Cadence

[Andy.M]

Been emtb'ing for over 3 years now and never even thought about cadence until today!
Seem to remember a youtube video saying cadence should be between 80-100 so I had a quick 12 mile road ride today with cadence on the display rather than speed.
Ok keeping 80 wasn't too bad but hitting 100 and keeping it there was hard to say the least as I was well past the motor cut out point.
After 3/4 hour nonstop riding keeping the cadence around 80 I arrived home breathing quite deeply.
So you guys who are into your fitness regimes is cadence a thing you do and what rate do you like to achieve?

 

[Zimmerframe]

Bosch Gen 2 ?

The motors all vary quite a bit.

One big difference is that whilst you're knackered, the motor will have been working efficiently so you should find your range increases considerably. Also, the motor will be cooler as it's working efficiently, so potentially more reliable over time.

If you're not used to a higher cadence - at first, like any "fitness" exercise, it will feel unusual and difficult. Basically just stick at it , pick a cadence range and distance and just build up. Take some breaks with a lower cadence for 30 seconds or so once in a while until your body adjusts.

 

[Andy.M]

Not bosch a Shimano E8000. Did not think about different motors.

Bearing in mind I'm the wrong side of sixty, I'm not after a full body workout every ride but certainly recognise I can get my fitness levels up by using cadence

 

[Mikerb]

Cadence on an emtb is more about efficiency. Every motor has an optimum cadence which for most is between 50 and 70 with some motors having a wider range than others, and obviously good use of the gears enables you to maintain a cadence in that range over varied terrain. The motor is working well within its maximum torque band and at the same time you are putting less strain on the drivetrain.

Spinning at 80 to 100 is going beyond the optimum cadence range on most motors and is probably only possible for any duration in any case on tarmac.......but an EMTB is not designed for that......too much weight, too slack, too much rolling resistance etc.

Where you might use that sort of cadence is on a steep offroad climb in a very low gear in turbo.

 

[Zimmerframe]

Cadence on an emtb is more about efficiency. Every motor has an optimum cadence which for most is between 50 and 70 with some motors having a wider range than others, and obviously good use of the gears enables you to maintain a cadence in that range over varied terrain. The motor is working well within its maximum torque band and at the same time you are putting less strain on the drivetrain.

Spinning at 80 to 100 is going beyond the optimum cadence range on most motors and is probably only possible for any duration in any case on tarmac.......but an EMTB is not designed for that......too much weight, too slack, too much rolling resistance etc.

Where you might use that sort of cadence is on a steep offroad climb in a very low gear in turbo.

You've done it now .. it's cadence wars !

The e8000's a weird little beast. Even now I have a few climbs where it's faster than my brose. I found for "power" your subconscious seemed to map with the shimano motor easier than other motors to work out what cadence worked best in what situations - which with the shimano is often lower than the optimum efficiency cadence. (if you're being lazy).

For efficiency, higher cadence will be more efficient though.

An example (from 1982 - well, it feels like it) , but take it with a 50kg sack of salt ..

 

[steve_sordy]

Let me check something here.

Cadence is how fast I pedal. I tend to pedal with a certain leg force that I am comfortable with to protect my knees. If I 'm going too slow for my cadence, I change to a harder gear so I go faster. I'm still using the same leg force. When I come to a hill and start to slow down, my leg force increases, so I change to an easier gear to maintain my preferred cadence. It is only when it gets really steep when preferred cadence and leg force goes out the window and I just do what has to be done to get up the hill / over the peak / whatever.

When I read about higher cadences being "better" for battery life, I take from that they mean pedal faster for the same ground speed. This will reduce my leg force and reduce the power I take from the battery. That may be better for my knees, but it sure doesn't feel like it.

What I don't do is to just increase my cadence and go faster across the ground, that way lies knackered knees for me and a shorter life battery.

 

[Pdoz]

Anyone still mtb riding when over 60 has the right to ignore some whipper snapper on youtube.

 

[steve_sordy]

You've done it now .. it's cadence wars !

