We had a good day out yesterday, a good ride, good company and even a ray of sunshine. The climb up Gatton Bottom to Reigate Hill impressed quite a few riders, so, as one of the 'Electric Hares', I thought I'd do a short piece showing how it works out with electric assistance.
Starting with the bike, I was riding a Boardman ADV 8.7E. It's a fairly modest machine; aluminium frame, SRAM Apex 1X and Schwalbe G-One Speed tyres. The defining element of the bike, as with all e-bikes, is the motor system. The difference between motor systems is much greater than the difference between bikes. I bought this one last summer to ride gravel trails and trackways, I've done a lot of them and it has worked very well. The Boardman has a Fazua motor system, which is middle-to-lower end of the power available for e-bikes, and it's just the thing for gravel riding, or, indeed for general road use.
The Fazua system fits in to the downtube of the bike. The black tube in the picture contains the motor and a battery, you remove it to charge the battery and you can even ride the bike without it, if you want. If you do this, a plastic tube covers the hole in the frame. A gearbox in the bottom bracket joins the motor to the pedals. This is a fancy piece of kit. It measures the power that the rider is producing, and provides matching power from the motor - I'll come back to this, as it's quite significant. It also contains an automatic clutch, so that the motor is completely disconnected from the pedals when you are not using it, allowing you to ride the bike without any drag.
Let's take a look at the power. The Fazua system allows the rider to choose from one of three power levels; Green, Blue and Red. You change between them by just pushing a button. The bike is delivered with the power levels preset, but I have changed mine quite a lot, as the standard settings envisage a rather younger, and stronger, rider. You change the settings using a laptop connected to the bike; if you're happy with your work it's a one-time job and you need never bother again.
Here's how you do it. For each power level, Green, Blue and Red, there are sliders to set the amount of rider power, the amount of motor power, and the rate at which the power is introduced. These days I can do about 200 watts, and I can't keep that up for long, so I have set my base power at 100 watts for Green and 150 Watts for Blue and Red. I can hold this power output for a long time, if I need to. For Green I have set the motor to go smoothly from nothing to 100 watts, so when I am riding at 100 watts the motor will give me 100 watts on top. Blue is 150 watts with 200 on top, Red is 150 watts with 250 on top.
Right, over to Gatton Bottom and let's see how this looks on the road.
Here's a power chart from yesterday's ride. The black box highlights the power output at the steepest point on the hill. As you will see, the gradient is 13.9%, which is fairly steep, I was doing 6.4 mph and the power was 356 watts. I was riding on the Blue preset, so 200 watts of this comes from the motor, and 156 watts from me. That's a reasonable amount of work, but not crippling.
Less powerful and more powerful motor systems are available, each has its advantages. With a less powerful system you do more work, a more powerful system gives you the choice of doing less work, or going faster up hill. UK regulations cap all e-bike motor assistance at 15.5 mph, so, above that, it's just you and the bike. Obviously, it's a bike, so you can go as fast as you like (or at least, as fast as you can), but there's no motor help over 15.5 mph.
Putting all of this in context, it's worth comparing these numbers with professional cyclists on big hills. Chris Froome, for example, can put out about 400 watts on a sustained basis, and I've no doubt he can do more, if put to it. If he had been riding up Gatton Bottom yesterday he would have beaten me, but not by a huge amount. I'm very happy with this. I'm an old man, not all that fit, but I can still get the pleasure of the road, and the pleasure of the hills, with a little help from my electric friend.
Mark
6 comments:
Interesting Mark, thank you for posting.
Thanks Mark - for a succinct explanation of the technology. What I don't understand is the pedalling dynamics - i.e. the relationship between gears, cadence and assisted power. Typically, on Wednesday's climb, do you keep the same cadence and same gear, increasing assisted power; increase cadence and change down with less assisted power; or a combination of both?
The technology is pretty sophisticated, but it's very straightforward to use. You simply pedal at the cadence and in the gear that suits you, and the motor follows along according to the setting you have chosen. It provides power in proportion to the effort you make.
On Wednesday, when I spoke to you at the bottom of the hill, I switched the motor to Blue, as I knew there was a big hill coming. I then just rode away, setting the gear to suit myself. The gear would certainly have been higher than it would have been without the motor, as I was getting up to 200 watts additional power, but it's not noticeable to the rider.
If I had chosen Green, then I would have gone up the hill in exactly the same way, but a little slower and in a lower gear as the motor would only have provided 100 watts. Equally, I could have turned the motor off and just ridden up in the normal way. The bike's not particularly heavy and there's no drag from the system, so it's perfectly possible if you want to.
Q.E.D.!
I found that to be massively interesting. The only question for me is how much more will I observe myself slowing down and deteriorating before taking the big step.
I finally gave in to buying an electric bike when I was regularly overtaken by walkers on the hills in Richmond Park. 40 years of playing squash every day had taken its toll of my knees and back. I discovered on my indoor trainer I could only generate about 75 watts and was kept awake by knee pain most nights after a ride. My weekly mileage was going down steadily and I was not enjoying riding anymore.
I bought an E-mountain bike to allow me to tackle anything. What a revelation all the pleasure of riding with none of the pain! To get the best out of the motor you need to pedal fast : cadence over 80 . So I am getting plenty of low stress exercise and can go out with my pals again and sleep peacefully every night.
My weekly mileage is 150 miles and climbing every month. My only problem is I have not used any of my regular bikes since and although my legs are far stronger I still cannot generate more power without the pain.
I would strongly recommend anyone to try an E-bike : you will be amazed; and to buy the most powerful motor you can afford to future proof your purchase as you get older and weaker. It will keep you riding and protect your joints from the ravages of arthritis.
Alan L
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