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Hi , thanks for your reactions. I think making it myself with PPF would be the best option indeed. Any suggestions on which PPF I should get to make the protective pads?
Bikes take a huge hit to rang. Also roof box is better than bikes by a long shot. This is a picture with roof box, trailer basket and probably overloaded.This is one of the best science-driven posts I’ve read!
Has anyone done similar work with hauling a couple bikes?
As winter arrived I was excited to strap a roof rack on my Model 3 and take it to the mountains. I quickly discovered little information out there about how it would impact the range. Given the long cold uphill drive and variable weather conditions, I was determined to find the highest efficiency setup and characterize it for route planning. I started with a stock TM3 LR AWD, keeping as many variables constant as possible, and did 20+ runs up and down the highway gathering data. I tested with both the SeaSucker Monkey Bars and Tesla's Roof Rack, with various configurations of snowboards, carriers, and fairings.
Additional pictures, charts, and raw data: Model 3 Roof Rack Options - Comparing Efficiencies
TL;DR compared to stock TM3 LR AWD 18":
Test Procedure
- Tesla Roof Rack -- 1.6% range loss
- Tesla Roof Rack + Yakima FatCat 6 Evo -- 17.3% to 19.6% range loss
- SeaSucker Roof Rack + Thule 91725 Flat Top Ski Carrier -- 26.7% range loss
- Aero Wheel Caps Removed -- 5.4% range loss
I avoided traffic during the trials to not skew the data and threw out any significant outliers due to road conditions. I tried to test when the wind was at a minimum but this seemed to be the most significant variable I couldn't completely control.
- Get on the highway going 70mph with autopilot engaged and reset the trip meter.
- Drive 6.5 miles south, gaining about 130 feet in elevation.
- Log the Wh/Mi, disable autopilot, and get off the highway
- Get back on the highway going north and do the same thing again. This time losing about 130 feet in elevation.
- Average the north and south results together.
Controlled Variables
Configurations Tested
- 55-60°F outside temperature
- Dry highway road, minimal wind
- 70mph on autopilot
- HVAC off
- Radio @ 25% volume
- Tires @ 42 psi cold
- Baseline: Tesla Model 3 Dual Motor Long Range, 18” Wheels w/ Aero Wheel Caps
- Config 1: Aero Wheel Caps removed
- Config 2: SeaSucker Monkey Bars, Thule 91725 Flat Top Ski Carrier, 2 snowboards bindings down, Yakima Wildshield Fairing 46” [Picture]
- Config 3: Model 3 Roof Rack, Yakima FatCat 6 Evo T-Slot mounting, 2 snowboards bindings up (T-Slot mounts too low to put bindings down) [Picture]
- Config 4: Model 3 Roof Rack, Yakima FatCat 6 Evo standard mounting, 2 snowboards bindings down [Picture]
- Config 5: Model 3 Roof Rack, Yakima FatCat 6 Evo standard mounting, 2 snowboards bindings down, Yakima Wildshield Fairing 46”
- Config 6: Model 3 Roof Rack
Results and Real World Impact
At the end of the day I care about how much time I spend on the road. To that end I plugged the Wh/Mi figures for each config into ABetterRoutePlanner to see how they would impact the round trip driving time to my favorite ski resorts.
Wh/Mi Δ / Range Δ / Time Δ
1. No Aero Caps
+5.7% / -5.4% / +7 minutes
2. SeaSucker
+36.4% / -26.7% / +44 minutes
3. Tesla Rack + T-Slot
+24.4% / -19.6% / +28 minutes
4. Tesla Rack
+23% / -18.7% / +26 minutes
5. Tesla Rack + Fairing
+21.0% / -17.3% / +24 minutes
6. Tesla Rack Only
+1.6% / -1.6% / +2 minutes
Accuracy
For each config I did two or three round trip trials. On average the trials within a config varied by 2.2%.
Cabin Noise
I measured cabin noise for each config using the iOS app Decibel X. The absolute values are probably not too accurate, but the deltas are somewhat interesting. The baseline measured 83dB.
- Config 2 (SeaSucker) measured 84.5dB. Without the fairing the app measured lower but the sound was much more unpleasant. Likely due to the frequency of the noise and concentration at that frequency.
- Configs 3 and 4 measured 86.5dB and 86.1dB respectively. Config 5 (fairing) measured 86.7dB and was actually more unpleasant due to a small gap between the fairing and the rack+boards.
- Config 6 (Tesla Rack Only) measured 85.1dB but didn't sound too different from the baseline in practice.
Speed Impact
I repeated testing of Config 6 going 65mph instead of 70mph. The Wh/Mi decreased by 9.9%, causing the range to increase by 11.0%. No big surprises here, but always interesting to verify physics.
As winter arrived I was excited to strap a roof rack on my Model 3 and take it to the mountains. I quickly discovered little information out there about how it would impact the range. Given the long cold uphill drive and variable weather conditions, I was determined to find the highest efficiency setup and characterize it for route planning. I started with a stock TM3 LR AWD, keeping as many variables constant as possible, and did 20+ runs up and down the highway gathering data. I tested with both the SeaSucker Monkey Bars and Tesla's Roof Rack, with various configurations of snowboards, carriers, and fairings.
Additional pictures, charts, and raw data: Model 3 Roof Rack Options - Comparing Efficiencies
TL;DR compared to stock TM3 LR AWD 18":
Test Procedure
- Tesla Roof Rack -- 1.6% range loss
- Tesla Roof Rack + Yakima FatCat 6 Evo -- 17.3% to 19.6% range loss
- SeaSucker Roof Rack + Thule 91725 Flat Top Ski Carrier -- 26.7% range loss
- Aero Wheel Caps Removed -- 5.4% range loss
I avoided traffic during the trials to not skew the data and threw out any significant outliers due to road conditions. I tried to test when the wind was at a minimum but this seemed to be the most significant variable I couldn't completely control.
