Peeps, I need help with finalizing a choice for a motor, QS205, anything better?

[MadRhino]

Limited to 25kw short bursts and 4kw continuous. Higher weight and/or aero drag, along with slower riding habits, would require setting lower limits.

 

[John in CR]

Get a 3t in a 13" scooter rim, which works out to a 19.25-20" OD wheel depending upon the tire you buy. That or a fast wind 273 if you want to go spokes and a bit larger wheel like a 17". If all your riding is on roads that are in good condition, then the size of the wheel and weight of the motor don't really matter. I run almost exclusively 13" scooter wheels with motors that weigh 15.5kg before the relatively heavy tire and allow mag rim, and while the tire can skip a bit on choppy roads, the tire size and motor weight are really a non-issue. I too live in a mountainous country and have the fastest bikes on the forum.

You haven't mentioned what all up load (bike+rider), which is of critical importance.

Hey mate, all up the weight would be 70 kg plus 60 so 130 kg all together.

I've never considered going down to a such a small size, I wonder if it will look strange compared to the front wheel.

I really would love to use the QS273 but it seems like the added weight causes too many issues especially off road on trails, i'll also have to invest in stronger overall components so the cost may sky rocket.

For a single person weighing 70 kg I would think that the QS205 motor is the best option.

Now you throw in that it's for off-road too. Just make sure you have a setup with thermal roll-back and thermal cutoff, because you're in for a strong dose of reality. These people bragging about what their hubmotors can do in relatively large wheels have never had their ebikes anywhere near the continuous climbs you're talking about. Plus you want high speed too, and now you want it to be good for offroad riding too. You really need to be thinking mid-drive and something a lot closer to the emoto end of the spectrum just to carry enough battery for useful range in those conditions.

 

[E-HP]

We've got very steep hills around here, majority being between 10 and 12 degrees (around 18%).

Another way to ask the question, with a QS205 coupled to a 17" wheel, what is the worst gradient it can handle before overheating?

Well 10-12 degrees sounds a lot more reasonable than 45. On your questions, I'd first start with the motor rating, 3000W, the amount of power it can handle continuously. Since motors aren't 100% efficient, part of that 3000W is heat, so the continuous rating assumes that the motor is able to shed that waste heat continuously as well, which is the issue with a hub motor.

So it comes down to how steep and how far, and specifically how far using power over 3000W, and how much over 3000W. You could add hub sinks and statorade, which will shed some of the heat, and effectively increase the 3000W rating, but I suspect you will still be looking at how steep and how far.

You describe steep hills, and hubs can do steep hills as long as there's time in between to let the motor cool. Does great on rolling hills, in other words. I wouldn't use a hub motor for mountains. But what you call a hill vs mountain may differ from what I or others think. So on the hills, are you talking about 20% for an hour or two, or 20% for 10 minutes? What does "extended period of time" mean?

Even though the Grin simulator doesn't mode the QS motor, you might still benefit from playing with the parameters on a similarly efficient 3kW motor to see what various voltages, currents, and wheel sizes look like on different grades. Looks like the MXUS 4504 with statorade, for instance, can handle up to 24% continuously (250A controller, 72V), but fall short of your speed desires on flat ground:

https://ebikes.ca/tools/simulator.html?motor=MX4504_SA&batt=cust_72_0.2_40&cont=cust_250_500_0.03_V&hp=0&wheel=17i&grade=24&axis=kph

https://ebikes.ca/tools/simulator.html?motor=MX4504_SA&batt=cust_72_0.2_40&cont=cust_250_500_0.03_V&hp=0&wheel=17i&grade=0&axis=kph&cont_b=cust_250_500_0.03_V&motor_b=MX4504_SA&batt_b=cust_72_0.2_40&wheel_b=17i&hp_b=0&grade_b=20

You could try different winds of the MXUS in the simulator to get an idea about the trade off between top speed and ability to climb without meltdown.

