Thanks for the debate.
The thread is showing 760 views and 33 comments. Generally I can expect a comment per thousand readers so this is an extraordinary response. However, only 70 people thus far clicked across to the original article at http://blog.urremote.com/2012/12/what-w ... -when.html
, a bit less than 1 in 10 thread readers. That suggests some comments are a reaction to other comments rather than the initial argument which was along the lines that with a little bit of assist you could win the Tour de France but with 500 W you'd have a dissatisfying motorbike. NeilP spoke for many:-
YES YES YES YES YES!!!
Ken Taylor wrote:Do experienced ebike riders always get more satisfaction from more power?
and some like:-
maydaverave wrote:I have a low power 1000 watt bike. Its a great commuter for my small town and as time goes by I find myself going slower on it.
had a different definition of low power than I'd intended.
Kraeuterbutter at http://endless-sphere.com/forums/viewto ... 85#p587951
is somewhat sceptical of the power requirements of Endless Sphere aficionados.
However, there was some with plenty of experience of high power bikes who saw merit in low power bikes which I'd define as not more than 2-3 times more power than pedalling. For example:-
chvidgov.bc.ca wrote:I've experienced this when I recently put a "Cute" motor on a nice light aluminum framed roadbike.... I've been very happy with the very bikelike experience
Jeremy Harris wrote:I started out with a fair bit of power, but find that the ebike I like best, and ride most, is the light one with the low power motor. The reasons aren't that straightforward, I think.
....That article does have merit. A bike w/motor takes the physicality of the experience away. I'm really hesitant to taint my last true bike into a motorized vehicle.
Some commented on the psychology of power:-
dogman wrote:A great deal depends on the goals of your ride. As goals change, the mental attitude changes.
rocwandrer having never ridden an e-bike felt unqualified to add to the discussion but pointed out that:-
rocwandrer wrote: The vast majority of my riding time is purely recreational, with the destination being the departure point.
which is probably pretty common and my favourite version of cycling. After presenting the reasons he claims:-
If the benefit from adding pedal power does not FEEL proportionate to the effort, it is much harder to put in that effort....That all matches with Ken's hypothesis that if there is enough power on tap with the electric assist to make the human contribution feel less critical, or to make the return for extra effort feel too small, it is will psychologically difficult to even acknowledge that there is more in reserve in the human power side's controller.
Following a link provided by rocwandrer led to John Tetz's graph on the physiology of power.
So with the benefit of all that input I can refine the original hypothesis:-
1. Uncontroversially - lightweight is always better.
2. Engineering, psychology and physiology all have to be optimised for satisfying electric bikes.
3. Like in robotics, electric assist on bicycles suffers an uncanny valley
. A small amount feels good and the rider always wants more but at some point the criteria for satisfaction shifts so as that as the rider descends into the valley, despite desiring more,increased power reduces satisfaction. As power increases further the rider climbs the far side of the valley and more power again increases satisfaction until the desire is finally satiated at multiple kilowatts.
If there is merit in the hypothesis it follows that giving a rider more power on demand isn't always going to provide the most satisfaction. On the left side of the valley you might do better by reducing rider control. Some possibilities are:-
1. Run the motor at the point of maximum efficiency for whatever speed the bike is travelling and rely on the rider to add sufficient power to maintain speed. This would increase range for a particular battery size.
2. Hill flattening. Sense the grade and provide power to offset a portion of the riders weight on hills. If the portion was 100% a hill would feel no different to the flat. Especially good for people that are overweight.
3. Don't provide assist until the rider is putting in more effort than it takes to walk then add more as the rider adds more. This might encourage the rider to increase their effort rather than reduce it. Most of the assist would be spent overcoming air drag in this case which is non optimal for range.
4. Use heart rate as a sensor input. If the rider is not working at 80% of maximum they don't get any help but the more they go up the more help they get.
5. Don't provide much assist at the start of a ride but add assist as the time goes by in the proportion that the rider tires.
6. Vary the algorithm depending on the purpose, for example a ride for pleasure and exercise versus a desire to arrive at the office sweat free.
A good algorithm would be one that encouraged the rider to exercise more rather than motivating them to minimise effort.
Pursue minimalism, then remove weight.