I've been following a conversation about eBikes occurring over at https://theconversation.edu.au/electric-bikes-at-250-watts-the-view-has-opened-up-nicely-10465 and seeing a pretty interesting stream of comments rolling in, with the full spectrum of inspirational stories through to trenchant trolling and cynicism. I was curious to see the cynics observing that there was no way an ebike would provide an observable benefit to fitness, nor make much of a demand upon a rider for effort. Having a background in exercise science meant that it was time to gather some data and bring some evidence into The Conversation. I know just how hard I work riding off-road, so thought it was time to back this up with a little rigour.
I've done three tests now under reproduced conditions - standardising clothing (smart business clothes, flat shoes), weight of extras (bike lock, helmet), terrain (5km local off-road loop with a steady sustained climb, noting that 5-10km is an ideal car-replacement ride distance) and varying only the bike with the following changes:
Test 1: Unpowered mountain bike (PACE RC200 - my old race bike converted to commuter duties)
Test 2: Stealth Fighter @200w limit, with a 40km/h limited hi-torque motor
Test 3: Stealth Fighter @3kw, with the same motor
For each test, I used Strava (http://www.strava.com) to track my HeartRate, speed, elevation and overall ride length, with a Wahoo Fitness BlueHR heart monitor hooked up (yes, we sell them). For each test, Strava generates a nice plot of elevation, speed and heartrate, which I've included in the result sets. Across all results, I've highlighted the highest values in red.
Note: I'm 44, so have a theoretical maximum heart-rate of 176bpm (using the least objectionable formula of HRmax = 205.8 − (0.685 × age) listed at http://en.wikipedia.org/wiki/Heart_rate). For an indication of the intensity of riding effort used based on average and maximum HeartRates, I've included the following guide:
Standard MTB 5km Loop
Strava Plot for Test 1, based on unpowered mtb on 5km test circuit.
Heart Rate: Avg=167 Max=182
AvgHR % of (theoretical)Max:
Max Speed: 55.8km/h
Avg Speed: 23.1km/h
Stealth Fighter @200w 5km loop
Strava Plot for Test 2, based on 200w limited Stealth Fighter eBike on 5km test circuit.
Heart Rate: Avg=158 Max=171
AvgHR % of (theoretical)MaxHR: 90%
(1m13s quicker over 5km than Test1)
Max Speed: 47.9km/h
Avg Speed: 25.2km/h
StealthFighter @3kW 5km loop
Strava Plot for Test 3, based on Stealth Fighter eBike running at 3kw on 5km test circuit.
Heart Rate: Avg=157 Max=172
AvgHR % of (theoretical)MaxHR: 89%
4m29s quicker over 5km than Test1
3m16s quicker over 5km than Test2
Max Speed: 49.8km/h
Avg Speed: 36.2km/h
Yes, I can get a great workout on an eBike - in Tests 2 and 3, I was within 1bpm average sustained at a fairly level output throughout the ride, working at 85%MaxHR or higher, but not as high as I have to when riding unpowered (see Test 1).
Test 2 and 3 showed negligible difference in peak speeds on a downhill section of this 5km loop, but a marked difference in average speed. This is a clear demonstration that the average speed is most impacted by the use of power when climbing, which is the sort of terrain where the benefits of an eBike are most noticable and where maximum assistance is provided. To see the magnitude of difference, look at average speeds in the 2-3.5km stage of the ride.
Interestingly, I was fastest on the test loop downhill on my old MTB.
Also interesting was that I was only marginally faster in terms of average speed on a 200w limited eBike over 5km than I would have been if I'd stayed unpowered on my old bike. However, I'd have taken 4min20s longer to arrive at my destination than if I'd been allowed to use a speed limited eBike of higher output. By the time you extrapolate that out to a longer trip of 5-15km, clearly the gap in elapsed commute time would start to stretch out further.
