What is your watt usage at 15 mph?

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Sep 26, 2021
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Mine is less than I expected, around 250ish watts at 15mph on an upright Mtb with 26inch MTB tyres.

Less than I expected because I'm using a Cyclone 3kw mid drive, which I picked up to delete ANY hill, I thought at the expense of piss poor efficiency at low speeds and power output compared to a much smaller 250w motor at the same power levels.

I was going to go dual motor, Cyclone for climbing hills and a small efficiency focused 250w hub motor for cruising on the flat, but with the numbers I'm getting from the Cyclones controller displayed on its lcd this would not give me as much of a drastic increase in low speed efficiency as I would have expected.

Would help a lot if you kind folks could post what power usage you get at 15mph on the flat, so I can get some idea of how this setup compares.

Can you really get considerably less power usage at 15mph on a MTB upright in Tshirt and shorts, by using a motor optimised for maximum efficiency at 15mph on the flat?
 
ebuilder said:
Depends on the bike, weight of the rider, size aka drag of the rider, tire air pressure, even air temperature.
Too many factors to generalize. Even tire compound matters.

Aye, your right. Just wanted a rough ball park idea of what a MTB would use watt wise at 15mph with a motor optimised for the speed.

My bike probably uses a bit more because the all up weight of the bike and rider is 160kg plus my front tyre pressure is set quite low because I'm troubleshooting an issue where the tyre was unseating from the rim at normal higher pressure, but still pleasantly surprised as I was expecting more in the 300/350w range at what I thought would have been an extremely inefficient place in the power band for the Cyclone at 15mph, considering 250w is less than one tenth of the rated capacity.



And yeah, it would be false economy to add a second cruising motor considering the surprising low speed efficiency of the 3KW

You've got me thinking though, there's a lot of steep long hills where I live that I go up and down frequently.
It's easy going up thanks to the mid drive but coming back down is an issue and a conundrum, if I brake gently to regulate speed I'll end up glazing my brake pads and disks, if I brake hard I risk losing grip due to stones and bits of gravel on top of the road surface and locking up the wheels which can get scary.

Can I setup a direct drive to be a pure dynamo and braking system? Something like the 1500w leafbike motors because they have pretty much no cogging resistance.

I know regen braking on Ebikes is pretty ineffectual in actually recovering power back into the batteries, and I think this is mainly down to how most controllers handle regen, because only when the rpm and torque on the motor is high enough to raise the back emf to a high enough voltage to overcome the voltage of the battery can it actually push charge back in.


What I'm thinking of is putting a voltage booster between the battery and controller that will be able to scavenge any voltage the motor can generate and boost it up to charge the battery, should recover a Lot more than usual

But the main function just to regulate speed downhill and save destroying my brakes
 
ebuilder said:
Enjoy the hell out of that big motor and let the big dog eat is my motto.

Oh heck yeah, I love just letting it rip up the steepest hills when nobody is around, WOOF WOOF!



I'm running the stock LCD programmable controller because I like being able to switch between power limit modes depending on what im doing, though you could get away with using the non programmable one as its a lot cheaper.

I like it a lot!
Plenty powerfull for me and not too loud considering the power, downright stealth when running on power level 2/5 when you just want to sneak past folks.

So far I'd say its the best bang for buck mid-drive out there.



I'll probably end up doing the experiments with the direct drive and regen braking anyway at some point, for science!

And if the costs are not worth the benefits I'll just fit it in a second ebike, as I could use a second bike anyway so I've always got a runner while i have the other in bits for upgrades and ect
 
999zip999 said:
Regen 7 to 8% maybe 10% And can make problems elsewhere.
Oh here's a pretty cool video, that probably explains why Ebike regen braking is underwhelming and is mostly a gimmick, because I'm pretty sure that no ebike controllers do anything that is mentioned here: https://m.youtube.com/watch?v=Qvf35ANNC3M&feature=youtu.be



If you use the right kind of electrickery you should be able to get a lot more energy back from the stored potential energy from being at the top of a hill than with the lame ghetto implementations of regen braking usually found in ebikes, in this video, a car recovered around 40% of the energy it used to drive up there in the first place https://m.youtube.com/watch?v=MeocIWk0OOw
 
Well, I can say with certainty that with 20 mph *average*, 24 mph cruising + pedalling I'm using 7.5 wh/mile.

