The drain with a bike rack on was insane. I'm assuming this is because of the impact on drag but it was crazy. Less than half the estimated mileage. More of an fyi than anything else!
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Bike rack drain
- Thread starter TooEager
- Start date
MrBadger
Badger out
That is really concerning. I waited for the tow hitch precisely because I thought the effect on range would be less than with a roof bike rack. Surely time for a YouTuber to do some comparative testing..!
However I suppose the effect of having several bikes mounted sideways against the wind must create a bit of an air dam...
However I suppose the effect of having several bikes mounted sideways against the wind must create a bit of an air dam...
The rear ones are pretty bad I used to see mpg drop heavily on my previous Audi.
I went for the M3P so I now have a roofbars and Thule carriers, I have fitted them but not used them yet so i haven't been able to compare.
However, the drag from a bike sideways on will be greater than one facing the front I would have thought.
I also found the rear carrier meant the wheels sticking quite a long way out to the sides of the car which you had to be aware of on narrow roads.
I went for the M3P so I now have a roofbars and Thule carriers, I have fitted them but not used them yet so i haven't been able to compare.
However, the drag from a bike sideways on will be greater than one facing the front I would have thought.
I also found the rear carrier meant the wheels sticking quite a long way out to the sides of the car which you had to be aware of on narrow roads.
ckarner
Member
I move bikes with them on the roof and have not experienced much effect on range.
Jason71
Well-Known Member
That is the theory, and I am happy it's working out for you, but there are some youtube tails of woe out there that put me right off
Perhaps you could share these, I watched a number before buying and they were consistent with how I have found them.
Are you suggesting they damaged their roof?
webbah
Active Member
I’m using the OEM roof racks myself. I’d be more wary about the suction cup ones damaging the glass roof (many reports of these cracking just from flex/roll during spirited driving already). I’ve installed and removed these carefully at least 10 times to use them when required with my Thule Motion XT Large storage box. No issues at all as long as you install them according to the instructions and confirm they are fixed to the mount points. That said, I have not noticed much of a reduction of range with just the OEM racks on the car as they are aerodynamic in a sense, but I remove them when I won’t need them for awhile as I prefer the look of the car without them.
Apologies for missing the notifications. This was on the rear and at fairly slow motorway speeds like 65mph
I'm not looking forward to my first trip with our 4 bikes on the back tbh. I already used to do things like orientate saddles to face forward, remove MTB mud guards and so on, but I do wonder if it will be enough. I wondered if disrupting the air flow at the top of the back window with a small wedge would force the worst of the air up and over the bikes rather than having them in the main stream of 70mph wind? Would it help? or would it just be the same? beyond my aerodynamics knowledge.
Andrew_SE23
Member
I would have thought that the bikes create a very turbulent airflow behind the vehicle and, consequently, low pressure behind the vehicle (because the air can no longer flow in a laminar manner around the vehicle body). This means there will be a pressure drag - high pressure in front and low pressure behind - which is why it is so inefficient.
Absolutely, but can adding a wedge early in the roof line cause a smoother (and therefore more efficient) flow around the bikes. Essentially creating a low pressure zone of chaotic turbulence for them to exist in, rather than them causing such a zone. If I get time I'll try and draw some pictures later...
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