of cross bars.

You know there have been a lot of actual studies of this over the years? Done by people other than random dudes on the internet who give us vague numbers from their uncontrolled and unscientific tests.

5% is a reasonable number. Even a simple google search will show that.

 

[jeeden]

You know there have been a lot of actual studies of this over the years? Done by people other than random dudes on the internet who give us vague numbers from their uncontrolled and unscientific tests.

5% is a reasonable number. Even a simple google search will show that.

You're right.... and if you read those studies you would know it is highly dependent on the platform, the stock aerodynamics of the vehicle, and that they have found the mileage hit to be as low as 1%-2% and as high as 10%-15%.

In the case of the Rivian which is not very aerodynamic to begin with (which is why with a battery so much larger than a Tesla it doesn't get equally better range) it is pretty negligible, as it is with most SUVs.

There is no way that the cross bars on a Rivian cost it 30 miles at full range.

 

[SANZC02]

You're right.... and if you read those studies you would know it is highly dependent on the platform, the stock aerodynamics of the vehicle, and that they have found the mileage hit to be as low as 1%-2% and as high as 10%-15%.

In the case of the Rivian which is not very aerodynamic to begin with (which is why with a battery so much larger than a Tesla it doesn't get equally better range) it is pretty negligible, as it is with most SUVs.

There is no way that the cross bars on a Rivian cost it 30 miles at full range.

I think the Rivian is more aerodynamic than people think, not as low as sedans but for a big brick pretty decent.

R1S .28

R1T .30

 

[racekarl]

I think the Rivian is more aerodynamic than people think, not as low as sedans but for a big brick pretty decent.

R1S .28

R1T .30

Drag coefficient isn't the problem for something like the R1, it's drag area. The shape may be "slippery" but it still has a large frontal area and may be a relatively high-drag vehicle overall.

 

[SANZC02]

Drag coefficient isn't the problem for something like the R1, it's drag area. The shape may be "slippery" but it still has a large frontal area and may be a relatively high-drag vehicle overall.

Not sure I understand your point here, can you explain a bit more?

Drag coefficient is a number calculated by the drag being created, is that not similar to comparing a pound of steel to a pound of feathers? It seems you are suggesting the drag coefficient is based on something other than the number. I have never heard that and understood it to be a more like a level of effort to displace whatever fluid, in the case of a vehicle that would be air. Outside of the drag coefficient there are other things determining efficiency like vehicle weight, tire resistance, and mechanical efficiency but the drag rating should be a direct comparison to other vehicle ratings.

 

[racekarl]

Not sure I understand your point here, can you explain a bit more?

Drag coefficient is a number calculated by the drag being created, is that not similar to comparing a pound of steel to a pound of feathers? It seems you are suggesting the drag coefficient is based on something other than the number. I have never heard that and understood it to be a more like a level of effort to displace whatever fluid, in the case of a vehicle that would be air. Outside of the drag coefficient there are other things determining efficiency like vehicle weight, tire resistance, and mechanical efficiency but the drag rating should be a direct comparison to other vehicle ratings.

Drag coefficient is essentially a measure of how aerodynamically efficient a shape is. Drag area includes that efficiency multiplied times the frontal area.

From Car and Driver:
"Drag Area: The product of the drag coefficient and frontal area is the best measure of any car’s aero performance because it’s directly proportional to the horizontal force measured in a wind tunnel and experienced on the road."

A small aerodynamically inefficient car (high Cd) could have less aerodynamic drag overall than a large, aerodynamically efficient vehicle like the R1.

 

[Tarkus]

Guess I'll find out for myself in about 2 months or so as I buy a set so I can mount the SunGo Rooftop folding solar charger in about 6 months or so...

Sponsored