Again...3T, 4T, 5T, 6T difference

[stancecoke]

In austria the law is quite strict and only allows up to 600w peak/250w continous motor power and max 25 kph speed.

It is 3kw motor .... would run near 80kmh

We are still talking about a mountain bike to be used in Europe in a densely populated city in rush hour traffic?!
I hope you are well insured... :wink:

regards
stancecoke

 

[minde28383]

Indeed, strong frames are preferred for such powers and weight.
Strictly policed regions requires ebike to be less noticeable. I assume that is the reason using mountain frame.
Controller can be set to have few hundred watts.
Setup has potential to be run at power above or within legal limit. Rider can adjust power according location. In city set it to few hundred watts, offroad increase power. With button it is done on the fly.

 

[stancecoke]

With button it is done on the fly.

In the Kunteng-controller-open-source-firmware project I have implemented a "morse code" with the brake lever to disable the speed limit

This helps nothing, it will be illegal in Europe anyway.
We just had a long discussion in the german forum, as the police has stopped a rider with a VanMoof Ebike, that can be switched from EU-mode (25kph) to US-mode (32kph) via a smartphone app...
The VanMoof is very stealthy :wink:

regards
stancecoke

 

[minde28383]

morse code" with the brake lever to disable the speed limit

sounds good.

Experimental vehicle owners exempt themselves from rules, otherwise not good to go.

 

[Sparfuchs]

In austria the law is quite strict and only allows up to 600w peak/250w continous motor power and max 25 kph speed.

It is 3kw motor .... would run near 80kmh

We are still talking about a mountain bike to be used in Europe in a densely populated city in rush hour traffic?!
I hope you are well insured... :wink:

regards
stancecoke

In vienna the traffic is really like a relaxed weekend trip compared to other cities this size :wink:
Also vienna has one of the greatest cycle path networks in the whole world, so its not really like being part of car traffic. Nevertheless you are right, and you should always evaluate the risk and be informed about the law. And AS LONG as nothing happens and AS LONG as you drive reasonable it seems possible to use my bike...with a secret speed switch :lol:

 

[Sparfuchs]

Indeed, strong frames are preferred for such powers and weight.
Strictly policed regions requires ebike to be less noticeable. I assume that is the reason using mountain frame.
Controller can be set to have few hundred watts.
Setup has potential to be run at power above or within legal limit. Rider can adjust power according location. In city set it to few hundred watts, offroad increase power. With button it is done on the fly.

You assume totally right :wink:
For now i have a good mtb but it has no rear suspension and the dropout might be to weak for the torque.. even with torque arm.
Thats why i'm looking for a stable dhb.
i already installed a hidden 3 speed switch and with the new controller i can modify how much power speed 1,2, and 3 has 8)

 

[markz]

No need to read through the myth crushing thread, there is a video on it.

https://youtu.be/c96n0Ma2rLY?t=8174

...
If you will get fast winding your will have less dynamic ride than you would have with 5T or 6T.
If you get slow motor 5t or 6t you will get better dynamic with you weak battery.
...

As far as I understand and having read though the "myth" crushing threads; a faster wind or low turn count doesn't demand more current from the battery pack. It demands more phase current from the controller; which is done with the same input (battery) power.

Nop, because one lives in material world with predetermined conditions like readily available controllers, popular battery voltages.
These myth busters never tried any of these motors but have pencil and paper and few physics books.

by post edit I extend myself little bit more. What I mean by 'predetermined'. We have readily available controllers and they perform as they do perform and result is that slower motor is more dynamic in slower speeds. Vast majority is using Sabvoton and Kelly with 3kw hubs. We are talking about 350a and 300a phase.
Also worth mentioning that battery amps is also the factor, not only phase current as you mentioned. Talking about slow speeds and starting from stand still. With fast wound motor you draw more amps from battery because you set more amps on your controller to achieve the same expected performance from stand still.

 

[minde28383]

This video won't open Pandora to newcomers, because it contradicts to what other say and experienced. In theory it is correct what video says but few factors needs to be considered. Newbies have troubles differentiating between various parameters and option to choose therefore will will read and watch tons anyways. Saying to them that slow and fast wound motor version has the same torque is true but unfair, because in the field they will get different performance out of different motor versions.

The key is to understand that several factors "motor, controller, battery (bms)" are in play, also driven wheel size matters. You can't take out of equation rest and say that faster wound motor has the same torque and efficiency as the slower wound motor version. In theory it might have the same torque, but in reality you won't be running that motor in bench in laboratory with difference voltages according T motor version. Fast and slow motors perform differently in ebikes, with controllers people can acquire, and batteries they will have.

You decide on voltage you will be using, lets say 60v, 72v, or any other different nominal voltage you require, get controller and battery accordingly. Determine your max speed you need to be riding and choose motor accordingly.

 

[Ls6s]

The single best thing always with a DD hubmotor for performance is to run as small a tire as you can live with. Sure it makes getting the eye appeal a little more difficult, but with the kind of power you're talking about pedaling the bike is a bit silly...like having functional pedals on a motorcycle. That means you can run a somewhat smaller tire on front too and put shorter cranks so you don't have to worry about pedal strike.

The QS205 V3 is a better motor than the others you discussed because it has a significantly lower slot and pole count. Where that helps is having less iron core losses at higher rpms.

Regarding the winding choice, just make sure you get one with a low enough turn count that you can go as fast as you'd ever want with a battery voltage of a 22s pack and that small wheel. That gives you more options for controller later on to get the most out of the motor. All the different winds available for a motor have the same torque potential and make the same heat for a given amount of torque. That's why a smaller wheel on a hubmotor always outperforms a larger wheel, because it lowers the gearing providing you with more thrust and a cooler motor. Personally I always go for the fastest wind (lowest turn count) of any motor, and I use rims and tires with a 22" OD or less (19.25" OD on all each of my ebikes that have over 100mph top speed. That way I can run lower voltage on bikes that don't need highway speeds. It does require more capable controllers in terms of current, so I never come up short in terms of acceleration, but it gives me the flexibility for maximum performance for a given motor.

what do you think about the 3.5t in 16" ? i mostly drive on roads but the region has a lot of hills, do you think 3.5t in combination with 16 inch has good torque ? i was thinking about the 4t with 16" but i think with 72v without flux, the top speed will be a bit too low for me, i'm thinking about 75-85 km/h. I have max 150amp controllers

 

[Chalo]

what do you think about the 3.5t in 16"?

John in CR hasn't been posting around here for some time.

Use 4qd.co.uk's road speed calculator to figure out what RPM you're looking for at your desired top speed.

Vehicle Road Speed Calculator - 4QD - Electric Motor Control

This is a JavaScript page that helps you calculate the roadspeed of your vehicle.

www.4qd.co.uk

Then use Kreuzotter's speed and power calculator (with realistic assumptions about the parameters) to determine how much power you need to attain your desired top speed.

Bicycle Speed (Velocity) And Power Calculator

Bicycle Speed (Velocity) And Power Calculator, comparing different kinds of bicycles

www.kreuzotter.de

Then use the Grin simulator to integrate motor winding (RPM per volt) with controller voltage and current variations until you find a combo that outputs the power you need at the RPM you need for your desired top speed. Motor winding can trade off against battery voltage to deliver the same RPM, and controller current can trade off against motor winding to deliver the necessary torque at that RPM to meet the power requirement.