effect of bikes on mi/Kwhr.... post yours!

dtbaker61

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I thought I'd post mine from a recent out-and-back, at 80 mph on the highway, with 2 bikes on rear hitch rack....

I got 2.4 mi/kWhr on an out-and-back daytrip (no net elevation)... This same route without the rack+bikes at similar speed and outside temp would normally average about 3.0 miles/kWhr

I got home from the (142 mi day), with less than 10% charge. In fact, recharging back to 100% required 64.46 kWhr (with charge losses) .... and I have a SR battery, so that was cutting it pretty close. There were NO charge stations along that stretch of highway, so I was getting a little *concerned*.

I thought I'd post for others in planning routes and potential charge stops. This was out and back highway trip, santa fe to Las Vegas (NM) and back, so no net elevation change. The two bikes aero drag decrease my range somewhere between 10-15% !

I have SR battery, so in the future I'll plan for recharge at 100-125 miles if possible on future trips.... after reading followup posts below, I think it is safe to estimate the effect of 2 bikes on rear hitch rack as contributing to about -.5 miles / kWhr for trip planning purposes


Ford Mustang Mach-E effect of bikes on mi/Kwhr.... post yours! 20211120_ 30 MME mi-kwhr


Ford Mustang Mach-E effect of bikes on mi/Kwhr.... post yours! 20211120_ 30 MME w bikes
 
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I thought I'd post mine from a recent out-and-back, at 80 mph on the highway, with 2 bikes on rear hitch rack....

I got just 2.4 mi/kWhr
It's not "just", it's a pretty decent number. There are very many factors effecting efficiency, so the numbers can vary quite a bit. My worst at 80mph highway speed was 1.8mi/kWh and I had no bikes or anything unusual.
 
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dtbaker61

dtbaker61

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It's not "just", it's a pretty decent number.
yes, its a decent number, I just wanted to post for anybody else planning a trip with MTB on a rear hitch rack.

There are very many factors effecting efficiency, so the numbers can vary quite a bit. My worst at 80mph highway speed was 1.8mi/kWh and I had no bikes or anything unusual.
Absolutely.... highway, especially at 80mph, is way worse than around town with stop and go regen and lower speeds. I just wanted to make sure people plan accordingly and ignore the GOM

I got 1.8 one time towing my trailer with a 500# load at 80mph, one-way uphill with 2000' elevation gain over 60 miles, from Albuquerque to Santa Fe. That trip obviously is a worst case with extra weight, elevation gain AND 80 mph highway speed.
 
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I thought I'd post mine from a recent out-and-back, at 80 mph on the highway, with 2 bikes on rear hitch rack....

I got just 2.4 mi/kWhr

Significantly less than I expected. So, I thought I'd post for others in planning routes and potential charge stops. This was out and back, up into the mountains, and back, so no net elevation change. The two bikes must really affect the aero drag!

I have SR battery, so in the future I'll plan for recharge at 100-125 miles if possible on future trips.
I've had the rack since Sept and really haven't noticed a huge difference. I've taken several 100 to 150 mile RT with two bikes on at varying speed, including 80 mph for about half the distance. Maybe I'm getting around 2.8 miles/kWh down from 3.0 - 3.1.
Ford Mustang Mach-E effect of bikes on mi/Kwhr.... post yours! IMG_3301.JPEG

The real hit in range has been now that the colder weather is here (mornings below freezing and highs in the 40s or low 50s). I've seen a 10 -20% reduction in range so far. Winter is coming with cold spells where it does not get above freezing for a week or more. Have the ER battery and glad I do.
 

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Another data point: 2, 50lb e-bikes on my rack and a passenger and I was seeing 2.5 today at interstate speeds. It was also in the low 50 Fs when doing so.
 


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It's not "just", it's a pretty decent number. There are very many factors effecting efficiency, so the numbers can vary quite a bit. My worst at 80mph highway speed was 1.8mi/kWh and I had no bikes or anything unusual.
I get 1.2 to 1.6 going up the cross-island highway to get home. Without bikes. 2.4 sounds good to me. ;)
 
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dtbaker61

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Another data point: 2, 50lb e-bikes on my rack and a passenger and I was seeing 2.5 today at interstate speeds. It was also in the low 50 Fs when doing so.
Temp here was 50-60 or so, but I barely had cabin temp on . Your number was very close to mine, so that's interesting. I'll be interested to see what others post....

I may be doing that same trip in a couple weeks without a bike, and will be curious to see the difference! I am guessing that under similar temp and speed the average will be about 3.0 mi/kwhr..... so the rack w 2 bikes causing -.5mi/kwhr would be around 15% reduction in range due mostly to turbulence, although rack and two bikes probably adds up to around 150# cargo weight.
 