But than, I'm not pedalling 'just for show' and I think I'm contributing at least half of the power, and I have a recumbent (though by far not the fastest and lightest around, quite the other way around).

250w just for 15 mph seems kinda huge, unless you have an upright cruiser with fat tires and one hell of an inefficient motor. You sure your speedo is not off?

Anyway, the fact that 3kw motor would be pretty inefficient when used at low speed is absolutely correct.

Think this way: motors have 'copper' and 'iron' losses (leaving aside very rare ironless and synRM motors not found on bikes).
Copper losses is a function of torque. Iron losses is function of rotation speed - *regardless* of actual load, and the more powerful the motor, the more - it can be minimised by thinner laminations, but cannnot be eliminated so long as you have a typical permanent magnet motor with an iron core. There is also friction losses in reduction gears - which, again, go up with speed.
On a less poweful motor, you are usually seeting about 30 or so watts of losses at high speed, double that for a more powerful motor, very powerful motors can easily get 100+w and 3kw cyclone seems like a really poweful motor.

So, a middrive that drives your *crankarms* usually operates at close to it's maximum rotation speed *regardless* of actual speed, because it is desigend to interface with your pedalling speed.
It makes it deliver monstrous torque when you have low enough gears AND allow extremely high speeed when you have high gears.

However, when puttering along at 15 mph that takes, let's say, 150 real mechanical watts and barely loads the motor - but it still spins at near at maximum speed and wastes 100w to friction and iron losses - resulting in efficiency of about 66%!

Therefore, adding a 250w motor for steady cruising (or a smallish 500w direct drive motor to allow regen braking as well), and engaging the cyclone (it has an overruning clutch between itself and the cranks, I presume, not fixed gear?) only to 'delete hills' or for a burst for 40+ mph speed somehwere where are not pedestrinas and police around is 100% viable strategy.

I did pretty much the same, but with two DIY middrives. I've removed the 'crank drive' for now because gearbox I've bought for that purpose turned out to be quite sucky, but I'll put it back eventually.
 
Regarding regen braking. Indeed, values of around 10% are realistic (unless you have very steep hills around - than you can do quite a bit more, or pedal while regen braking (which I actually do just for the fun of it sometimes :)), and it has very little to do with 'electrickery' actually, even if you'll have 100% efficient motor/controller combo.

You can only recover energy that is stored as potential energy - acceleration to speed, and going up hills.

Energy lost to rolling resistance and aerodynamics will be lost forever, and those absolutely dominate - unless have you a ton of stop and go traffic and very steep hills.

A highly streamlined recumbent/velomobile with efficient tires and rider mostly using motor just to accelerate from a stop, get up hills, and than using regen braking to stop and 'ride brakes' down hill may in fact see 50+% recuperation figures from a controller, but actually less because a motor that has regen braking will have iron losses even when off, unless you have a *manual* clutch of sorts.
 
Just so you have more to compare. I run the BBHSD on an upright country cruiser. 15 mph is my favorite cruise speed. Into a moderate wind (strong breeze?) and I'm pulling 300-350 watts. With a tail wind I'm 0-100 watts. Flat no wind and it's around 100-150 watts.
 
BalorNG said:
250w just for 15 mph seems kinda huge, unless you have an upright cruiser with fat tires and one hell of an inefficient motor. You sure your speedo is not off?

Diggs said:
Just so you have more to compare. I run the BBHSD on an upright country cruiser. 15 mph is my favorite cruise speed. Into a moderate wind (strong breeze?) and I'm pulling 300-350 watts. With a tail wind I'm 0-100 watts. Flat no wind and it's around 100-150 watts.


Around 250 watts seems the baseline for 15mph with 160KG with an upright posture on a Mountain Bike

I actually couldn't get any motor to draw much less using the Grin Technologies simulator here: https://ebikes.ca/tools/simulator.html?mass=160&hp=0&autothrot=false&throt=100&axis=mph&motor=Leaf%205T&frame=mountain&batt=B4816_GA&cont=PR

So the Cyclone does in fact seem just as efficient at low speeds as anything else wierdly enough.

