25km/h? 32? 45? 60? What speed do you *actually* want on your e-bike?

[Cheese]

How is a 250w e-bike detuned to go 20mph vs a 500w 20mph bike?

I have it in my mind, that a 500w bike is better for a heavier guy like me, and would just be all around better ride.

 

[AHicks]

To my way of thinking, "de-tuned" is kinda looking at it the wrong way. The fact is, it can make full power UNTIL it hits an electronic limit (20mph) that's been placed on it. So in effect, it's governed, not de-tuned.

All else being equal, I agree the 500w works better than a 250w for a bigger guy. How that might make it "better" all around is going to depend on a lot of factors. Consider for instance a light weight rider who may have no use for any more than 250w?

 

[indianajo]

Consider for instance a light weight rider who may have no use for any more than 250w?

I'm down to 160 lb and find 1200 W geared hub useful up several 15% grades in my route. I added four such grades and 2.5 miles to avoid riding the deteriorating 11" wide berm on state road 3 to my summer property. 3.5 hours commute is entirely enough exercise, I don't want a 250 W mid drive whirring me up the hills at 2 mph. Fortunately 1200 W kits weren't illegal when I bought.

 

[Mass Deduction]

[...]I have it in my mind, that a 500w bike is better for a heavier guy like me, and would just be all around better ride.

*scratching my chin*

I don't understand this focus on wattage. A 10 watt LED lightbulb can produce more light than a 60 watt incandescent lightbulb. It's not about watts, it's about how much power created per watt. I like the example of the Shimano E6000 motor being replaced by the E6100. The torque went up 20%, and the range went up 25%, on the exact same battery. Average power draw went down, but actual force generated went up.

Surely the holy grail is more torque and more range at lower wattages? Why do we want to drain our batteries faster? It makes no sense to me. I want sufficient torque and range, and I want it at the *lowest* wattage I can get it. More torque per watt means longer range, smaller/lighter batteries, less expensive systems, etc. Higher wattage means heavier/more expensive batteries and lower range.

Surely we want more efficient motors with each new generation, not motors that just drain the battery packs faster.

[...] I don't want a 250 W mid drive whirring me up the hills at 2 mph. [...]

Aren't most mid-drives variable wattage? For example, as low as 250w on the flats, but as high as 500w when hill-climbing?

 

[AHicks]

*scratching my chin*

I don't understand this focus on wattage. A 10 watt LED lightbulb can produce more light than a 60 watt incandescent lightbulb. It's not about watts, it's about how much power created per watt. I like the example of the Shimano E6000 motor being replaced by the E6100. The torque went up 20%, and the range went up 25%, on the exact same battery. Average power draw went down, but actual force generated went up.

Surely the holy grail is more torque and more range at lower wattages? Why do we want to drain our batteries faster? It makes no sense to me. I want sufficient torque and range, and I want it at the *lowest* wattage I can get it. More torque per watt means longer range, smaller/lighter batteries, less expensive systems, etc. Higher wattage means heavier/more expensive batteries and lower range.

Surely we want more efficient motors with each new generation, not motors that just drain the battery packs faster.



Aren't most mid-drives variable wattage? For example, as low as 250w on the flats, but as high as 500w when hill-climbing?

My thought regarding higher wattage motors - assuming the motor has been rated by it's ability to dissipate heat - NOT add hype/wishful thinking.

ALL else being equal, if we compare a 250w motor with a 500w for instance, both motors will draw the same amount of power/wattage up to the point the 250w is running at max available torque. At that point, the 250w is not able to produce any more (without going into an overheat scenario), but the 500w is only running at half available. It's only when the 500 is operated at a higher wattage that it's using more power than the 250w. So bottom line, each will use the same amount of power until the 250 is all tapped out, where the 500 will just be starting to warm up....

Regarding mid drives being variable wattage, no rocket science here. The motors are no different than any other brushless motor. You control the amount of power they're making with the amount of power you're feeding them. -Al

 

[Nutella]

I'm happy with riders having the ability to ride as fast as they want as long as it is in an appropriate place. A street or empty bike path, go right ahead, if you crash and hurt anyone, it'll just be you. On a bike path with people on it, even 15 or 20mph might be too fast. Pedestrians are erratic, it's too easy for someone to turn and step right into your path.

