How much power am I contributing?

[Chris.mitu]

Hi
I was trying to figure out how much power and calories are going into my ride using my Boardman Hybrid with the Oxydrive 13a kit but my lack of understanding of how these kits work is defeating me.

I looked t the Woosh bikes predictor and it estimated that I need 470WH for my return journey. If it takes me two hours for a return journey am I looking at 940W? Commute is over 33miles.

http://www.wooshbikes.co.uk/clearway.php?

The battery is advertised as I=13A. When I start my ride a fully charged battery shows V=41 and when I return home V=36.5.

Using P =I x V tells me that the battery has 533W at the beginning of my commute and 474.5W at the end of the day. This means that I only used 58.5W.

Either the V reading from the computer is wrong or my asumption of the current being constant at 13A is wrong.

How would one work out how much legwork is going into a commute?

Thank you

 

[RobF]

One of the problems - if you can call it that - with ebikes is they don't do a lot to get you fit.

Or if you are already cycling fit, you will lose some of that fitness.

Pedal sensor bikes such as yours are even worse in that respect.

At least with a torque sensor bike - such as a Bosch equipped one - you have to pedal harder to get more out of the motor.

This can be frustrating on steep hills, because as you weaken and put in less effort, the motor also cuts back - just when you want it to do the opposite.

I reckon even with a Bosch bike, which does encourage you to pedal harder, you still need to do three or four times the mileage of a push bike to get the same fitness benefit.

In other words, 30 or 40 miles on my Rose is about the same as 10 or 15 on my Cannondale mountain bike.

Riding in lowest eco mode helps gain fitness, but the only way I've managed to make much progress is by getting out and doing the miles on the Cannondale.

 

[Chris.mitu]

Very fair point. I am not deluding myself that it is making me fitter I do however feel that my legs have had a workout when I walk around after a ride.

For example my motor cuts out at 16mph however I generally cruise at 17mph + (not on hills) so I am assuming that my legs are keeping the momentum going when cruising above 16mph.

I am wondering how I can estimate what that effort is?

 

[trex]

I looked t the Woosh bikes predictor and it estimated that I need 470WH for my return journey.

You need 470WH for 33 hilly miles. The woosh Predictor is slightly pessimistic, you are young and strong, you'll probably need less than 350WH for 33 miles.

 

[selrahc1992]

Very fair point. I am not deluding myself that it is making me fitter I do however feel that my legs have had a workout when I walk around after a ride.

For example my motor cuts out at 16mph however I generally cruise at 17mph + (not on hills) so I am assuming that my legs are keeping the momentum going when cruising above 16mph.

I am wondering how I can estimate what that effort is?

I have the same experience,my 13ah oxydrive kit is derestricted and tops out around 22 to 24 mph,I cycle home 13 miles today constantly 24 to 25 mph on a racer with it,the LCD scd shows the system uses almost no energy 70% of the time,the Max energy it gives the other 30% against hills makes it a non painful journey, I arrived home literally soaked

 

[Deleted member 4366]

There's a few mistakes in what you wrote. It's not a 13A battery, it's a 13Ah one, which means approximately 470 Wh in it. You can extimate how much of it you used from the voltage. From fully charged to 36.5v is about 60% of the battery, so you used about 280wh.

You now need to use an app on your phone, like "Sports Tracker" that will estimate the total calories for your exact journey. To convert Calories to Wh, you multiply by 1.163. You then take 280Wh from that number and you're left with your contribution, approximately.


280wh for 2 hours means your motor was averaging about 140w. You need about 250w to reach 15 mph on a normal upright bike, so that would mean that you contributed an average of around 110w.

These figures are all estimates. Wind an hills can throw them out a bit.

280wh for 33 miles is 8.5 wh/m, which is not a bad figure. With my hilly rides over about 30 miles, I've been in that range a few times, but only with an average speed of about 12mph on my MTB. When I was testing our Gadget show bike, it was pretty clear that it was much more efficient than my MTB. I'm pretty sure that it would match your figure if I put in a bit of effort. Shortly, I will be doing some tests to see how much difference an efficient bike makes.

 

[eHomer]

One of the problems - if you can call it that - with ebikes is they don't do a lot to get you fit.

Or if you are already cycling fit, you will lose some of that fitness.

Pedal sensor bikes such as yours are even worse in that respect........

That statement has surprised me, albeit that it was qualified with the word "some".

I have no hard technical facts or links to counter it, but my overall impression of five years extensive eBiking does appear to have made me fitter, and I have lost weight, (even though I'm still about a foot short for my weight ).

