I see lots of discussion of range but what about headwind/tailwind?

[Dallant]

I see lots of discussion of range factors but what about headwind/tailwind?
As a windsurfer in the PNW back in the 80s, lots of folks had anemometers to measure wind speed to determine which size sail to use. Anyone factoring wind speed into their calculations? I know we’ve had lots of wind here this month and it sure makes a difference to me.

 

[AHicks]

When I talk about battery range, what MY experience is, it's generally "on average" based on a LOT of riding.

What a dealer or manf claims for battery range, maybe a lot of wishful thinking....

Headwind and tailwind just the tip of the iceberg for variables. You could add rider weight, speed (a major factor), hills, dirt vs. paved surfaces, and on and on.

 

[Tars Tarkas]

I've always seen it said that "estimated range is subject to topography, rider and cargo weight, wind, and other factors." Certainly all of these have their impacts. As far as wind is concerned, I think it would harder to come up with meaningful calculations for biking compared to windsurfing, because wind is a lot less consistent on land than on water. And on the water, every movement is wind related. On land, you ride between buildings and you change directions regardless of the wind. For the most part anyway.

Yes, wind is a factor, but it's hard to measure because of those inconsistencies. The calculus for measuring the impact on a real ride would be nearly impossible. It would be fairly easy to calculate the wind impact on a straight ride, with no wind screens, and a steady head wind, but except for a long straight beach ride, there aren't many rides like that. Unless you want to get into a lot of science and math, it might be best to stick with 'wind will help you or hurt you' depending on the direction. And a lot of bike rides are out and back, so the wind is roughly going to be a wash.

Everyone's different, but I hardly ever cut my rides so close that I need to worry about exact range. If I have doubts I carry an extra battery

TT

 

[rich c]

Sure wind makes a difference. Just like body weight, speed, gearing, assist levels, cargo weight, and grade changes. That's why when people ask about range, it's all guess work.

 

[Stefan Mikes]

Dallant: If you are making a loop ride and the wind's blowing at the same speed and from the same direction, the wind effect is cancelled re the battery range. If you, however, commute to and from work (the wind might not be the same in the afternoon as it was in the morning), the wind effect on the range is critical.

 

[Latitude]

I had a windy ride today... got off-road and into the woods as soon as I was able, did most of the ride pretty sheltered. Great tailwind on the way back on open roads! 50 km ride, still had 2 bars left (of 5) on the Purion. I don’t consider it a negative usually, when I can do this.

 

[ki11a]

The slower you go when the wind is blowing at you the less battery and motor you use because you arent fighting the wind to get faster...if that makes any sense.

So if the wind is blasting at you its best to take it a bit slower if you want to conserve battery for range.

IMO of course I have no degrees in aerodynamics or engineering...

 

[6zfshdb]

I ride mostly for pleasure on bike trails & paths. I usually ride out and back finishing at the point I started. In this case, the wind effect balances out and usually isn't a factor.

 

[BlackHand]

Dallant: If you are making a loop ride and the wind's blowing at the same speed and from the same direction, the wind effect is cancelled re the battery range. If you, however, commute to and from work (the wind might not be the same in the afternoon as it was in the morning), the wind effect on the range is critical.

This was one of the biggest surprises for me when I started commuting at the beginning of the summer. It seems like at least once or twice a week I have a 3/4 headwind going both ways on my N-S commute.

 

[Dallant]

I get that the route I take out and back likely will equalize the wind‘s effect, as I’ve experienced a ton of wind in my area since the beginning of September, this morning’s ride included. My question is there anyone who has actually attempted to include wind speeds into their own personal range equations. Just curious.

 

[Tars Tarkas]

Not me. I don't think you're ever going to have enough good data to be able to make more than essentially a guess. Are your rides calculated that precisely? Or are you planning a bike trip across the Kansas and need to know how many batteries to take or how much time you're going to spend recharging them, sure.

If I think the wind is going to make a difference one way or the other I'll change my plans or take an extra battery.

If you're okay with averages, you could figure your sail area, wind speed and direction, your average direction, and I guess the math wouldn't be that hard. There might be a calculator on the web....

I pulled a trailer across Texas into a head wind all the way and my MPG was horribly impacted. What you're talking about is real. It could just be me, but I've never felt the need to worry about this on a bike.

TT

 

[Dallant]

Not me. I don't think you're ever going to have enough good data to be able to make more than essentially a guess. Are your rides calculated that precisely? Or are you planning a bike trip across the Kansas and need to know how many batteries to take or how much time you're going to spend recharging them, sure.

If I think the wind is going to make a difference one way or the other I'll change my plans or take an extra battery.

If you're okay with averages, you could figure your sail area, wind speed and direction, your average direction, and I guess the math wouldn't be that hard. There might be a calculator on the web....

I pulled a trailer across Texas into a head wind all the way and my MPG was horribly impacted. What you're talking about is real. It could just be me, but I've never felt the need to worry about this on a bike.

TT

Again, lots of guys here are technically adept. I’m not one of them. I’m just curious if anyone was thinking about that. Feels like even a 10-15 mph headwind causes me to increase assistance at least one level, depending on incline percentage. I experienced what I’m guessing was 30 mph average a week or two ago. My normal 26.5 mile workout ride has an elevation gain of 1023 ft. The weight remains basically the same every time.

