It’s the number one question people ask about riding an electric pedal-assist bicycle – “How long does the battery last?”

Range anxiety is a common concern not just for e-bikes but for the entire segment of Electric Vehicles growing in popularity the world over. As cyclists, though, we’ve come to understand our output over the course of a ride, the fuel we need to carry, and what emergency resources we can find at convenience stores anywhere in the country. With an e-bike it seems we want assurance that the pedal-assist will be there for the entirety of the ride; we don’t want a surprise bonking from the battery. 

Googling the term finds scores of definitions on range anxiety:

Range anxiety is what an electric vehicle operator feels when the battery charge is low, and the usual sources of electricity are unavailable. It sparks a fear of getting stranded somewhere, which adds time, inconvenience, and stress to a journey.

Range anxiety refers to the fear that an electric vehicle or bike has insufficient range to reach its destination or runs out of charge whilst out, and thus leaves the occupants or rider stranded.

Nearly all of these descriptions highlight the scary term “stranded” though this seems mostly directed towards electric car operators. In a recent article about a new e-bike brand featured on the car enthusiast site Top Gear they offer this one significant difference between most EVs and e-bikes,

This bike still has pedals “to get back home the old-fashioned way”. That’s one way to beat range anxiety…

In our last post on the subject, A Look Inside Drop Bar E-Bikes, Bob Williams hinted at some of the testing he’s been doing while out riding his new(ish) e-bike. He bought one in February 2020 due in part that, “we were riding together less and less – she continued to go faster and me slower” He adds, “I’ve done a bunch of testing of pedal-assist boost levels and I find that with Boost 1 (Eco) set at 35% bring-it-on power and 40% peak that she can ride her ride and I can keep up and get a workout like normal. Hills over 10% grade do send me into Boost 2 (Sport) -though I have rarely ever used Boost 3 (Turbo)”

Bob and his wife Catherine are ride leaders with Portland Velo and have ridden with Cycle Oregon many times over the years. As part of their club leadership roles they help develop new ridership and with this reporting they offer us a look inside the finer detail of what our rides right here in Oregon will be like aboard these new machines. 

Bob Williams, his e-bike, a Garmin and Ride With GPS

I’ve done a lot of work looking at battery use based on terrain and boost level – just to get a good sense of what’s “in the tank” versus ride type. Marketing for my bike says a routine route is approximately 80 miles on a charge. I find that this number for starters is reasonably good — but use varies substantially with grade, aid, etc. Also, I’m a heavy rider so that sucks battery, too. But what I find is what I’d call a flat route, i.e. 35′ climbing/mile or less, I can actually get 100 miles of range. And after a recent firmware update I’m now getting 110?!?  The magic of algorithms I guess. 

Range is an interesting and challenging number for e-road bikes. It’s not nearly as easy to quantify as say the mileage your car gets. For instance, my Creo is marketed as having an 80mile range – or 120 miles if you have the extra 50% capacity battery that fits in the water bottle holder. For a normal Portland Velo club ride, say a 35-40 mile ride with 1,200-1,500 feet of climbing, I’ve found this to be reasonably accurate as to battery use. As a recent example I did a 38 mile, 1,825’ Washington County route which took 48% battery – a range of 79.8 miles. On the other hand, I routinely see 1% battery use per mile on really flat routes and riding normal/easy (i.e. range of 100 miles). The other extreme is 10% battery usage per mile when we were climbing an extended hill that averaged 8.7% for 4 miles out of Parkdale – so, a battery range of 10 miles under those conditions.

I started testing it in more detail using the power channel on the Garmin 1000 –which measures battery use in % left during course of ride. This is available on the Ride With GPS overview graph under the “Watts” category –the black descending line you’ll see on each chart. The Creo is set up with Boost 1 at 35%/40% peak; Boost 2 60%/60%; Boost 3 100%/100%.

Battery use – Climbing Versus Flat

Charts 1 & 2 compare a flat ride (32 ft/mile climbing) with a climbing ride (100 ft/mile). The flat ride, 39 miles, used 1.0% battery per mile – yielding a range of 100 miles. The climbing ride, 36.6 miles long, used 1.86% battery per mile –yielding a range of 54 miles. The flat ride was ridden in Boost 1 (Eco) while the climbing ride was a mix of Boosts 1 (Eco) & 2 (Sport).

Battery Use – Same Climb, Different Modes

Charts 3 & 4 looks at the same climb –2.3 miles, average grade 4.7% -using first Boost 1 for the whole climb and then Boost 3 throughout (different days). The Boost 1 (Eco) climb resulted in average speed of 8.2 mph, took 16:37 minutes and used 8% battery – or 3.5%/mile. The Boost 3 (Turbo) climb resulted in average speed of 12.8mph (56% higher) mph, took 10.38 minutes (6 minutes less) and used 18% battery –or 7.8%/mile (133% higher).

Battery Use – Paved Versus Gravel

Charts 5 & 6 look at two similarly steep routes (94’/mile climbing) with one being a mixed gravel/paved route and the other paved 100%. The mixed route used 1.72% battery/mile while the paved route used 1.6%. I was surprised that they were so close -my assumption being the gravel section would increase the battery use more.

Battery Use – Paved Versus Gravel II

Charts 7 & 8 take a second look at gravel versus paved –over similar length and average grade climbs –one on Dixie Mountain Road and the other on Larch Mountain Road–8.3 miles in length, average grade 4.1% , 1,578’ climbs. Again the differences in battery use were not substantial –2.8%/mile on the paved Larch climb and 3.0%/mile on the gravel Dixie climb. This again surprised me. Speed was slower on Dixie –7.9 mph vs 8.6 mph. I didn’t track but largely in Boost 1 (Eco) for both climbs.

What Does It All Mean?

So as you can see lots of variability in use – mostly related to climbing intensity. My sense is that stronger/lighter climbers would have less variability (i.e. use more of their own power and less pedal-assist watts since the bike has a power meter that aims to match watt usage.)

I’ve also done some comparisons of riding/climbing on gravel versus pavement. I’ve been surprised that the differential isn’t as great as I’d expected. Still more research to do on this…

Follow Bob – On The Bike and Online

So… who wants to go on a research ride with Bob? You can see more of his rides and follow along at Ride With GPS here.