My ebikes have enabled me to cycle around 25 miles or so about three times a week, along peaceful lanes in wonderfully flat Norfolk.

I almost invariably use assist level one with 250 to 350 watt motors, to maximise range and (as I thought), still give me exercise.

The 25 mile rides are much more interesting and enjoyable than the 5 mile rides that are my maximum comfortable range on my unassisted bikes.

I was always under the impression that was one of the big attractions for eBikes for non athletic types like me, enabling us to cover much longer distances, yet still get good healthy exercise ?

 

[RobF]

That statement has surprised me, albeit that it was qualified with the word "some".

I have no hard technical facts or links to counter it, but my overall impression of five years extensive eBiking does appear to have made me fitter, and I have lost weight, (even though I'm still about a foot short for my weight ).

My ebikes have enabled me to cycle around 25 miles or so about three times a week, along peaceful lanes in wonderfully flat Norfolk.

I almost invariably use assist level one with 250 to 350 watt motors, to maximise range and (as I thought), still give me exercise.

The 25 mile rides are much more interesting and enjoyable than the 5 mile rides that are my maximum comfortable range on my unassisted bikes.

I was always under the impression that was one of the big attractions for eBikes for non athletic types like me, enabling us to cover much longer distances, yet still get good healthy exercise ?

'Some' is the key word.

A fit cyclist will inevitably lose some edge off his fitness on an ebike.

It's different for the rest of us.

I am like you in that ebiking made me a little bit fitter, albeit starting from a very low base.

Also like you, it's the distance I like so an ebike gives me a much bigger range.

The amount of exercise depends on your bike and particularly how much power you ask from the motor.

If the bike is set so the rider could, in truth, turn the pedals with his little finger, then he's not getting much exercise.

It depends on what you want to achieve, some gentle pedalling while getting out in the countryside is great and it's a shame more people don't do it.

I didn't lose weight when I started ebiking, you did, so we are all different.

Riding my Cannondale and eco setting on the ebike has contributed to some weight loss, but I think shifting the pounds is 90 per cent about diet.

 

[Croxden]

I lost a stone after the Delite came because my mileage went up because it being so good to ride, I went further.

In another thread, RobF said I ride to hard to get the economy that some folk are able to get. You can't have both ways.

To remain healthy you need exercise, just sitting and not eating might not get you fat, but is it good for you?

 

[flecc]

That statement has surprised me, albeit that it was qualified with the word "some".

I have no hard technical facts or links to counter it, but my overall impression of five years extensive eBiking does appear to have made me fitter, and I have lost weight, (even though I'm still about a foot short for my weight ).

It is indeed all about relative fitness. Despite my very long term interest in power assisted cycling techhnology, I was always an unpowered cyclist and still very fit at 67. That was when I first bought an e-bike to help with heavy goods trailer pulling in my hilly area.

That was the start of it spoiling my fitness and I was never able to recover it, a year later giving up unpowered as being too much on the steeper hills. Hills that I used to revel in climbing at speed were suddenly exhausting me and removing all the fun of cycling element.

But there's no doubt after all the evidence in this forum that e-bikes can dramatically improve the fitness of an unfit person, so it's all about the start point.
.

 

[selrahc1992]

I lost a stone after the Delite came because my mileage went up because it being so good to ride, I went further.

In another thread, RobF said I ride to hard to get the economy that some folk are able to get. You can't have both ways.

To remain healthy you need exercise, just sitting and not eating might not get you fat, but is it good for you?

In my life that is very true: the choice isn't between doing a 23 mile commute on a pedelec or a normal bicycle - its between a pedelecs and a car. A normal bicycle would always feel too difficult/sweaty/awful in winter to do it with. a pedelecs has to be healthier than sitting in a car.
a tangent - but on a treadmill last night I was thinking about this energy calculation: whether one uses a step machine or a treadmill at a heart rate of 160 feels very different (the treadmill like a systematic form of excruciating torture after forty minutes or so, the stepper like a brisk walk up stairs) - but both must burn similar energy (given same heart rate). Clearly things aren't always what they seem.

 

[eHomer]

Yes, I can appreciate the logic in the replies to my post querying the level of exercise between eBikes and conventional bikes.

I'm definitely in the "low base" category from the point of view of exercise.

I go with the consensus that ebiking has artificially enabled me to regularly achieve fit cyclist distances and speed, rather than having to just pootle around the block at fast walking speeds.

Fifty years ago, I used to ride a trade bike for an off-license, and rode many miles a day with crates of Schweppes and such in the front carrier. Single speed, rod brakes, and as heavy as hell, yet I had the stamina to stand on the pedals to get up the hills.

