Tag Archives: speed

E-Bikes and range/mileage… why speed matters!

We had a customer who recently upgraded from a 20mph Class 1 e-bike to a 28mph Class 3. He was really happy about being able to easily do 24 mph on his commute now, instead of the 18 mph he’d been doing on his prior bike. But he was not happy with the “mileage” he was getting. He was expecting a “new & improved” model to have more range, and he was getting less (note that both bikes had the same 400 watt/hour battery size). Well, there’s really good reason for that.

Head to this page- https://www.gribble.org/cycling/power_v_speed.html

Using the defaults, which will be a bit off because they’re assuming the more-aero positioning on a road bike (which means a typical e-bike will actually fare worse), this is what you find-

At 18mph, it requires about 144 watts of power on level ground.
At 24mph, it requires about 300! More than double the amount of power.

Let’s say the cyclist is producing 75 watts him/herself at 18mph, and 100 watts at 24mph.

At 18mph, the bike’s motor/battery contribution is just 69 watts.
At 24mph, even with greater output from the cyclist, the motor/battery have to provide 200 watts. Nearly 3 times as much.

Even comparing a 400 watt/hour battery on the slower bike to a 500 watt/hour battery on the faster bike, the range, at 18mph vs 24mph, will still favor the slower bike.

What happens on a climb? If you’re riding with friends, no difference between the Class 1 & Class 3 bikes because A: You’re going the same speed either way, and B: At slower speeds (let’s say your friend are fit and managing 10mph on a 6% grade) air resistance is almost an insignificant factor. But this means there’s also less advantage to the more-powerful e-bike (providing you and the bike can put together the roughly 300 watts to climb that grade at that speed).

Another way of looking at this is that it’s no more difficult for an e-bike to do 10mph up a 6% grade than to go 24mph on level ground. So whatever amount of time you have on level ground at 24mph will be about the same time you’d have on climbs. Locally Kings Mtn would be an easy example, since it’s about 6% and takes about 30 minutes. You would go 12 miles in 30 minutes at 24mph, while on Kings, you’d cover 4.3 miles up, but your total range might be considered 8.6 miles because you’re coasting back down. Interesting stuff, this. I’d never thought about it until getting the email from the guy asking about the range issue on his new, more-powerful bike.

Quintana is wrong about riding on sensations / I’m blind without heart rate & power

Left & right-top, what it's like to ride "dark." Lower right, with instruments. I experienced both today.
Left & right-top, what it’s like to ride “dark.” Lower right, with instruments. I experienced both today; definitely prefer w/instruments!
No epic ride today; I took advantage of the day off to ride down to our Los Altos store and get some work done on their computers. What I didn’t expect was to find my Garmin had somehow self-discharged during the night, so I got about a quarter mile from home and my screen went dark!

My first thought was ohmygosh, if the ride’s not on Strava, it didn’t happen. And what sort of calamity might come to someone beginning something while knowing it made not even a butterfly change course? Do I go home and delay the ride until my Garmin charges? Do I snag Kevin’s Garmin and try to figure out how to make the ride download as my own? Nope. Because I’ve got the Strava app on my phone! So I spend a couple minutes syncing my power, speed and heartrate sensors to the iPhone, push the start button, put the phone in my pocket and I’m off. But the world is definitely NOT in order. The picture above tells the story.

Do I ride for fun? Yes. Do I enjoy once in a while taking it easy? So what does it matter if I don’t have screens giving me my speed, heart rate and power levels? Apparently, it matters a lot.

Riding through Woodside, Portola Valley and the Los Altos Hills, with a blank computer screen, I felt a bit lost. I knew the information was being recorded so it wasn’t as if the ride itself wasn’t happening, but I wasn’t happening. I felt a bit sluggish. Lacking in motivation. Something about not knowing how hard I was actually going, no targets or reference points, was holding me back. I tried to use other cyclists as reference points, and that helped a bit, but frankly, and ironically, it wasn’t much fun. That’s the strange thing about it… the assumption is that paying attention to heart rate & power & speed takes away from the pure enjoyment of cycling. I can see where that might be the case for some. Maybe even many. But not for me.

Arriving in Los Altos I set to work doing some long-neglected maintenance on their computers and forgot, until almost too late, to plug in my Garmin. I managed to get it up to a 12% charge, so about 1/4 of the way back, I turned it on and hoped that it would stay with me for a while. During that time I got back to that familiar feeling of knowing what I was doing and what I could be doing, which provides the motivation to push that much harder. I’m certain that, without all that data and encouragement coming from my bike’s digital dashboard, I wouldn’t have gotten a PR for the climb up Sand Hill.

No way around it, I’m addicted to my gadgets and the type of cycling they offer me. It keeps me in the game. Strava by itself is a great diary of your cycling history, and does a great job of showing your relative fitness (not to mention your gradual decline as you get older). But cycling with heart rate, power & speed right in front of you? That takes it to a whole new level.

I could never go back to the way it was, and I remember those days all too well. Stockton Time Trial, 1972 I think? 25 miles, and all I had was a stopwatch on my handlebars and mileage markers on the road. No heart monitor to tell me I was pushing too hard, too soon. No power meter to help optimize speed vs effort by changing position. No speed telling me… just that. It was agony. I survived, 2nd place even, but suffering with gadgets is a lot more fun than suffering without. For me, anyway.

Oh, the reference to Quintana? The guy who’s leading the Vuelta at the moment? The other day he said that racing would be better if power meters were banned and riders used their “sensations” to guide their efforts. I’m not buying it. Power meters may be a very small part of the reason, since they let someone know, in real time, how many matches they’re actually burning. But I think they also provide motivation and encouragement, when you know you’ve done better in the past, you know there’s a number you should be able to hit. I think, and maybe it’s wishful thinking, that there’s been a general reduction in doping so the playing field is more level than a few years ago, when doping was rampant and some riders were “super responders” who reaction more strongly to the drugs used for enhancing performance than others. Like I said, wishful thinking. –Mike–