Also consider that these tests were done unladen - in commuting practice, I usually need to also be carrying a backpack with food, laptop - spare shoes/clothing if I'm unpowered, as I'd ride in cleats - to a range of different destinations. As a consultant, my workplaces are a little more diverse and transient than a standard 9-5 role. The role of power-assisted riding when dealing with a load, especially when climbing, should be considered in that.
Now that the Hunter EV Festival is all done and dusted for 2012 and we're back into the swing of daily business and the demands of the IT Consulting day job, I've had some time to reflect on the festival and lots of conversations held whilst we were there demonstrating. Before I get into the details of it though, I've been checking out some of the stuff coming out of Interbike 2012 (where Stealth Electric Bikes will be attending and demonstrating - see their nice white Bomber at left), including this moped redux from GasBikes in the USA (below left).
I'd made the point during a brief interview with 1233 ABC Newcastle that this is exactly the kind of stuff being built in sheds all around the country, by backyard tinkerers and kids looking for some easy speed, with some real frankenbikes getting churned out that I don't think I'd throw a leg over anytime soon. I'd also mentioned during that interview that people could make a brief visit to Campbells Store in Morpeth to check out the museum section there and have a glance at an old Malvern Star petrol powered Auto-Byke (pictured below right, circa 1950).
Note the similarities between the two, with the superior standover height, low CoG and comfy saddle on the old skool rig. Just don't ask me to take either of them off-road. Got me smiling when I thought of the advantages of going electric - no more 2 stroke to mix, riding in blissful silence free of fumes, able to enjoy the places I find myself in without creating a disturbance.
Seeing these got me thinking about what's happening with the SmartGrid-SmartCity initiative for Newcastle, which we discussed as part of an industry workshop during the Hunter EV Festival. They'll be using a fleet of 20 Electric Cars across Sydney, Central Coast and Newcastle to do some modelling of electricity demand on electricity grid to see if they can make some predictions about how that load and user behaviour might extrapolate at scale. Current market prices put a Mitsubishi iMiev at around $48,000 excluding OnRoadCosts, giving us a vehicle that has an effective range of 155km maximum.
Gee. Wow. Gosh. Oh My. It reminds me of one of the posts from a US-based Stealth electric bike owner that had participated in a group ride with 15 other standard bikes for up to 145 miles (230km). And had a blast, being able to chat along the way with the group whilst averaging about 25-32km/h. Not that you can do that in Australia, with our 25km/h power assist cut-out limit.
I wonder what sort of modelling went into thinking about the net impact of the iMievs on longer term health of its occupants, who'll remain sedentary. Who'll still be just as stuck in traffic congestion as their non-EV'd car based cousins. Who won't feel the pleasure of wind across their face as they cruise past lines of stuck traffic in their morning commute. Who'll be stuck behind glass, disconnected from their context, coccooned and sated.
I bet they won't be having as much fun as the guys in the video below, who are getting waaaayy more bang for their buck, on a bike that represents a very modest investment compared to an EV'd car. Remember people, an EV car is still a box on wheels that does little to fix congestion issues. They get stuck in traffic too. They also need to be parked, just like any other car. And there's no way you can use one for a quick ride on a local bush trail with all the grin factor and fun that's involved.
I also wonder why someone hasn't yet set up an EBike or Active Transport CRC in a city where obesity is a looming health issue, with some decent cycling infrastructure. Maybe it's because there's plenty of the former, too little of the latter. I'm sure they could do a lot with the $980,000(49k x 20) that's just been spent on Mitsubishi EV's. When I asked the question of attending Infrastructure Australia representatives, health and social benefits don't factor directly in their decision making for community infrastructure projects. Go figure.
It's time for change. If there is anyone wanting to partner on Active Transport research involving Ebike trials as part of that mix, I'm all ears and ready to help. Or perhaps the role they have to play in replacing dirtbikes as an environmentally friendly alternative. Either way, there's more modelling to be done than just presuming we're all buying into a transport future that's centered on car usage. Because that's a one way trip..