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I get 1.2 to 1.6 going up the cross-island highway to get home. Without bikes. 2.4 sounds good to me. ;)
... that is a pretty steep extended climb from what I remember.... what's the difference in elevation, and distance?

and more importantly, whats the average on an out-and-back trip?
 

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I've had the rack since Sept and really haven't noticed a huge difference. I've taken several 100 to 150 mile RT with two bikes on at varying speed, including 80 mph for about half the distance. Maybe I'm getting around 2.8 miles/kWh down from 3.0 - 3.1.
Ford Mustang Mach-E effect of bikes on mi/Kwhr.... post yours! IMG_3301.JPEG

The real hit in range has been now that the colder weather is here (mornings below freezing and highs in the 40s or low 50s). I've seen a 10 -20% reduction in range so far. Winter is coming with cold spells where it does not get above freezing for a week or more. Have the ER battery and glad I do.
Whats the name of that rack please? Looks pretty nice. Thanks
 

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dtbaker61

dtbaker61

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Whats the name of that rack please? Looks pretty nice. Thanks
check out 1up-usa.com
great rack.... all aluminum, very solid, and you can start with one 'tray', and add
 

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Kamuelaflyer

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... that is a pretty steep extended climb from what I remember.... what's the difference in elevation, and distance?

and more importantly, whats the average on an out-and-back trip?
The climb is about 3,000 feet or so over the course of almost 7 miles. There are short sections with a 10% grade and most of it is above 6% until near the turn. If I keep the speed down to the speed limit of 60 (this is not a freeway and is neither divided nor controlled entry), the average miles/kWh will increase by a fair bit. That's a bit hard to do as there's a mixture of traffic types including stunningly slow and rather long military convoys. After the turn towards home, the road climbs over the course of about three miles to 6000 ft (another 1,000 ft gain) then is a rolling descent for 3 more miles to our house at 4400 feet.

My lifetime average is 3.7 miles. That's just as misleading as the 1.2 miles/kWh though. That particular route is about 13 (or so) miles from home. If you decided 4% is good enough to make it home home "safely". Yeah, you'll be calling Ford or AAA. By the same token, deciding that 1.2 is all you get means you're never going anywhere.

Normal driving-wise, the car has plenty of range, we've been around the island with it on a single charge arriving at home a bit under 30%. It's just important to know what your car actually is doing under given conditions, whether that's driving up the western flanks of a very tall volcano or hauling bikes on the rook or hitch rack.
 
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dtbaker61

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The climb is about 3,000 feet or so over the course of almost 7 miles. There are short sections with a 10% grade and most of it is above 6% until near the turn. If I keep the speed down to the speed limit of 60 (this is not a freeway and is neither divided nor controlled entry), the average miles/kWh will increase by a fair bit. That's a bit hard to do as there's a mixture of traffic types including stunningly slow and rather long military convoys. After the turn towards home, the road climbs over the course of about three miles to 6000 ft (another 1,000 ft gain) then is a rolling descent for 3 more miles to our house at 4400 feet.

My lifetime average is 3.7 miles. That's just as misleading as the 1.2 miles/kWh though. That particular route is about 13 (or so) miles from home. If you decided 4% is good enough to make it home home "safely". Yeah, you'll be calling Ford or AAA. By the same token, deciding that 1.2 is all you get means you're never going anywhere.

Normal driving-wise, the car has plenty of range, we've been around the island with it on a single charge arriving at home a bit under 30%. It's just important to know what your car actually is doing under given conditions, whether that's driving up the western flanks of a very tall volcano or hauling bikes on the rook or hitch rack.

exactly why I started this thread... to get some data out to people planning trips with bike on a rear hitch rack.

At this point, I'd summarize the effect of 2 bikes on rear hitch rack, at highway speed, as -.5 mi/kWhr to be combined with 'regular' route considerations like temp and elevation.

planning a round-trip day adventure with no net elevation change is VERY different than one-way with elevation change. highways speed with no regen braking is very different than in-town with stop and go regen.
 

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I don't have a lot of data taken with bikes on, and part of the problem with the data I have is that it has a lot of confounding variables - lots of elevation gained or lost on those days, so hard to tell what the baseline should have been.

However it didn't seem like the loss in efficiency was bad - I was still out performing the ABRP estimates (when set to the default 3.1 mi/kWh), and after the fact I found that if I had tweaked ABRP to 3.4 it would have predicted very closely.

Next time I have the rack full I'll try to take some "average power at 60mph cruising speed" measurements to compare with normal driving, that should give us a good idea of the aerodynamic impact.
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