Efficiency impact with large bike on a hitch rack (results)

[awp0]

In case anyone is interested, I have some data that shows a very mild efficiency hit when carrying a (fairly large) bike on a hitch mount bike rack with a 2022 Prem AWD ER. I drove the same 130-mile route twice. The first trip was about 2 weeks ago without a bike or bike rack. The second trip was today, same route, similar traffic, about 10 degrees warmer air temp which required a little more AC, similar speed (between 65 and 70mph for the most part), carrying a large mountain bike on a Kuat NV Base two-bike rack. Both drives were mostly highway, mostly hands-free Bluecruise, and neither day seemed very windy.

First trip (Aug 23):
129.8 miles
38.1 kWh
3.4 miles/kWh
Brake score: 100% (16.1 miles added from regen)
Driving score: 81%

Second trip, with bike (Sep 4):
129.8 miles
39.0 kWh
3.3 miles/kWh
Brake score: 99% (10.9 miles added from regen)
Driving score: 88%

The bike is slightly wider than the car. I can see part of the rear tire in one side view mirror, but with the dropper post in "down" position I don't think it goes much higher than the roof line.

I was quite pleased with these results. The percentage difference in efficiency is in the single digits, which was a pleasant surprise compared to what i had read on some other forums (primarily Tesla). Maybe the difference in driving score contributed a bit, but it's hard to know how much.

One detail worth mentioning: The hitch is a Draw-Tite and I was a little surprised at how much movement the bike rack had during the drive. It wobbles a noticeable amount on uneven roads, which I'm certain is attributed to the hitch (not the rack). I've been using the same rack on our Kia Telluride with factory hitch with virtually zero movement/wobble. And yes, I'm certain that the hitch mount bolts are torqued to spec, though I'm temped to double-check that they haven't somehow loosened?

Here's the setup, but with the seat lowered:

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[Triggerhappy007]

Interesting results. I was expecting about 3.0-3.1. That looks like a nice bike, what model is that?

 

[Mach-Lee]

Most of the hitches on the Mach-E are very light duty, including the Draw-Tite. Max weight including the rack is 165 lbs. So with two big bikes like that you are probably at capacity. The metal the hitches bolt into on the Mach-E is actually the rear crumple zone, so it’s not especially robust compared to an SUV that was designed to tow. I’m not surprised it flops around a lot more.

Perhaps there is some issue with it, otherwise the hitch is probably just flimsy. The TorkLift is the strongest hitch for the Mach-E in the USA.

 

[awp0]

Interesting results. I was expecting about 3.0-3.1. That looks like a nice bike, what model is that?

Thanks, it’s an Ibis Mojo HD5.

Most of the hitches on the Mach-E are very light duty, including the Draw-Tite. Max weight including the rack is 165 lbs. So with two big bikes like that you are probably at capacity. The metal the hitches bolt into on the Mach-E is actually the rear crumple zone, so it’s not especially robust compared to an SUV that was designed to tow. I’m not surprised it flops around a lot more.

Perhaps there is some issue with it, otherwise the hitch is probably just flimsy. The TorkLift is the strongest hitch for the Mach-E in the USA.

Yeah I suspect you’re right about all of this. Makes sense. Thanks!

 

[awp0]

Btw, on the return trip yesterday it was pretty solid rain (I'd say medium intensity, but steady) with temps in the 60's. The range seemed to take a pretty big hit, dropping into the 2.9 miles/kWh territory with the bike on the rack. I didn't notice a lot of wind by looking at the trees, but it was hard to know for sure. Is a 12% range hit typical for rain? That extra inefficiency resulted in an unplanned charge stop, though I was cutting it close to begin with.

 

[MacherAWD]

Btw, on the return trip yesterday it was pretty solid rain (I'd say medium intensity, but steady) with temps in the 60's. The range seemed to take a pretty big hit, dropping into the 2.9 miles/kWh territory with the bike on the rack. I didn't notice a lot of wind by looking at the trees, but it was hard to know for sure. Is a 12% range hit typical for rain? That extra inefficiency resulted in an unplanned charge stop, though I was cutting it close to begin with.

With the rain you were probably running heat and AC if climate on Auto. Also the rain adds a lot of drag when driving. Weather takes a huge range hit...winter is coming...

 

[awp0]

With the rain you were probably running heat and AC if climate on Auto. Also the rain adds a lot of drag when driving. Weather takes a huge range hit...winter is coming...

I was careful to turn off both AC and e-heat (which for some reason always seems "on" by default even when it's hot outside). But I think it did still show that the battery spent a couple percent on climate. Every now and then I could feel the fans kick in around my feet, and it felt like it was AC cooled but I don't know for sure. Anyway, I'm thinking that most of the lost efficiency was increased rolling resistance on the wet road, and maybe some wind.

