Toorbough ULL-Zeveigh wrote:LI-ghtcycle wrote:I have to say, if there is going to be a serious race, get ready for the mid-drives to walk away from the hub motors!
mmmkay, don't see how the hub debate was anywhere on the radar to what's being discussed.
but if you really can't help yourself & just have to get in your swipe then i guess i just have to rebut.
the problem with a hubmotor is that it is stuck in one gear, n'est-ce pas?
it's efficient at only one particular rpm.
in normal road racing where speed is never constant, you're relentlessly accelerating (either positive or negative) a hubmotor is at a decided disadvantage.
well, that along with it's higher inertial mass it sucks ballz really.
however in applications that run mostly constant speed without wavering off it's efficiency peak too much is precisely where a hubmotor is in it's element.
that's why a hubmotor works reasonably well for a commuter bike.
the overall percentage of time spent off-peak spinning up to speed is relatively low.
and climbing a mountain is even more steady-state constant rpm than commuting.
the terrain may vary a little but it's basically a pinned throttle race.
ask the opti-dweebs how much use they got out of their gears.
they said the first six or almost half their rohloff was dead weight.
really, if there was ever a race tailor made for a hubbie, pikes peak is it.LI-ghtcycle wrote:Sure a hub motor properly modified/specialized for the specific task will be competitive, but if it's limited to the same weight, watt hours of battery and motor wattage, a properly sorted mid-drive type E-Bike is going to beat a hub motor every time. Sure in a Drag race or some similar event that might not be true, but in true endurance test like this event, efficiency & power delivery is going to trump a big motor every time.
never heard of the CSIRO solar car hubmotor?? (i think you have).
don't know what size mountains they tackled but regardless the motor can't tell if it's pushing against the wind or pushing against gravity makes no difference.
history has already proven you wrong that it's the hubmotor that can't be touched for efficiency.
actually you sound a lot like josh's friend who attempted the climb with him last year.
he wrote off hubmotors completely from his wild extrapolation based on a few meager data points.John Bidwell wrote:Learnings and take-aways are:
There is nothing like a derailer geared electric drive for efficiency on
steep hill climbs. All who made it were derailer geared, and all who didn't
well mr. bidwell, the stromer (a hubmotor) almost made it going 24 of the 26 miles falling short only for the want of miscalculating by a few amp-hours.
he had 720Wh compared to optibikes that came equipped with over 1 kWh packs.
not much of difference in energy consumed either way.
Hey there, kinda touched a sore spot did I?
Don't get me wrong, I have no hate for hub motors! They are by far the simplest and most cost effective E-Bike motors around!
They are also some of the least efficient around (while laced to a typical 26in/700c wheel, even a 20in isn't going to cut it at the same voltage/watt hours) , when in my own testing I used only 35% of what was required to power the same hub motor on the same bike doing the same hill climb when used as mid-drive with appropriate gearing VS wasting over 60% of my AH's in heat, I think you are missing the point.
I'm not saying that a hub motor can't hack this hill, I am saying a hub motor given the same power available (same amount of watt hours), being so much more wasteful in it's energy consumption is just going to loose.
It's like comparing a early 50's V-8 to a modern V-6 or even some 4 cyl engines, SURE you can do all kinds of mods on that old V-8 and get the performance you want, and use 4x the fuel, and what have you, but that's not saying it's even in the same class as a modern efficient engine with a turbo/supercharger.
The fastest E-Bike I've heard mentioned on this board so far has NOT been a hub motor, it has been a single stage reduced Agni motor with a TON of battery what was it ... 20 Kilowatts of power reaching speeds of 92 MPH?! Now take that same bike, give it the same battery powering the Optibike and see how far it goes up the hill at Pikes before it runs out of juice.
All things equal, efficiency wins the day. If you don't have restrictions on power (i.e. the year they let larger engines compete at the Indy 500 if they were PUSH-rod instead of OHC) sure lesser tech can win, but once you level the power used, unless you're doing a short burst of speed like in a drag race, the more efficient system will win every time.
Imagine two racers in TDF with equal strength and skill, one with a fixie, one with a standard geared bike. It really doesn't matter if the gear ratio on the fixie is a pretty good compromise between hill climbing & high speed flat-road gearing, the rider with more gears to use is always going to have a huge advantage.