Electric bike conversion kits - more advice please re drag, noise, robustness, etc.

[Cyclezee]

QUOTE=Oiseaux;109447]To a novice like me that seems pretty impressive.

What is the total weight of a kit, everything included.

Oiseaux[/QUOTE]

Hi Oiseaux,

That was my first ever Youtube video, a lot of room for improvement there.
A standard kit as seen in the image below weighs from 7 to 7.5 Kg, the variation is due to things like wheel size, whether the brake disc rotor is fitted or not etc. I have just realised that the included 180mm brake disc rotor is not shown here.

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[NRG]

Oh well, seems both my Bafang motors are better than Jerry's toxgin and I wont be buying an eZee kit!

 

[Oiseaux]

Hi Oiseaux,

A standard kit as seen in the image below weighs from 7 to 7.5 Kg, the variation is due to things like wheel size, whether the brake disc rotor is fitted or not etc. I have just realised that the included 180mm brake disc rotor is not shown here.

View attachment 2318​

Thanks. To sum up, my existing wheel weighs 1.7kg, so for the largest kit I will be adding an extra 5.8 kg (7.5 kg - 1.7 kg) to my existing tourer wight of 17.3 kg to give me a total weight when kit fitted of 23.1 kg. Is this correct ?

NRG For the benefit of myself and others could you explain your recent posting in more depth please.

 

[Cyclezee]

Hi Oiseaux,

Those calculations are basically correct. The eZee kit comes with a Schwalbe Marathon Plus tyre which is probably heavier than yours, a front wheel kit has more cable than a rear, so there are a few variables to take into consideration.

 

[NRG]

NRG For the benefit of myself and others could you explain your recent posting in more depth please.

Sure! Alien GSII spin wheel up under power to 18.3mph time for it to stop 65 seconds. Thats better than the two examples given above. So it must have less drag right!?

The motor on my Peugeot takes about 75~80 seconds for the same test and from a similar speed.

 

[jerrysimon]

So it must have less drag right!?

lol, it was fun though NRG

Jerry

 

[Oiseaux]

Sure! Alien GSII spin wheel up under power to 18.3mph time for it to stop 65 seconds. Thats better than the two examples given above. So it must have less drag right!?

The motor on my Peugeot takes about 75~80 seconds for the same test and from a similar speed.

Hmm, those spin times you quote seem to speak volumes, presumably both motors are Bafangs, is there a model number ? Can you offer an explanation as to why both Bafangs that I have tried were like cycling through mud when the motors were turned off.

Oiseaux

 

[Oiseaux]

On Endless-shere.com thread about half way down it says

"Now lets set the record straight! If you have cogging torque of any kind, then you have an improper motor/controller application!
The motor timing to the controller is wrong! I heard alot about "cogging torque" but it is all BULLSHIT!
If your motor resists at all, even in pulses, then the timing is off! If you can reprogram like the infineon then all is good.
I've had this "cogging effect" by using mix match motors to controllers. tHIS IS NOT NORMAL FOR AN E-BIKE!
If you have any cogging whatsoever then your setup is wrong and you are losing speed and effientcy."

Could this be an explanation as to the anomaly of individual experiences concerning drag on the Bafangs ?

With regard to spinning times, the same poster goes on to say;

"The geared weight of the spinning components is what keeps this spinning so long.
No load means absolutely **** for how a hub motor performs."

which is what jerrysimon was referring too.

 

[flecc]

No, cogging refers to when a motor is engaged all the time, such as in a non freewheeled hub. The drag being experienced is on freewheeled hubs when the motor is out of play as when pedalling without power.

 

[Scottyf]

Not sure why I keep reading this thread its like going round in circles.
If you buy an electric bike chances are you are going to use the electric.

Most journeys unless touring are under the max range of most journeys so even if there is drag it shouldn't be a issue.

 

[flecc]

For a lot of users I agree Scotty, but some like the pleasure of traditional cycling without power when the going is easier. That's when I loved my old 22 kg Lafree most, being able to cycle on the occasional flat route unpowered at normal cycling speeds up to 19 mph without any extra effort over a normal bike. It wasn't a range issue, just a pleasure one. Cytronex owners know what I mean.

 

[Oiseaux]

Not sure why I keep reading this thread its like going round in circles.
If you buy an electric bike chances are you are going to use the electric.

My first posting says;

"My latest thinking has been to use the kit on my tourer in the summer where I would expect to use electrical assistance for about 20% of a ride, and on my off road in the winter for larking about on the bridlepaths which start outside my gate and where I would expect to use continuous electrical assistance."

So for me old chap the question of drag with motor off is an issue, as it is for many others. If there is an explanation for the anomaly of individual experiences regarding the Bafang I would suggest that is contributing to the knowledge base, wouldn't you !!

 

[Scottyf]

Would it not be better though to just remove the additional weight and say pedal the extra 20% needed without electrical assistance and not have to worry about drag at all?

 

[flecc]

Would it not be better though to just remove the additional weight and say pedal the extra 20% needed without electrical assistance and not have to worry about drag at all?

Weight effectively makes no difference on the flat though, since it's not being lifted. It's effect on rolling resistance is nil if the tyre pressures are correct for the total weight.