The e8000's a weird little beast. Even now I have a few climbs where it's faster than my brose. I found for "power" your subconscious seemed to map with the shimano motor easier than other motors to work out what cadence worked best in what situations - which with the shimano is often lower than the optimum efficiency cadence. (if you're being lazy).

For efficiency, higher cadence will be more efficient though.

An example (from 1982 - well, it feels like it) , but take it with a 50kg sack of salt ..

View attachment 52001

The Shimano e8000 has a wide and relatively flat power curve doesn't it? 450-480 and back again over a cadence of 70 to just over 100.

 

[flash]

You've done it now .. it's cadence wars !

The e8000's a weird little beast. Even now I have a few climbs where it's faster than my brose. I found for "power" your subconscious seemed to map with the shimano motor easier than other motors to work out what cadence worked best in what situations - which with the shimano is often lower than the optimum efficiency cadence. (if you're being lazy).

For efficiency, higher cadence will be more efficient though.

An example (from 1982 - well, it feels like it) , but take it with a 50kg sack of salt ..

View attachment 52001

When climbing wouldn't torque versus cadence matter as much as power?

Gordon

 

[Zimmerframe]

When climbing wouldn't torque versus cadence matter as much as power?

Gordon

Logically, yes .. that's what I mean about the Shimano motor, for me anyway, being a bit of an anomaly.

 

[Mikerb]

Yes it was torque rather than power II was referring to. The attached is probably a little out of date but was originally posted up by Rob. As you can see the max torque for most motors drops off radically after a cadence of c 70. The torque curves being fairly typical for electric motors. An even torque right from startup ( which is why electric cars have crazy acceleration figures...up to a point) but then drop off a cliff beyond a certain cadence/rpm.

 

[Andy.M]

Wow, interesting subject!
So from the first diagram (power/cadence) my Shimano is delivering good power at higher cadence which may account for why I felt I wanted to just keep pumping away (on a road).
My older bike (still got) has a Yamaha motor. Looking at the diagram it could explain why I never felt the urge to pedal higher cadences as there is no power in that range.

The second diagram (torque/cadence) Is that showing that for climbing off road, a lower cadence is better than going ten to the dozen with the legs?

Please excuse me if I'm totally wrong as this science is all new to me.

 

[Zimmerframe]

You have to be very careful with the graphs as they're all very subjective and generally not very accurate. There's also "motor" torque and "Wheel Torque".

Mate Explains it far better than I would from the links in this thread :

Should e bikes have gearboxes?

Here's an overview on gearboxes: https://www.singletracks.com/mtb-gear/internal-gearbox-advantages-drawbacks-and-future-possibilities-for-apocalypse-ready-mountain-bikes/ The primary reason gearboxes haven't seen widespread use on regular bikes is because of the added weight and the efficiency...

www.emtbforums.com

 

[R120]

With EMTB's there's one relatively obvious impact of cadence which doesn't need a graph to explain, or be motor specific, which is that if you are grinding up climbs with a low cadence you are using more motor support, and thus more battery, whereas if you are spinning up then the opposite is true.

 

[steve_sordy]

No matter what power mode you are in, the assistance from the motor is proportional to the torque provided by you, unless it is capped by the software. Torque is pressure on the pedal multiplied by the crank length. So if you keep a low leg pressure then you will be taking less assistance from the motor and hence take less energy from the battery. But you can't creep about like that all the time as it's no fun! However, going slowly up hills in Eco instead of hurtling up at warp speed in Boost is a sure fire way to maximise your range.

As a reminder: power is proportional to torque x cadence.
If you choose the correct units, power equals torque x cadence.

 

[Andy.M]

My heads exploded now, I'll just ride it!

 

[B1rdie]

I strugle to maintain 80 rpm with my bike but with the ebike its easy to pedal to 90 or more. On flatlands I can maintain 100 rpm easily, with 110-120 it gets close to the 32 km/h limit of my shimano 8000.

 

[ggx]

I started to pay more atention to cadence and is benefits wen I started to occasionally ride road bikes some years ago. So, gradually I´ve started to push it and riding in acording gearing. Now I ride more confortably in higher cadences than previously.
In consequence transition to e-bike was smoth .