 

[John in CR]

...You could try different winds of the MXUS in the simulator to get an idea about the trade off between top speed and ability to climb without meltdown...

I don't know how many times I need to tell you guys before it will soak in...Winds don't make any difference at all other than to change the combination of voltage and current to achieve exactly the same result. Due to the inherent voltage limitations of common controllers the only difference is that slower winds are slower lower power motors. They don't climb hills any better and they don't make more torque. In fact it is more common for a slow wind motor to get burned up, because their current limits are so much lower that it's easier to burn them up.

 

[E-HP]

...You could try different winds of the MXUS in the simulator to get an idea about the trade off between top speed and ability to climb without meltdown...

I don't know how many times I need to tell you guys before it will soak in...Winds don't make any difference at all other than to change the combination of voltage and current to achieve exactly the same result. Due to the inherent voltage limitations of common controllers the only difference is that slower winds are slower lower power motors. They don't climb hills any better and they don't make more torque. In fact it is more common for a slow wind motor to get burned up, because their current limits are so much lower that it's easier to burn them up.

If the students aren't learning, then the teacher should change the delivery method. But, there are some folks that learn hands on, so the simulator is a great tool for that.

Maybe a scenario where the winding may make a difference. Some people ride with other people and/or don't want to blast up a hill at full speed. If you have a fast wind and your buddy has a slow wind, you may want to either ride way faster and say "sorry buddy, I'll catch you at the top", or you may want to ride along at the same speed. But, because you're motor works more efficiently at higher speeds, your motor melts down 8 minutes later, and then your buddy ends up waiting for you at the top as you push your bike up.



https://ebikes.ca/tools/simulator.html?motor=MX4504_SA&batt=cust_72_0.2_40&cont=cust_250_500_0.03_V&hp=0&wheel=17i&grade=15&axis=mph&cont_b=cust_250_500_0.03_V&motor_b=MX4506_Ferro&batt_b=cust_72_0.2_40&wheel_b=17i&hp_b=0&grade_b=15&bopen=true&autothrot_b=false&autothrot=false&throt=100&throt_b=100

 

[ZeroEm]

The QS205 is a 50mm wide motor is it not. The Cromo was made to pull the mountains and it's a 50mm, would that not be a closer match to compare?

 

[MadRhino]

The QS205 is a 50mm wide motor is it not. The Cromo was made to pull the mountains and it's a 50mm, would that not be a closer match to compare?

The cromotor is the QS205, only mod in Croatia to shave some weight off.

 

[ZeroEm]

Learn something everyday, is life not grand! Thx.
Remember reading that like 2 yrs ago.

Cromo Motor

 

[markz]

Move the 04 motor's throttle in the sim down to 71% and the curves and speed are the same.

https://ebikes.ca/tools/simulator.html?motor=MX4504_SA&batt=cust_72_0.2_40&cont=cust_250_500_0.03_V&hp=0&wheel=17i&grade=15&axis=mph&cont_b=cust_250_500_0.03_V&motor_b=MX4506_Ferro&batt_b=cust_72_0.2_40&wheel_b=17i&hp_b=0&grade_b=15&bopen=true&autothrot_b=false&autothrot=false&throt=71&throt_b=100

[attachment=0]
https://ebikes.ca/tools/simulator.html

 

[E-HP]

Move the 04 motor's throttle in the sim down to 71% and the curves and speed are the same.

https://ebikes.ca/tools/simulator.html?motor=MX4504_SA&batt=cust_72_0.2_40&cont=cust_250_500_0.03_V&hp=0&wheel=17i&grade=15&axis=mph&cont_b=cust_250_500_0.03_V&motor_b=MX4506_Ferro&batt_b=cust_72_0.2_40&wheel_b=17i&hp_b=0&grade_b=15&bopen=true&autothrot_b=false&autothrot=false&throt=71&throt_b=100

[attachment=0]
https://ebikes.ca/tools/simulator.html

Ya, I messed up on the throttle setting.