 

[Tars Tarkas]

Look at this. Headwinds I didn't carefully study the article but even though it's about analog bikes it looks like it should translate to ebikes.

I haven't been clear, I guess. What do you hope to gain if you get an answer you like? Are you planning a bike trip across the Great Prairie, or are you considering racing? You don't have to have a reason -- I'm just curious. Obviously, you aren't me, but I know about how far I can go on a battery, though not very precisely, and I have had rides I cut short because of wind, but for the kind of recreational riding I do that comes up so seldom I would never care to do the math to make an adjustment to my range expectations.

TT

 

[rdowns]

It has been very windy here lately and I feel like there has been an impact on my ride as well. Particularly since everything in my area involves a climb.

 

[Dallant]

Look at this. Headwinds I didn't carefully study the article but even though it's about analog bikes it looks like it should translate to ebikes.

I haven't been clear, I guess. What do you hope to gain if you get an answer you like? Are you planning a bike trip across the Great Prairie, or are you considering racing? You don't have to have a reason -- I'm just curious. Obviously, you aren't me, but I know about how far I can go on a battery, though not very precisely, and I have had rides I cut short because of wind, but for the kind of recreational riding I do that comes up so seldom I would never care to do the math to make an adjustment to my range expectations.

TT

I don’t really expect to gain anything but that it is something somebody here knows about.
I actually am thinking about planning a week long ride across part of the great Midwest but it’s definitely not a race. I know generally how far my Allant+7 with 500wh battery can take me on my present hilly workout route. I’ve not gotten below 2 out of 5 bars or about 40% YET. So my battery can certainly and easily get me 26.5+ on 60% and this is in very windy/hilly conditions. But I’d be carrying another battery (625wh) and a lot more gear for the kind of tour I have in mind and I’d be going from west to east which generally means the wind would be at my back. I’m just at the beginning stages of thinking about it so it’s nothing I’m committed to yet.
BTW, interesting article.

 

[BlackHand]

Again, lots of guys here are technically adept. I’m not one of them. I’m just curious if anyone was thinking about that. Feels like even a 10-15 mph headwind causes me to increase assistance at least one level, depending on incline percentage. I experienced what I’m guessing was 30 mph average a week or two ago. My normal 26.5 mile workout ride has an elevation gain of 1023 ft. The weight remains basically the same every time.

Yeah, just seat of the pants observation but my experience is about the same as yours. I've noticed the wind enough to check what it was after the ride, then the wind speed was in double digits. That will usually mean I'm working a just little harder to go about 2 mph slower and I might have a couple miles less range on my Intuvia when I get to work. Above about 15 mph wind and I probably am bumping the assist for a chunk of the commute with a greater impact on the range.

Wind at your back, extra battery, not a race - throw in some good scenery and you've got the makings of a great ride!

 

[Stefan Mikes]

I get that the route I take out and back likely will equalize the wind‘s effect, as I’ve experienced a ton of wind in my area since the beginning of September, this morning’s ride included. My question is there anyone who has actually attempted to include wind speeds into their own personal range equations. Just curious.

What I said was based on my personal experience I had gathered by daily rides of the Autumn and Winter of the year before, and of Winter and cold Spring of this year. There was no single day during that period without strong winds where I live. As I live in the flatland, there are no hills in the equation, just the wind and the speed.

What @ki11a said is very true: If you're facing headwind, the biggest mistake is to try and ride fast; it can easily cut the range by half. However, if your trip is downwind the whole time, expect significant range improvement. It really is as if you were a sail.

Yes, wind is a factor, but it's hard to measure because of those inconsistencies. The calculus for measuring the impact on a real ride would be nearly impossible. It would be fairly easy to calculate the wind impact on a straight ride, with no wind screens, and a steady head wind, but except for a long straight beach ride, there aren't many rides like that. Unless you want to get into a lot of science and math, it might be best to stick with 'wind will help you or hurt you' depending on the direction. And a lot of bike rides are out and back, so the wind is roughly going to be a wash.

Everyone's different, but I hardly ever cut my rides so close that I need to worry about exact range. If I have doubts I carry an extra battery

I liked this opinion. It is hardly possible to quantitatively estimate the effect of wind on the range. Taking a spare battery on the trip is the only way to get rid of the anxiety range.

 

[Dallant]

Just for the sake of curiosity...I’m thinking about getting a cheap anemometer and taking readings whenever I stop during a ride. Since I’m also pondering a Kiox for more info like cadence/power split/etc., this would be an interesting additional data point. It would be cool to have a small weather sensor array that would feed into a Kiox/Nyon.

 

[Alaskan]

Whenever range issues come up I always refer to the Bosch Range Assistant. The number of variables you can adjust to determine range is quite complete and included wind. It is uncannily accurate.

eBike range calculator for Bosch drive systems - Bosch eBike - Bosch eBike Systems

Use the eBike range calculator for Bosch drive systems to plan out your next ride.

www.bosch-ebike.com

The Beaufort Wind scale, developed by Sir Francis Beaufort, Royal Navy in 1805 gives common visual clues to wind velocity on land and sea.