- Get on the highway going 70mph with autopilot engaged and reset the trip meter.
- Drive 6.5 miles south, gaining about 130 feet in elevation.
- Log the Wh/Mi, disable autopilot, and get off the highway
- Get back on the highway going north and do the same thing again. This time losing about 130 feet in elevation.
- Average the north and south results together.
Controlled Variables
Configurations Tested
- 55-60°F outside temperature
- Dry highway road, minimal wind
- 70mph on autopilot
- HVAC off
- Radio @ 25% volume
- Tires @ 42 psi cold
- Baseline: Tesla Model 3 Dual Motor Long Range, 18” Wheels w/ Aero Wheel Caps
- Config 1: Aero Wheel Caps removed
- Config 2: SeaSucker Monkey Bars, Thule 91725 Flat Top Ski Carrier, 2 snowboards bindings down, Yakima Wildshield Fairing 46” [Picture]
- Config 3: Model 3 Roof Rack, Yakima FatCat 6 Evo T-Slot mounting, 2 snowboards bindings up (T-Slot mounts too low to put bindings down) [Picture]
- Config 4: Model 3 Roof Rack, Yakima FatCat 6 Evo standard mounting, 2 snowboards bindings down [Picture]
- Config 5: Model 3 Roof Rack, Yakima FatCat 6 Evo standard mounting, 2 snowboards bindings down, Yakima Wildshield Fairing 46”
- Config 6: Model 3 Roof Rack
Results and Real World Impact
At the end of the day I care about how much time I spend on the road. To that end I plugged the Wh/Mi figures for each config into ABetterRoutePlanner to see how they would impact the round trip driving time to my favorite ski resorts.
Wh/Mi Δ / Range Δ / Time Δ
1. No Aero Caps
+5.7% / -5.4% / +7 minutes
2. SeaSucker
+36.4% / -26.7% / +44 minutes
3. Tesla Rack + T-Slot
+24.4% / -19.6% / +28 minutes
4. Tesla Rack
+23% / -18.7% / +26 minutes
5. Tesla Rack + Fairing
+21.0% / -17.3% / +24 minutes
6. Tesla Rack Only
+1.6% / -1.6% / +2 minutes
Accuracy
For each config I did two or three round trip trials. On average the trials within a config varied by 2.2%.
Cabin Noise
I measured cabin noise for each config using the iOS app Decibel X. The absolute values are probably not too accurate, but the deltas are somewhat interesting. The baseline measured 83dB.
- Config 2 (SeaSucker) measured 84.5dB. Without the fairing the app measured lower but the sound was much more unpleasant. Likely due to the frequency of the noise and concentration at that frequency.
- Configs 3 and 4 measured 86.5dB and 86.1dB respectively. Config 5 (fairing) measured 86.7dB and was actually more unpleasant due to a small gap between the fairing and the rack+boards.
- Config 6 (Tesla Rack Only) measured 85.1dB but didn't sound too different from the baseline in practice.
Speed Impact
I repeated testing of Config 6 going 65mph instead of 70mph. The Wh/Mi decreased by 9.9%, causing the range to increase by 11.0%. No big surprises here, but always interesting to verify physics.
How hard are the different racks (the ones attached to the M3 roof) to take off & put on? I personally only want the racks on part of the year for snowboarding or longish road trips and want them gone the rest of the time.
For my Inno Surf Racks, I keep the T-bolt on the racks and just remove the surf rack itself (you hardly noticed the 4 bolts sticking out from the rails). This way, it's super easy to add/remove when I need to carry surfboards.
Based on his tests, it seems using t-slot mounting point and fairing will yield the best result if you rather just keep the accessories mounted to the rack at all times.
I had to disagree because rack fairings generally INCREASE drag, not reduce it (as the provided testing shows). This is because they cause a large increase to the frontal area of the vehicle. It is possible they reduce whistling noises from attached accessories even as they increase the total drag.
But that's not what his chart shows. #4 and #5 setup are identical except his #5 configuration is with the Yakima FatCat 6 Evo rack mounted with standard mounting (not T-slot), 2 snowboards on it, with the fairing. He gained almost 1.5% efficiency from his test without the fairing with identical setup.
So based on his results, adding the fairing actually improved efficiency vs without it.
I did read it wrong on the T-slot though, and to me the I'm surprised with the results there. I guess the standard mounting for his FatCat was more efficient than mounting it with T-slots.
In my case, my rack sticks up another inch with standard mounting so I switched to a T-slot mount version.
First, 1.5% is well within the margin of error one could expect for the methodology.
Secondly, that test had snowboards mounted with the bindings facing down. This is not comparable to a rack with rack accessories left on all the time (a snowboard is a very large wing).
First, 1.5% is well within the margin of error one could expect for the methodology.
Secondly, that test had snowboards mounted with the bindings facing down. This is not comparable to a rack with rack accessories left on all the time (a snowboard is a very large wing).
Either way, with #4 and #5, all things are equal except for a fairing. If 1.5% error margin, since the 1.5% was BELOW the setup without the fairing, then it would simply mean adding a fairing doesn't affect the efficiency, not reduce efficiency as you stated.
Yea they did. I actually got the 40” first and it seemed too small, 46” seemed just right. Width wise at least, wish it was taller like my old Thule one was.