How Important Is Power On An E-Bike? | EMBN Investigates

How Important Is Power On An E-Bike? | EMBN Investigates


– Power, is it important? Yeah it probably is if you’re doing flat out fire road sprint tests. But if you’re in the mountains,
I think you’ll probably find that power is nothing without control. – Now before we get into it let’s find out exactly what power, watts and torque is. Power is the total output
that a motor can put out and is a measure of the
rate of work the motor can do over a period of time. It is measured in watts
and can be explained by this equation, power
equals force times velocity. So in general, the more force
a motor can put out over a shorter period of time
the more power it’ll have. And of course the crazier
climbs you’ll be able to do on your e-mountain bike. Now watts are a measure of the
rate that power is generated or consumed over time. One watt is the equivalent
of one joule per second and the the more watts a motor can produce the more power it will have. Now torque is the
twisting force that tends to cause rotation and is
measured in newton meters. The higher the torque figure, the more twisting force
a motor can put out. Torque is therefore a better
indicator of how quickly your e-bike will accelerate
and power itself. So very simple, but the
key part here to remember is that maximum watts an
E-mountain bike can produce is closely linked to the speed
you are spinning those cranks Now most of the time power
is gonna be of most use in a climbing environment,
rather than a downhill one, so that’s what we’re gonna focus on today. But first of all, let’s have a look at the ways of measuring power. So what are the watt numbers
on electric mountain bikes? Well this pedal assist
electric bike such as the one I’m riding now, are actually
restricted to 250 watts average But it does actually
vary from brand to brand in terms of the maximum output. For example a Shimano
E7000 motor can kick out over 400 watts max, whereas
a Specialized Brose motor, about 560, and a Rocky Mountain
over 700 watts maximum. I think in many ways
you can actually compare an e-mountain bike to athletes,
different types of athletes sprinters or long distance runners. For example my colleague Dan Lloyd on GCN. No angel when it comes to lifestyle, but he can sustain 300
watts over a one hour climb. Compare that to say a top
level Tour de France racer such as Richie Porte who can sustain about 400 or 500 watts
over the same climb. And then you got the sprinters
such as Andre Griepel who can do 1900 watts over a short period. I think what we’re saying here
is that e-bikes don’t produce any more power than what a
top level athlete can produce. And that when you’re
comparing e-bikes to athletes, e-bikes are probably more
long distance runners than sprinters. So I guess the next question
is, does rider power matter? Well yes it does but not
quite as much as technique. And what about motor power,
how does that help you when you come to a classic
e-mountain bike situation such as this, is more power really better? So what are the factors
effecting your ability to control your e-mountain bike then? Well first of all software,
now some motors are open to manipulation such as Brose and Shimano whereby you can control the way the power is delivered to the back tire. Then of course, such as
things as componentry, tires and gearing. Geometry has a big impact in your ability to control your bike, because chainstays, short chainstays are
more difficult to control than longer chainstays when
it comes to hill climbing. And then of course let’s not forget two important factors such as mode. How much assistance are you
gonna be using on your e-bike. And finally the ground conditions. (chill electronic music) So we’re here in the
amazing Lake District. And I wanna show some examples where power counts for
little without control. My first example is in this
pretty snotty bridle way climb. And what’s gonna be of importance here is such things as timing,
it’s pointless having power if you can’t use the timing
right, pushing on the pedals in the right places to get up
over these little rock steps. There’s probably about 200 of
them on this particular climb. So you’re out in the
mountains doing a mega loop and it’s quite possible
you will come across a section such as this. And you’ll never have
ridden it before maybe, but it’s really important that you hit it correctly first time. And of course mode is
gonna be very important in how you tackle this,
’cause it’s very easy to think, yeah, stick it in boost mode and it’ll power me through,
but sometimes boost mode will actually push you
forwards a little bit too far and rush you through the section. So that means you’ve got
little control over your bike. So I’ve selected trail
mode on my 70 newton meter Canyon Spectral:ON with
a Shimano E8000 motor. I’m gonna attempt this