Bloody cars... if only I could have skipped that phase of growing up.

 

[flecc]

Fifty years ago, I used to ride a trade bike for an off-license, and rode many miles a day with crates of Schweppes and such in the front carrier. Single speed, rod brakes, and as heavy as hell, yet I had the stamina to stand on the pedals to get up the hills.

Me too from 11 years old in even bigger doses. Five and a half days of morning and evening paper rounds with the small front wheel and low platform version of those heavy trade bikes.

Saturday for the butchers delivering weekend joints and collecting the cash, using the larger wheel and front basket version of those bikes.

School filled the weekdays between the paper rounds, but I did get Sundays off!

Had to give up the butchers job at 13 years old when the blasted school extended the school week to include Saturday mornings, 9am to 1pm.
.

 

[Deleted member 4366]

I did a little test today. I went out on my roadbike and did just over 6 hilly moles in half an hour recorded by Sports Tracker. It told me that my average speed was 12.9 mph (I lost a few minutes to hook the chain back on twice) and that I burnt 326 calories, which equates to 379wh, which means an average power of 180w. It seems a little high for no electric motor.

Sports tracker doesn't have any settings for the type of bike, but it does for weight, which had been set about 20% low.

 

[bgt]

Before I had the ebike I use to cycle 15-25km a week. Now I do 150-200km a week with pleasure/fun. Even with the home made ebike I have now(PAS in "current" mode) I gained a lot of fitness. I left the trade mill of the fitness school and swapped it for the ebike and am very pleased with it. I hardly use the car anymore so thats a big plus.

 

[SpezElec]

nice reading,chaps..

if you want to loose weight,use low carb high fat diet and train your body to use ketones,ride on empty stomach

if you want to be fit,use you ebikes,road bikes,MTB,cyclocross as often as you can,ride hard at times

 

[One_Box]

Hi
I was trying to figure out how much power and calories are going into my ride using my Boardman Hybrid with the Oxydrive 13a kit but my lack of understanding of how these kits work is defeating me.

I looked t the Woosh bikes predictor and it estimated that I need 470WH for my return journey. If it takes me two hours for a return journey am I looking at 940W? Commute is over 33miles.

http://www.wooshbikes.co.uk/clearway.php?

The battery is advertised as I=13A. When I start my ride a fully charged battery shows V=41 and when I return home V=36.5.

Using P =I x V tells me that the battery has 533W at the beginning of my commute and 474.5W at the end of the day. This means that I only used 58.5W.

Either the V reading from the computer is wrong or my asumption of the current being constant at 13A is wrong.

How would one work out how much legwork is going into a commute?

Thank you

At the best you will only get an approximation.
When I complete a ride on my road bike the data is recorded with my Garmin satnav cycle computer. It is then downloaded into Garmin Express and Ride with GPS. Even though both programs know my personal data they produce different figures for calories used for the ride no doubt because they use different algorithms. Which is correct? I have no idea so I average the two.

If you now do the same ride on an E-bike you introduce another potential source of error ie the contribution the electrics have made to your ride. That is why I never record calories when on my Kalkoff or Parabike conversion.

 

[Deleted member 4366]

You can get a rough approximation by using an app on your phone, like Sports Tracker, which tells you how many Calories you burnt during the ride. Multiply that by 1.162 to get Watt-hours. Then you need to divide it by about 4 because your body is not very efficient at converting burnt calories into output energy. For the same journey, subtract the number of watt-hours on your watmeter times 1.67 because your motor will average about 60% eficiency from your previous total, and that's how much you contributed.

Example: you go on a 27 mile ride. Sports Tracker says you burnt 1800 Calories, which is 2092Wh, so you used 523Wh for the journey (divided by 4). Your wattmeter says 240Wh used from your battery, which means your motor contributed 144Wh (divided by 1.67). Therefore, you contributed 379wh (523 - 144). Say it took you 2hours. That would mean that your aveage power was 189.5W (379÷2).

The calculation is only approximate, but it should give a good comparison between different journeys. Use a spreadsheet like Excel to do the calculation, then you only have to enter the Wh from the Wattmeter and the Calories and journey time from ST, and the answer will pop out.

 

[One_Box]

Thanks for that detailed explanation. I'm sure Chris.mitu will find it useful.
Personally I've never used Sports Tracker so know nothing about it. Does it enable you to input the combined weight of bike and rider into the app before starting ?

 

[oldtom]

There's a couple of screens on the display unit of my Xion PC that depict live-time watts usage, (1) from the motor and (2) from my effort. - completely pointless technology in my opinion.

Try though I may, I really can't think how that kind of information benefits me in any way.

Tom