 

[Mikerb]

It is relatively easy to measure the torque ...ie the capacity of the motor to do work. You can measure that at the rear wheel in much the same way as a dyno does for a car, or you measure that at the motor planet gear which would eliminate the drivetrain losses. Power is torque x speed...( speed being the rotation of the electrical motor). Both of those will be measured for each of our emtb motors...AT THE MOTOR.

But now this is the point where there is a complication. Our bikes are not directly driven by an electrical motor. The motor merely provides pedal assist.

On our bikes, software controls the way in which that power is delivered to the pedals. One controlling factor is the measurement of torque the rider applies to the cranks and for most Ebikes...but not all...also a measurement of cadence. The software can regulate modes to enable either of those 2 factors to have the more or less dominant impact on power delivery. On some EMTBS the user can also regulate those factors via end user software like Specialized's Mission Control. For example the "shuttle" setting on Mission Control, places more bias on cadence. The result is that you get max pedal assist by spinning fast in that mode.

For me, forgetting the science, part of the experience of an EMTB is getting a feel for the characteristics of the motor. It is relatively easy to find how to get the maximum torque because it enables the maintenance of a good speed with least rider effort. Similarly, in time you can determine how best to tackle a technical climb using a gear/mode/cadence combination that ensures good traction plus ample power.

 

[Zimmerframe]

You also need to keep in mind that the software is not "perfect" .

So as the Wizard was saying, pedal slower, less power - but it's not as simple, you might be pedalling slower but the torque sensor might detect that you're trying to pedal hard - so as a petrol engine would with an accelerator - it tries to accommodate.

BUT .. because it doesn't know what gear you're in or many other factors, it simplifies it and just throws all available power at the motor in an attempt to accelerate.

Because the motor speed is low - and trying to increase - maybe unsuccessfully - the motor is incredibly inefficient at that speed, so the majority of the electrical power being used is converted to heat, which will waste your battery and enormously increase wear on the motor.

This will probably improve over time with additional sensors (to go wrong) and much better algorithms - but it's still very much in it's infancy. Like Steve, who looks more mature than he is .

There's obviously a range for how this affects things. With the Spesh motor you can run an app and find out the power etc you were using at a cadence and so on. And see that at 60 - you're just burning power with no performance benefit. Most people over a ride won't notice it because that moment won't be the same for the whole ride. It's just a blip of inefficiency.

Have you considered a Kayak ?

 

[Gary]

With EMTB's there's one relatively obvious impact of cadence which doesn't need a graph to explain, or be motor specific, which is that if you are grinding up climbs with a low cadence you are using more motor support, and thus more battery, whereas if you are spinning up then the opposite is true.

That's not necessarily true.
the speed you climb at and assistance mode used makes most difference.
Power = load x velocity (torque X cadence)
Spinning in a low gear at a fairly high cadence but at normal bike climbing speed creates a fairly low torque and thus the motor doesn't add a whole load of assistance
Grinding at a low cadence in a higher gear means your torque sensor reads higher input and dependent on mode/motor it may well try to match your effort.
Of course each motor and mode have their own personal sweetspots for assiatance/efficiency.

Torque = force x radius
So... using that power equation it stands to reason shorter cranks can actually be less efficient too.

Cadence is very personal. One rider may struggle to even reach 100rpm nevermind hold it while another may comfortably sit at 100rpm and higher all day long and reach a peak cadences of 200rpm+. Thing is Improving your ability at higher cadence can be trained very easily as doing so is relatively low load exercise. Simply practice spinning at higher cadences (in low gears) regularly and your ability to spin faster will improve fairly quickly.

Saying mtb doesn't require faster cadences is silly. of couses it does. mtb is full of accelerations and decelerations. ie. short sprints. So being able to spin a high cadence and also being comfortable within a wide cadence range is pretty important.

 

[Zimmerframe]

Also... using that power equation it stands to reason shorter cranks can actually be less efficient too.

Rubbish ... Each time I don't hit a rock, I save energy !

Grinding at a low cadence in a higher gear means your torque sensor reads higher input and dependent on mode/motor may well try to match your effort.

This is where the Shimano ~(e8000) has a sweet spot where you can actually balance "lazy" with "fast" .. probably not good for the motor or battery, but good for the self esteem ..

