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Efficiency when carrying bikes

Discussion in 'Model S' started by docbrown, Mar 2, 2020.

  1. docbrown

    docbrown Member

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    I installed an Ecohitch on my 2018 Model S 75D a few months ago. Up until this weekend I had only used it for short trips around town, so I hadn't had any data points on how my range was affected. This weekend I did my first out of town trip carrying bikes. I was carrying 3 mountain bikes, say 30lb each, on a Saris Thelma hitch rack, which weighs about 37 pounds. Plus 3 adults.

    My range is normally 230 miles. This trip was 100 miles round trip in central Texas, so no mountains or anything. Started the trip at 100% and when I got home I was sitting at 36% battery. This means that my total range would have been about 156 miles.

    Just wondering if this kind of range hit is what other people have experienced when carrying bikes.
     
  2. dog_car

    dog_car Member

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    Yes, quite a range hit. I usually factor in a 20% decrease in range on MX 100D when carrying 2 bikes. If it is a long trip, I take off one pedal and lay them flat inside the car. Hard to do if more than 2 people.
     
  3. PianoAl

    PianoAl Member

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    I wonder if most of the range hit was from 125+ pounds of gear and three adults. The rear rack shouldn't add that much drag.

    You can experiment on ABetterRoutePlanner with different loads.
     
  4. ekendahl

    ekendahl Member

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    I don't think weight makes that much of a difference. I guess having bikes, even hanging off the rear, really screws up the AeroDynamic. I wasn't expecting such a big drop! I recently looked at a video from TeslaBjorn where someone had a small box behind their Tesla and the drop was very little. I wonder What drop do people with roof racks see?
     
  5. ReddyLeaf

    ReddyLeaf Active Member

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    This just about exactly what I experienced. S70D and 230mi—>150mi summer temperatures. There have been other threads that suggested having the bikes mounted parallel instead of perpendicular to the travel path is much more efficient.
     
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  6. BrokerDon

    BrokerDon Active Member

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    My wife and I put her M Santa Cruz Tallboy 29er and my XXL Santa Cruz Hightower 27.5" fattie inside our 2015 P85D. with both front wheels on (inside cheap Mavic wheel bags to protect our seats).. so zero range reduction. :D

    IMG_4799.JPG
     

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  7. docbrown

    docbrown Member

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    I'm jealous that you have a wife that is a serious mtb'r (judging by her bike). Btw, I have a Hightower as well.
     
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  8. cucubits

    cucubits Active Member

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    Zero range reduction here too with 2 bikes. Front wheels off but there's a chance I can tetris them with the wheels on too.
    Not ideal, had to put some cardboard/foam between them to avoid damage but it works fine.



    1.jpg
     
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  9. BrokerDon

    BrokerDon Active Member

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    You should be able to Tetris 2 bikes in with the front wheels on like we do. Just takes a bit of 3D thinking to get them in with both wheels on with cheap Mavic wheel bags on the front wheels to protect our seat backs. Trick I found was to rotate the handlebars after the front wheel got inside the hatch then angle in the frame with the rear wheel outside the hatchback until the front wheel was in place. Easier with 2 people but I've also do it alone.
     
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  10. cucubits

    cucubits Active Member

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    I will try that. Not a fan of having to take my front wheel off every time. When I put it back last night, I broke one of the pinch bolts on my Fox 36. Needless to say is that now I know the proper torque I should have put on those *facepalm*.
     
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  11. Greyworm

    Greyworm Member

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    I have a bike rack and expect to lose 10% with wind drag whenever going anywhere with it.
     
  12. rpo

    rpo Member

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    We just did an 800 mile road trip with two bikes in the back with the seats down with no problem. Could definitely fit a 3rd on top and possible a 4th.
     
  13. docbrown

    docbrown Member

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    Except then you wouldn't have room for the 3rd or 4th person in the car. Which is why I had to carry bikes on a rack in my OP.
     
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  14. LostWages

    LostWages uv has cured me

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    I'm planning on installing my hitch this weekend, planning a 1000mi road trip with 4 bikes this summer. (2 adults, 2 kids)

    I'm researching Superchargers on the route for the ability to charge without removing bikes. And planning for a pretty dramatic increase in Wh/mi, and how it effects the trip using A Better Route Planner. @docbrown your initial results were 33% loss in range. Based on your results, should I be planning for ~475 Wh/mi?
     
  15. Greyworm

    Greyworm Member

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    I think 33% is a bit much... Traveling with our electric tandem bike which probably weighs as much as 4 bikes... we lose 10%. I would expect 10-15% max.
     
  16. Ostrichsak

    Ostrichsak Active Member

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    I read 33% and I actually think it's on the low end. It has very little to do with the weight and a lot more to do with the drag it adds and how it negatively impacts the car's aerodynamics which is a significant factor when you're talking about highway speeds over long stretches. If if ambient temps are a little low and there's wind as well I could easily see it creeping up on 50% in a worst case scenario sort of situation. I've experienced nearly that myself so I can attest that with two lightweight (full carbon fiber frame 2018 models that are lighter than average) mountain bikes on the roof during temperatures that were in the 70s with a decent crosswind our efficiency dropped by nearly half.
     
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  17. A-Wimoweh

    A-Wimoweh Member

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    These aren't for everyone, but I have used the mini bomber sea sucker rack on my car with good success. I put the fork mount on the rear of the roof, just in front of the top of the tailgate. I put the sucker for the rear wheel on top of the trunk. Doing it this way keeps the bike lower, and I don't notice as much wind noise. I can also drive out of my garage with the bikes on and clear the door. It does block the view out the back window slightly, but in a way it is a benefit, cause every time I look in the rear view mirror I check on the bikes, and see if they are wobbling or whatnot. No interference with any cameras or parking sensors.
     
  18. tpoltron

    tpoltron Member

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    I just drove home a couple hundred miles from Tahoe with 2 mountain bikes on an eco hitch on our Model 3. I can’t control for all variables but we used about 1/3 more energy. It’s all about drag, not weight, and any outside bike seems to have a significant impact on these aerodynamic vehicles. Slowing down from 78 to 70 helps noticeably and is not too much of a hardship.
     
  19. cucubits

    cucubits Active Member

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    This depends on everyone's roadtrip habbits. Driving slower than all the rest of the traffic on a long trip would be a painful ordeal for me.

    Especially on the longer, more boring trips, I keep myself distracted by constantly calculating how much time I save if I drive just a bit faster. I know - this is not great, especially for roadtrips in current EVs and for shorter trips (ie. under 3-4 hours lets say) it doesn't matter.
     
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  20. tpoltron

    tpoltron Member

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    Yeah me too but the calculation you can now distract yourself with is what speed minimizes trip time in including possible charging stops.

    On my last trip the car advised me to stay below 75 to make it so I set it there. That cost me 7 minutes over my usual speed but there is no way you can do a useful supercharge that fast. On an empty V2 SpC with a low battery my LR M3 can add 60 miles of range in 6 minutes plus time to get off and on the highway.
     

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