 

[Mass Deduction]

My thought regarding higher wattage motors - assuming the motor has been rated by it's ability to dissipate heat - NOT add hype/wishful thinking.

ALL else being equal, if we compare a 250w motor with a 500w for instance, both motors will draw the same amount of power/wattage up to the point the 250w is running at max available torque. At that point, the 250w is not able to produce any more (without going into an overheat scenario), but the 500w is only running at half available. It's only when the 500 is operated at a higher wattage that it's using more power than the 250w. So bottom line, each will use the same amount of power until the 250 is all tapped out, where the 500 will just be starting to warm up....

Regarding mid drives being variable wattage, no rocket science here. The motors are no different than any other brushless motor. You control the amount of power they're making with the amount of power you're feeding them. -Al

I can't disagree with anything you say, but it's an incomplete assessment IMO. What if that 250w motor is super efficient, whereas that 500w motor is less efficient and produces less speed/torque at 500w than the other does at 250w? Again, the LED vs. incandescent lightbulb example. An incandescent lightbulb is mostly good at wasting power as heat, whereas the LED lightbulb is very efficient at producing light.

Back to the example of Shimano increasing torque 20% while also increasing range 25% from one generation to the next (on the same battery). These efficiency gains aren't just theoretical, they're very real.

Give me the most efficient motor, at the lowest wattage possible, that will do what I need it to do. Every time.

 

[AHicks]

I can't disagree with anything you say, but it's an incomplete assessment IMO. What if that 250w motor is super efficient, whereas that 500w motor is less efficient and produces less speed/torque at 500w than the other does at 250w? Again, the LED vs. incandescent lightbulb example. An incandescent lightbulb is mostly good at wasting power as heat, whereas the LED lightbulb is very efficient at producing light.

Back to the example of Shimano increasing torque 20% while also increasing range 25% from one generation to the next (on the same battery). These efficiency gains aren't just theoretical, they're very real.

Give me the most efficient motor, at the lowest wattage possible, that will do what I need it to do. Every time.

I was working with today's reality. I think we ALL look forward to lighter, more efficient motors AND batteries!

Fresh in my mind was what turned out to be a much bigger upgrade than what I expected. I swapped a 1500w direct drive for a 1000w gear drive. No other changes so a direct heads up comparison. Not only did I pick up the big performance increase I expected at the speeds I spend most of my time riding, there was an unexpected bonus as I went from a 25 mile battery range to a 35 mile range!

Point being, wise choices made powering your bike can be a really big deal....

Still no magic regarding mid drive motors. -Al

 

[Stefan Mikes]

Still no magic regarding mid drive motors.

Only these allow climbing hills at far lower motor power.

 

[AHicks]

Only these allow climbing hills at far lower motor power.

All due respect, that's about gears, not the motors!

 

[steve marino]

20 MPH is plenty. What I want is more range. As someone so wisely pointed out on this forum, if you're going 30+ mph on a bike, you are probably going to get killed by a car driver because they don't expect a bike to go that fast, they're familiar with 20 MPH, tops, and will judge their distances and reactions accordingly. It makes a LOT of sense to me. Look, you know they're going be fooling with their phone and turn in front of you anyway, right? Would you rather that happen at 20 MPH, or at 30 MPH? There are no do overs in the morgue. This life ain't a trial run, this is it.

 

[JGcycle]

I feel that 40 KPH is plenty fast enough for me--being an old fart and all.

 

[tomjasz]

I feel that 40 KPH is plenty fast enough for me--being an old fart and all.

Agreed. But. Too fast for me. Reaction times in my 70s are more appropriate for 15-20mph. Too many eBikes that will roll at 28 mph won’t brake at appropriate levels. But ignorance is bliss for many of us.

 

[Deacon Blues]

I feel that 40 KPH is plenty fast enough for me--being an old fart and all.

40kph is fine for me too. I only go that fast on rural highway roads, with few cross roads. In town I ride in the 27-31kph range.