technical rock section for the first time. Now remember, if you get
it wrong, you’ll probably be pushing your 20 kilo
plus e-bike up that section. So it’s really critical to get it right. I’m feeling a bit nervous, but here we go. Think you just gotta take it easy, really really take it easy. I think your confidence just builds. I guess then of course, things can get ridiculously technical. And in such situation the control variable is actually your fitness,
not the power of the bike. Beasting yourself in the Lake District. Now again I’m on the Levo in trail mode. Feeling a little bit nervous. (pants) Wow. Can’t believe I’ve actually done that. Now don’t you get the idea that I’m saying more power is (bleep), what I’m saying is more power is good, but
you still need to be able to deliver the power and control it. Sometimes it’s actually better
to have softer lower power when it comes to technical
sections like this. Clearly if this track was
smooth and flat, then more watts and more power is gonna
get to the top quicker. However, when things get technical
such as places like this, It’s not just about power,
it’s actually about technique. Choosing the right line,
keeping your weight on the rear tire enough. Power’s not gonna get you
up this hill any easier than one with a little bit less. Now as you saw on the
previous run on the Levo, I was trying to race up this
super technical rock climb. I was trying to box clever,
because when you have climbs like this, you might have to sustain a run of about 400 meters, 800 meters, you simply won’t do that
by racing up the hill. Another classic situation,
we’ve spent the last 15 minutes peddling up a rock bed and
now we’re out of the bed and onto a really slippy muddy bank climb. So here, the factors effecting power are gonna be such things
as componentry and cadence. Now on the Canyon Spectral,
we’ve got a two point eight, Maxxis Minion DHR II in the back. And that’s gonna compare to the Shorty which is more of a mud tire on the Levo. Let’s see how they get on. So again, cadence is really important. Easy. Right let’s see what happens,
if we back off the cadence on this bike and make it more ragged. So I’m going slow and
then trying to go fast. So again, that’s not about the power. It’s about the way you spin the pedals on your e-mountain bike. Now both these tires aren’t
particularly soft compound and the Shorty’s more of mud tire, than one you’d actually use on rocks. So it actually hasn’t
excelled in the rock sections we’ve been riding so far,
but on this muddy bank, I expect it to have a slight
advantage over the Minion. Yeah it’s far easier to
control that grippy mud tire. I’m guessing I can probably
be a little less subtle with my cadence with this mud tire. I could push it down
hard and it’ll dig in. Which is what will not
happen on the Minion. And finally a crazy steep rock section like the ones we’ve been doing earlier. Now what I wanna focus on here, is the effect of geometry on power. And in particular chainstays, now short chainstays and long chainstays. Short chainstays start
about 420 millimeters, where long chainstays, such as the ones on the Mondraker Level
go up to 490 millimeters. And what that means,
there’s gonna be a different weight bias depending
on the chainstay length. Short ones you’re gonna be over the back, long chainstays you’re
gonna be over the front. So you need to be really careful in how you position your body, when you’re going up big climbs like this, it really will effect
how that bike climbs. There’s no point having all that power, if you can’t get your body
in the right position. So what do we mean then
when we talk control. Well very often you’ll be riding sections like this ahead of me blind on an e-bike. So it’s all about interpreting the terrain as you get up there. Now this is my first ride up this climb, again I’m just trying to take it easy and pick my way up there. Okay, same run again, now
I’m on the Specialized bike, whereas previously I was on
the Shimano E8000 system. Again it’s no easier, it’s
just about picking your lines. Power then, yes it probably
will win you over in a car park or on a fire road sprint test. However, don’t forget some of the other more important factors when it
comes to riding your e-bike, such things as agility,
stability, handling and fun. And then about power, more power, well that’s gonna equal less range. And then that final important factor, the feeling of the motor,
does it feel natural? Or does it simply feel overpowering. So there you go, Boredale e-bike heaven. Don’t forget to click on the
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technical videos such as this. If you want to see more
check out the video I did on e-bike motor fundamentals down by here. In the meantime, don’t forget
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