do you like this kind of electric bicycle kit

[evaleto]

Hi all,
With a friend we are building a electric bicycle kit for a specific use case. We are not the first with this approach, but we are curious how people like the idea. Our model is approaching the cytronex concept, here is our bicycle kit,
- keep the bicycle minimal and beautiful,
- our electric bicycle kit doesn't overcharge the bicycle, without battery or energy you can still use your bicycle,
- the hub motor is small with a power from 190W to 250W for less than 2.5kg,
- no pedal assist, no useless wire, you press a boost button (wireless) when you need help, the release of the power is managed automatically with some electronics,
- the battery is small 1kg 36V 6Ah, it's ok for 20miiles,
- the packaging of the battery is customizable, with several color choice and package layout,
- with our tiny charger you can carry it everywhere to recharge the battery on demand,
- the kit construction will be available on opensource license

Any comment will be really appreciated,

olivier

 

[JennyB]

And the use case is....?

 

[evaleto]

And the use case is....?

Sorry,
- maintain the bicycle as normal, don't be bothered by the kit, get assistance only when you need it,
hope, that's better

 

[adrian_sm]

Yes I believe there is a market for light weight occasional assist ebikes. I am also pursuing developing a product for this market, but aimed at high power levels.

- no pedal assist, no useless wire, you press a boost button (wireless) when you need help, the release of the power is managed automatically with some electronics

Why wireless? I prefer only having one battery to charge, and everything running off of it.

- the battery is small 1kg 36V 6Ah, it's ok for 20miiles,

Is this a wish, or reality? Even LiPo would weigh in at ~1.4kg for 36V 6Ah, and that is without any mounting hardware etc.
Have you got more details on the battery?

Good luck. I love the idea of keeping a bike a bike, but with an option of an assist when you want it. It is quite a different riding experience.

- Adrian

 

[neptronix]

What kind of battery is this? a 5ah 10S lipo weighs like 1.3-1.4kg. This would be a higher density cell chemistry than lipo, which is unheard of.

250w is useless for an assist, plenty of kits like that exist already. They are only popular in places where 250w is the legal limit.

 

[Rifle]

I've had somewhat similar thoughts when thinking of what kit would appeal some one who bikes everywhere w/ needing assistance and it was somewhat like this, but much higher power. If you're going to add power to a bike it needs to contribute in ways pedal power can't. Like getting you up a hill w/ out breaking a sweat, or letting you go faster to be at a speed closer to the flow of traffic. The main thing would be keeping the motor as light as possible, and having it freewheel very well. This way the bike can be ridden w/ out a battery and it won't be that bad.

 

[evaleto]

Is this a wish, or reality? Even LiPo would weigh in at ~1.4kg for 36V 6Ah, and that is without any mounting hardware etc.
Have you got more details on the battery?

Yep, the panasonic NCR18650A has 3.1Ah for 2C, you get about 253Wh/kg that is pretty good but only for 250W max (12A peak)

Why wireless? I prefer only having one battery to charge, and everything running off of it.

This is a good question, battery is an issue, but wire sucks also. I did some basic math and with a good power management the button could live more then 2Years.

If you're going to add power to a bike it needs to contribute in ways pedal power can't.

To reach comfort, freewheeling, free weight and small battery, 190W - 250W is important, someone else think that power will not be enough ?

 

[dogman dan]

For a pedaler, 200 watts assist is a huge boost. To the why pedal crowd it's a joke. Just depends on your outlook. For you, it sounds like a perfect approach. A bit much to my thinking though, to mind a throttle wire. Weigh a normal throttle, its pretty light compared to the weight of phase wires to the motor. Just locate the controller closer to the motor for much more weight savings than no throttle. Worth it too, to be able to use half throttle, and only 100 watts.

I fall smack in the middle, I love 500-800 watts continuous, and love pedaling. The pedaling I do is joke of course, adding nearly nothing. At best, I boost my speed 1 mph pedaling. But it makes me feel good. When I don't feel good because I'm old now, I'm free to not pedal for a mile till I feel good again.

On dirt, the bike is totally different, and the ride too. I pedal only when I must to get up a crazy steep incline, and burn a zillion calories just hanging onto the thing. Just like riding motocross is a huge workout.

 

[hekdude]

If you could get the power though gearing, it may be more helpful. (ie. you can change gears)

 

[neptronix]

I pedal like a madman and found my old 250w nominal ( bursted up to 500w ) motor to be almost useless on the hills i have to tackle.