Such low wattage numbers as you are getting, are they from adding pedal input and/or lighter weight and more aerodynamic clothing and tucking in?
 
Gorillazilla said:
BalorNG said:
250w just for 15 mph seems kinda huge, unless you have an upright cruiser with fat tires and one hell of an inefficient motor. You sure your speedo is not off?

Diggs said:
Just so you have more to compare. I run the BBHSD on an upright country cruiser. 15 mph is my favorite cruise speed. Into a moderate wind (strong breeze?) and I'm pulling 300-350 watts. With a tail wind I'm 0-100 watts. Flat no wind and it's around 100-150 watts.


Around 250 watts seems the baseline for 15mph with 160KG with an upright posture on a Mountain Bike

I actually couldn't get any motor to draw much less using the Grin Technologies simulator here: https://ebikes.ca/tools/simulator.html?mass=160&hp=0&autothrot=false&throt=100&axis=mph&motor=Leaf%205T&frame=mountain&batt=B4816_GA&cont=PR

So the Cyclone does in fact seem just as efficient at low speeds as anything else wierdly enough.

Such low wattage numbers as you are getting, are they from adding pedal input and/or lighter weight and more aerodynamic clothing and tucking in?

Well... my overall weight is closer to 170kg, and my position is also quite upright.
https://youtu.be/ia32DlbdzHo
Just bent over the other way around :)

My condition is not stellar this days, so 150 average watts pedalling input is likely an optimistic estimate if my power meter data from winter training is of any estimation.

https://ridewithgps.com/trips/96665315
 
Gorillazilla said:
[It's easy going up thanks to the mid drive but coming back down is an issue and a conundrum, if I brake gently to regulate speed I'll end up glazing my brake pads and disks, if I brake hard I risk losing grip due to stones and bits of gravel on top of the road surface and locking up the wheels which can get scary.

It's almost like you'd be better served by a brake that uses the rim as its rotor, with pads that aren't susceptible to pad glazing. Maybe some enterprising manufacturer makes something like that.

Electric braking uses the backlash in your torque arms to gradually unscrew the axle nuts and then ruin your hub motor and your bike frame. Just so you know what to look forward to.
 
BalorNG said:
150 average watts pedalling input is likely an optimistic estimate if my power meter data from winter training is of any estimation.

https://ridewithgps.com/trips/96665315

Ahh that makes sense now, I'm measuring a pure motor reading with no pedaling input whatsoever to get 250w at 15mph


My power usage goes down to around 100w as well if I add a token amount of pedalling.
 
Chalo said:
It's almost like you'd be better served by a brake that uses the rim as its rotor, with pads that aren't susceptible to pad glazing. Maybe some enterprising manufacturer makes something like that.

Electric braking uses the backlash in your torque arms to gradually unscrew the axle nuts and then ruin your hub motor and your bike frame. Just so you know what to look forward to.


You know, I saw something just like that. Page 56 of the Cyclone thread
file.php
 
Gorillazilla said:
BalorNG said:
150 average watts pedalling input is likely an optimistic estimate if my power meter data from winter training is of any estimation.

https://ridewithgps.com/trips/96665315

Ahh that makes sense now, I'm measuring a pure motor reading with no pedaling input whatsoever to get 250w at 15mph


My power usage goes down to around 100w as well if I add a token amount of pedalling.

Note that I'm riding at much faster speeds though. 23 mph cruising speed uses not just 1/2 of the power, it is nearly tripled, have a look, this is a great model:

https://www.gribble.org/cycling/power_v_speed.html

Anyway, what's your no-load loss, anyway? If you simply put the bike upside down and go full throttle, how much would it use energy?

In my case, my top no-load watt drain is about 50w - but includes reduction losses in belt and wheel acting like a pretty powerful fan while spinning to RPM equivalent of ~32 mph! (that my top speed if I pedal, if not it is about ~30) Pure iron losses are about 30w.

At half this speed it would waste half the watts.
 
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