rustguard wrote:Marlin 3030 wrote:This is seriously cool. Shame it exceeds Australian standards
yeah 500watts and it has a top speed of 20mph which I think is 31kms.
you start to see how ridiculous(devious) the 200watt limit really is
The RTA's draft papers are suggesting a 250 watt limit. There's not much that's devious or ridiculous about it if you read the full story in their papers.
The bike pictured by Marlin 3030 is giving a rating per the American and Canadian regulations. 20 mph is 32 kph (or 32.18 if you want to be fussier).
The Canadian and American definitions mention a speed of 32km/h. This is not a maximum
assisted speed, but rather an indication of the speed achievable on motor power only. In Canada,
the British Columbia Motor Vehicle Act states: ‘The motor of a motor assisted cycle must … not
be capable of propelling the motor assisted cycle at a speed greater than 32km/h on level
ground.’
The 32 km/h speed limit, as described by the Canadian and American Regulations, cannot be seen
as effectively limiting the speed achievable with motor assistance, because at speeds above 32
km/h, the motor can still assist the rider.
The RTA have very sensibly looked at the potential total power output and speeds that are achievable for a rider who is providing pedal assistance. The Canadian regs say that 500W is the level that a well-trained athlete can maintain for a short period of time. How short ?
NASA tested various categories of people. Someone in their "healthy men" category could maintain 250W for about 30 minutes; Eddy Mercyx could maintain it for over 12 hours (i.e. until sleep required). A NASA "first class athelete" could maintain 500W for around 3 minutes. Eddy Mercyx could maintain 500W for about 40 minutes on an ergometer. A "healthy man" could do 500W for less than 1 minute. There aren't too many people out there who can commute to work at an average power output of 500W, or even at 250W.
With 500W motor assistance, plus 250 W pedalling from the cyclist, the Canadian e-bike would be pretty easily rolling along on the flat at over 37 kph. They would be significantly faster than the elite cyclist producing 500W, and well over the speed measured in the Monash study for average cyclists.
Potentially there could be a lot more 500W bicycle riders than we have elite cyclists out there - and that would present a very adverse shift in the risks to vulnerable road users.
A 250W motor assistance gives an average fit person almost the same performance capability (total 450W) as the elite cyclist (500W), but in a way that's sustainable over a much longer period. The delightful Mr Scruby would most likely take issue with dangers this could present if lots of people took up 250 W pedal assisted bikes. So we should be thankful for small mercies if lifting to 250W from 200W does get up.
Objectively, there's not too much to be disappointed with in a bicycle that can move you along on the flat at 32 kph unassisted. That's quite a respectable speed compared to average motor vehicle speeds on Sydney roads.
Edit: 5/5/2010:
The NASA power measurements seem to understate the speed for a given power. Twizzle has reported in this thread than he can average 39 kph with 374 W of power over 20 minutes. 500W could obviously get him moving quite faster - maybe 42 to 45 kph, and clearly for much longer.
I'm not exactly unfit, I normally average 30kph+ on my commutes but I am lazy and I do like the benefit of getting to my destination in regular clothes and not sweaty. After living in Holland as a child I do see cycling as something you don't need to sweat for.