---

On the Water​	​			On LNS
Force​	Wind (Knots)​	WMO Classification​	Appearance of Wind Effects​
0​	Less than 1	Calm	Sea surface smooth and mirror-like	Calm, smoke rises vertically
1​	1-3	Light Air	Scaly ripples, no foam crests	Smoke drift indicates wind direction, still wind vanes
2​	4-6	Light Breeze	Small wavelets, crests glassy, no breaking	Wind felt on face, leaves rustle, vanes begin to move
3​	7-10	Gentle Breeze	Large wavelets, crests begin to break, scattered whitecaps	Leaves and small twigs constantly moving, light flags extended
4​	11-16	Moderate Breeze	Small waves 1-4 ft. becoming longer, numerous whitecaps	Dust, leaves, and loose paper lifted, small tree branches move
5​	17-21	Fresh Breeze	Moderate waves 4-8 ft taking longer form, many whitecaps, some spray	Small trees in leaf begin to sway
6​	22-27	Strong Breeze	Larger waves 8-13 ft, whitecaps common, more spray	Larger tree branches moving, whistling in wires
7​	28-33	Near Gale	Sea heaps up, waves 13-19 ft, white foam streaks off breakers	Whole trees moving, resistance felt walking against wind
8​	34-40	Gale	Moderately high (18-25 ft) waves of greater length, edges of crests begin to break into spindrift, foam blown in streaks	Twigs breaking off trees, generally impedes progress
9​	41-47	Strong Gale	High waves (23-32 ft), sea begins to roll, dense streaks of foam, spray may reduce visibility	Slight structural damage occurs, slate blows off roofs
10​	48-55	Storm	Very high waves (29-41 ft) with overhanging crests, sea white with densely blown foam, heavy rolling, lowered visibility	Seldom experienced on land, trees broken or uprooted, "considerable structural damage"
11​	56-63	Violent Storm	Exceptionally high (37-52 ft) waves, foam patches cover sea, visibility more reduced
12​	64+	Hurricane	Air filled with foam, waves over 45 ft, sea completely white with driving spray, visibility greatly reduced

---

---

 

[Dallant]

Whenever range issues come up I always refer to the Bosch Range Assistant. The number of variables you can adjust to determine range is quite complete and included wind. It is uncannily accurate.

eBike range calculator for Bosch drive systems - Bosch eBike - Bosch eBike Systems

Use the eBike range calculator for Bosch drive systems to plan out your next ride.

www.bosch-ebike.com

The Beaufort Wind scale, developed by Sir Francis Beaufort, Royal Navy in 1805 gives common visual clues to wind velocity on land and sea.

---

On the Water​	​			On LNS
Force​	Wind (Knots)​	WMO Classification​	Appearance of Wind Effects​
0​	Less than 1	Calm	Sea surface smooth and mirror-like	Calm, smoke rises vertically
1​	1-3	Light Air	Scaly ripples, no foam crests	Smoke drift indicates wind direction, still wind vanes
2​	4-6	Light Breeze	Small wavelets, crests glassy, no breaking	Wind felt on face, leaves rustle, vanes begin to move
3​	7-10	Gentle Breeze	Large wavelets, crests begin to break, scattered whitecaps	Leaves and small twigs constantly moving, light flags extended
4​	11-16	Moderate Breeze	Small waves 1-4 ft. becoming longer, numerous whitecaps	Dust, leaves, and loose paper lifted, small tree branches move
5​	17-21	Fresh Breeze	Moderate waves 4-8 ft taking longer form, many whitecaps, some spray	Small trees in leaf begin to sway
6​	22-27	Strong Breeze	Larger waves 8-13 ft, whitecaps common, more spray	Larger tree branches moving, whistling in wires
7​	28-33	Near Gale	Sea heaps up, waves 13-19 ft, white foam streaks off breakers	Whole trees moving, resistance felt walking against wind
8​	34-40	Gale	Moderately high (18-25 ft) waves of greater length, edges of crests begin to break into spindrift, foam blown in streaks	Twigs breaking off trees, generally impedes progress
9​	41-47	Strong Gale	High waves (23-32 ft), sea begins to roll, dense streaks of foam, spray may reduce visibility	Slight structural damage occurs, slate blows off roofs
10​	48-55	Storm	Very high waves (29-41 ft) with overhanging crests, sea white with densely blown foam, heavy rolling, lowered visibility	Seldom experienced on land, trees broken or uprooted, "considerable structural damage"
11​	56-63	Violent Storm	Exceptionally high (37-52 ft) waves, foam patches cover sea, visibility more reduced
12​	64+	Hurricane	Air filled with foam, waves over 45 ft, sea completely white with driving spray, visibility greatly reduced

---

---

If only I had waves to judge by! I used to watch the waves when I was sailboarding and I had a good friend who was a sailboarder/meteorologist and always brought an anemometer with him.
Seriously, they do make some fairly cheap anemometers if I get serious enough about it. I’ve seen and used that Bosch calculator and I do like it.