And yeah, I'm bracing for winter and a severe drop in efficiency

 

[rpowell]

Most of the hitches on the Mach-E are very light duty, including the Draw-Tite. Max weight including the rack is 165 lbs. So with two big bikes like that you are probably at capacity. The metal the hitches bolt into on the Mach-E is actually the rear crumple zone, so it’s not especially robust compared to an SUV that was designed to tow. I’m not surprised it flops around a lot more.

Perhaps there is some issue with it, otherwise the hitch is probably just flimsy. The TorkLift is the strongest hitch for the Mach-E in the USA.

why do you say the torklift is the strongest?

 

[Mach-Lee]

why do you say the torklift is the strongest?

Because it uses extra brackets that attach to the rear bumper bolts to increase tongue load capacity. Other brands of hitches don't include these brackets.

 

[awp0]

Because it uses extra brackets that attach to the rear bumper bolts to increase tongue load capacity. Other brands of hitches don't include these brackets.

If I could do it over again, I might have opted to spend the extra money on Torklift. The wobble on the Draw-Tite isn't great (though I can live with it), but the paint coating is also a little suspect. I found that it chipped and scratched very easily during installation and rust started forming quickly wherever the paint was chipped. I had to clean up the rust and use some touch-up paint to protect it, but more importantly I have concerns about how well it'll survive a New England winter. My understanding is that Torklift is stainless steel, so it would be more resistant to corrosion even if the paint chips. You live, you learn.

 

[Tampamike]

If I could do it over again, I might have opted to spend the extra money on Torklift. The wobble on the Draw-Tite isn't great (though I can live with it), but the paint coating is also a little suspect. I found that it chipped and scratched very easily during installation and rust started forming quickly wherever the paint was chipped. I had to clean up the rust and use some touch-up paint to protect it, but more importantly I have concerns about how well it'll survive a New England winter. My understanding is that Torklift is stainless steel, so it would be more resistant to corrosion even if the paint chips. You live, you learn.

I use a Kuat Rack with the the Torklift hitch. Mine moves slightly, side-to-side as well. It’s the rack, IMHO. The first time I used it was worse. I figured out that using the included Allen wrench to torque down the tensioning knob helped but didn’t totally eliminate the wobble. I checked the torque on all of the rack fasteners, as I didn’t assemble it, but everything seems tight. Seems like it just has a little inherent play in it.

 

[awp0]

I use a Kuat Rack with the the Torklift hitch. Mine moves slightly, side-to-side as well. It’s the rack, IMHO. The first time I used it was worse. I figured out that using the included Allen wrench to torque down the tensioning knob helped but didn’t totally eliminate the wobble. I checked the torque on all of the rack fasteners, as I didn’t assemble it, but everything seems tight. Seems like it just has a little inherent play in it.

I would have assumed it's the rack, but there's a noticeable difference in the wobble when I move it between our two vehicles (the other is a Kia Telluride). I'm "measuring" this just by looking at the bike through the rear view mirror while driving over uneven road. On the Telluride the bike moves extremely little, it's very solid and has been for the last two years. When I move the same rack with the same bike to the MME there's a lot more movement, almost an unacceptable amount. The knob and overall interface between rack and hitch seems secure, and I'm pretty sure it's the hitch that's flexing.

 

[Tampamike]

Is it the same hitch? the difference could be in how the rack fits into each receiver. On mine, I can move the rack from side to side a little bit and it definitely seems that the rack just moves a little. The receiver doesn’t seem to be moving, just the lateral arms of the rack.

 

[awp0]

Is it the same hitch? the difference could be in how the rack fits into each receiver. On mine, I can move the rack from side to side a little bit and it definitely seems that the rack just moves a little. The receiver doesn’t seem to be moving, just the lateral arms of the rack.

Well it's the same rack, but not the same hitch. The Telluride has a factory hitch, and the MME has a Draw-Tite aftermarket hitch. I'll take a closer look to see what's actually moving, but a very small amount of hitch/receiver flexing would translate into a larger amount of movement in the rack arms. I also just remembered that I received this little note from e-trailer in a response when I asked about a small installation problem several weeks ago:

"The manufacturers of the hitches design them so that the frame attachment arms are made of mild steel so that they can flex. "

So I wouldn't be surprised if this may be just some flex in the hitch. Tbh, I'm probably more concerned about how to prevent this from looking like a rusty mess in a couple of years (if you live in New England, you see a lot of hitches that look terrible).

 

[mkhuffman]

I took my bike on a vacation trip and just got home yesterday. It is a road bike, so it is smaller than your bike.

I was surprised how much the efficiency was hit with the bike on the back. But I guess I should not attribute all the efficiency loss to the bike, because the car was packed full of vacation stuff, my wife and two dogs. So there was a lot of extra weight as well. (Not my wife, though! Anti-weight! )

Anyway, I typically get around 2.5-2.6 mi/kWh with the cruise set on 80 mph. With the cruise set on 77 mph (wife in the car), I was getting 2.2 mi/kWh. Although the weight definitely had an impact, I think most of the loss was due to the bike.

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