It only affects climbing to any extent where it constitutes weight lifting.

 

[Scottyf]

Indeed I understand about the forces of weight on acceleration and hill climbing. However on this instance the use is only requiring 20%. What would the 20% use consist of?

Is it a continued use of light assistance, or just when there's a hill only and then riding along without assistance all other times?

 

[flecc]

Usually hills, the Cytronex users often use their power that way to get decent range from their tiny battery, and that was the way I used my Lafree, and even the Agattu when on some tests.

 

[Andrew harvey]

Spent this morning swapping wheels tyres and rolling down a hill. The conditions were not ideal with the wind gusting but the hill was long enought to reach terminal velocity for the slope.
The only measurable difference in speed in speed can state is that my trike is 2 to 3 mph faster than my upright. With or without the motor the upright was peaking at 25mph and the trike 27.5. Both of these bikes use modern motors which may be better built than the older versions.
This afternoon on a whim I swapped my 7 speed Nexus, on my upright, for an 18 tooth single speed, I admit I didn't try any hill climbing as i'm running a 44/52 combination at the front, but on the flat with no power it made a bigger difference than replacing the front motor.

Just a question Flecc, if the use of nylon gears reduces the efficiency of the drive by 12% and the use of epicyclic gears reduces the efficiency by a further 12%, surely that should mean that any motor using this combination should run at an efficiency at least 24% lower than other system. This means they should output less power eat more current and have far lower ranges.
Why is that when I'm riding with a Panasonic powered friend I can keep pace with him and manage the same range? perhaps I'm just a really strong cyclist.

Further
I was invited out to visit a group of recumbent riders on the Satuarday of the Prestigne weekend. I had fitted SB motors for a couple a month or so ago and whilst awaiting the 12AH batteries I considered the best option for them I fitted a c 8AH Sunlova packs. I got to the campsite around 6 pm after I had shut my shop. They had ridden in convoy about 12 bikes in all from Shiffnal to RAF Cosford to visit the museum and back. The trip was 31 miles both Frank and Val had 3 out of 4 leds left on the battery indicators. Val is 75 years old whilst Frank is 79. Now I hate to labour the point but if there was a significant drag on the new motors they might have noticed. To get the sort of range they, I and a few other Bafang riders get you have to use the motors for hills and occasion relief only.
I have rang Frank to see how he is getting on know he has his 12 AH battery pack,
lets just say he's pleased, I asked him if he can feel any drag, he's answer was "why, should I?"

Flecc
Now I know I am unlikely to convince some riders here about the low drag of these new motors, so how about a road test. I know you live down south somewhere but if I can get my trike down would you fancy doing the honours.

 

[flecc]

Regarding the 24% lower efficiency Andrew, 75% is a typical SB hub motor efficiency. Only teasing of course, that's not the whole story.

You've proved the point I've made previously though, for those riders including the older ones to ride like that and get that range, they were clearly very fit. This cropped up recently with d8veh who also insists there's no drag and with his SB motor apparently gets 70 miles range from 360 Wh, roughly 5 Wh per mile.

These are very unusual figures, most people don't get anywhere near that low consumption. Even a very strong rider like David Henshaw doesn't get anywhere near that with hub motors. He got 16.4 Wh per mile on his Torq 1 on test in the flat Somerset levels area when five years younger than now yet was strong enough to be the race winner at Presteigne that year. Previous query threads in this forum on consumption show members reported figures ranging from 9 to 24 Wh per mile, but most commonly around 12 to 14 Wh per mile on SB hub motors.

Therefore it's little wonder that riders strong enough to use only 40% of the current of the average will not be so sensitive to drag, so a test against those who cannot do that is pointless, comparing oranges with pears. If I'd been riding with you my larger battery would have been exhausted before the end of the ride since I'm only an ordinary mortal who needs to use some power all the time on the hub motor bike, due to it being a pig to pedal with the SB motor in as I previously posted.

I repeat, I experience unacceptable drag. Large numbers post in this forum that they do also. If you and others don't, fine, I'm pleased for you all, but that doesn't make my experiences go away, or any others negative experiences.

Simple question. The Tongxin Nano motor is very widely accepted to have the lowest unpowered drag of any hub motor. If it has the lowest, the SB motors must have more, yes?

Ergo, not zero drag.

After all, if the Tongxin were not very superior in this respect, why would so many buy it knowing as they do it's poor record of reliability against the SB motors?
.

 

[NRG]

Well the thread has moved on but my tongue in cheek post previously was to highlight that the spin down 'test' proves nothing as the mass of the wheel especially out toward the rim will skew the results. I consider myself to be pretty fit but still find the Alien tough to ride without power (the Peugeot is better) and yet the PCS is a joy in comparison....something is going on...the Peugeot with an ordinary wheel rides like the PCS or is it the other way 'round...

 

[flecc]

Exactly NRG, something is indeed going on, for my experience mirrors yours and many others. We commonly find the bikes with Panasonic units and the Tongxin motor to be much easier to pedal than in many cases with SB motored bikes.

When I ride three miles on my one flat route without power for pleasure on a Panasonic unit bike, but cannot even contemplate that on either of a choice of SB motored bikes, it's not my imagination, it's fact.