I think you will find interest in battery packs made out of those new panasonics if the price is reasonable. 2C cells that are light = good stuff.

 

[adrian_sm]

To reach comfort, freewheeling, free weight and small battery, 190W - 250W is important, someone else think that power will not be enough ?

It all comes down to the legality issue. If you want to be legal, you have to limit power down to these sorts of levels for many markets.
If you don't care about the legal limit, then you can still build a kit of similar weight, comfort, freewheeling with much higher power levels. I did.

 

[JennyB]

I pedal like a madman and found my old 250w nominal ( bursted up to 500w ) motor to be almost useless on the hills i have to tackle.

Big hills, heavy bike, the rider will never be able to contribute enough to keep a small hub motor in the sweet spot. But this might be just the thing for a lightweight lowland lycra who can't go as far and as fast as they useta. "Motor - what motor? That's my hub dyno!" :wink:

I think you will find interest in battery packs made out of those new panasonics if the price is reasonable. 2C cells that are light = good stuff.

A lightweight, quiet and reliable charger that could charge at 2C would be a real game-changer.

 

[evaleto]

To reach comfort, freewheeling, free weight and small battery, 190W - 250W is important, someone else think that power will not be enough ?

It all comes down to the legality issue. If you want to be legal, you have to limit power down to these sorts of levels for many markets.
If you don't care about the legal limit, then you can still build a kit of similar weight, comfort, freewheeling with much higher power levels. I did.

Are you the man of cummuterbooster? huge respect for your work, I read your website and I'm impress by your work!

Except the legal issue, the problem with your motor is the type of battery that needs much more than 2C. For 250W HUB motor, I have 14Apeak limitation with 10S2P of panasonic. 300W is already not safe - I think.

 

[adrian_sm]

Yep. Thats me. Was trying to avoid mention of my drive on your thread.

Battery is not much of an issue. Heaps of cells can do it if you want the high power. Even one of these $35 LiPo packs can dump 2000w. But realiticlly you would use two to give you decent range.

And if you just want lower 200w power limit, then a 10ah pack at 1c will give you an hour of assist. Any old battery will do that.

Of course they are not quite as energy dense as the cell you picked, but your cells power density is way fom being the bet choice. For a low power system like you are propsoing though, not a bad choice.

 

[evaleto]

Thank you all for your feedback, it's really appreciated

So it seems that 250W really sucks! Many of you gave me the same issue, 250w is useless for the hill. It's a hill issue? To be sure that I understand well, what kind of hills are you talking about? My city is almost flat, hill are long (1miles) with small inclination or short (0.1miles) with high inclination, I'm not sure about the angle.

olivier

 

[JennyB]

Thank you all for your feedback, it's really appreciated

So it seems that 250W really sucks! Many of you gave me the same issue, 250w is useless for the hill. It's a hill issue? To be sure that I understand well, what kind of hills are you talking about? My city is almost flat, hill are long (1miles) with small inclination or short (0.1miles) with high inclination, I'm not sure about the angle.

olivier

It's a culture thing. If you don't like to pedal much, then 250 watts won't take 100 kgs up a 10% grade. I have a 350 watt hub, and though I can get up the short hill in my avatar, there are some locally where I have to dismount. That will change as I get fitter. i really like the lightweight approach. It kinda reminds me of the line in True Grit "They will not get away from Little Blackie. They're loaded down with fat men and iron!" :wink:

 

[JennyB]

Re: 2C charging and why I think it's a game-changer.

Normally you would only carry one battery, but for an independent tour you could also carry a spare and a charger. Switch batteries when the first runs down, then start looking for a cafe with a charge point (you'll be ready for it after 40 miles). Charge both batteries in less than an hour and be on your way. Repeat at the next meal stop.

Would the Panasonic chemistry be happy with this usage? Even on a tour and riding long every day, each third charge could be a slow balancing overnighter. I suggested using the batteries sequentially rather than in parallel because:

• I know the Cytronex batteries charge fast, but they run hot and after hard use they have to be left to cool before they can be recharged. With this method the first battery is cool at the start of charging, and the second will be ready when the first is done.

• With the right support you can continue riding on the second battery while the first is being charged (either riding a loop or with the help of a support vehicle).

 

[georgefromvt]

Are you trying to compete with Gruber Assist or Shadow E BIKE? Light weight and about 200 watts?
http://www.gruberassist.com/english/product/product-description/
http://shadowebike.com/
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