Grinding at a low cadence in a higher gear means your torque sensor reads higher input and dependent on mode/motor may well try to match your effort.

I've heard this works on e-bikes too.

 

[Mikerb]

So as the Wizard was saying, pedal slower, less power - but it's not as simple, you might be pedalling slower but the torque sensor might detect that you're trying to pedal hard - so as a petrol engine would with an accelerator - it tries to accommodate.

BUT .. because it doesn't know what gear you're in or many other factors, it simplifies it and just throws all available power at the motor in an attempt to accelerate.

Where both a torque and cadence sensor exist ( and a speed sensor) the software algorithm is designed to optimise performance using all 3 inputs. This is precisely where the amount of development that went into designing that software determines just how natural the riding experience becomes plus the amount of current drawn in each of those circumstances.

Power = load x velocity (torque X cadence)

That is rider output power, not motor output. Motor output power is torque x Motor rotation speed.

 

[Gary]

Yes Mikerb If you re-read in context I was talking about rider output.

 

[Mikerb]

Yes Mikerb If you re-read in context I was talking about rider output.

ok but you go on to compare high cadence low ( bike) speed ......which you said results in low torque assistance from the motor, to higher bike speed and lower cadence/bigger rider torque, resulting in greater motor torque assistance.

My point was that the software computes 3 values in an algorithm. Bike speed, Cadence, Rider torque input. So what you say is not necessarily true depending on how the software developer set the algorithm for that scenario. Of course that software is kept secret for obvious IPR reasons. On my Levo, it invariable feels like cadence is given a higher percentage input to that algorithm when in turbo mode.

Certainly on my Brose powered Levo, with the mission control pedal assist and max power settings I have set, the optimum way to climb a steep technical ascent is in turbo ( pedal assist and max both at 100%/ acceleration at zero/ shuttle off) , a high cadence and c 9th gear ( 11 speed).

 

[flash]

All I know is I have to spin more on my EP8 motor than I did on my e8000. I'll get used to it. It's more road like in cadence. But for now I feel like a Hamster....

Gordon

 

[Gary]

No. mike that's not what I said.
Please take the time to re-read what I actually said.

far too many folk here have misquoted me and made up stuff I haven't said this week for me to be bothered going over anything i've said again

once you've understood what I actually said. you'll realise I was also saying

that the software computes 3 values in an algorithm

 

[Zimmerframe]

Yes Mikerb if you re-read in context and don't quote out of context and actually take it all in .. and then also watch the video I linked to - which I think explains it far better than I would in 5000 monotonous words.

Where both a torque and cadence sensor exist ( and a speed sensor) the software algorithm is designed to optimise performance using all 3 inputs. This is precisely where the amount of development that went into designing that software determines just how natural the riding experience becomes plus the amount of current drawn in each of those circumstances.

Because the motor speed is low - and trying to increase - maybe unsuccessfully - the motor is incredibly inefficient at that speed, so the majority of the electrical power being used is converted to heat, which will waste your battery and enormously increase wear on the motor.

This will probably improve over time with additional sensors (to go wrong) and much better algorithms - but it's still very much in it's infancy. Like Steve, who looks more mature than he is .

Trust me .. I'm not trying to be an arse ... I don't have to try .. You're just hugely simplifying things and massively giving more credence to the "algorithm's" in the motors than is even remotely relevant at this stage. Go be boring and have a look at the software in a motor update - most of it's reactive hardware with only a finite degree of software at the core level.

You're also making the huge mistake that everyone makes that electrical motors provide 100% torque at 0rpm and then assume a corresponding 100% efficiency in how that's used.

Anyway, if everyone's doing head in the sand, I'm out .. I've flames to watch which are far more interesting.

 

[Gary]

All I know is I have to spin more on my EP8 motor than I did on my e8000. I'll get used to it. It's more road like in cadence. But for now I feel like a Hamster....

You don't actually "have to" spin at any particular speed. All mid drive motors operate within a range of cadences.
all of them drop off their assiatance output considerably at genuinely high cadences.

 

[Gary]

I'm tapping out too