Roger_H wrote:(I ask the latter Q because of suggestions that the average rider turns out 250W in some posts. Now in my racing days - many years ago - my sustained power out put would have been higher - but I suspect 250W would return a lot of riders a 50 mile time between 2 hours and 2 hours 10, if not using pointy helmets etc.
A lot of us are now a lot lower on power output, which is why we are considering e-bikes . . . but Yates is a good example - someone who likes to ride his bike but, for medical reasons, probably now has a power output more in the 100W range.
My interest in this thread was prompted by MrsH saying that she would like to try an ebike. We even have what I think is an excellent recipient bike for a front wheel kit. However, I find it hard to grasp what she might gain that she wouldn't from some sustained build-up of fitness. Even round here in hilly Cornwall, the hills aren't impossible and the fitness gain even greater. As her power-to-weight ratio improved, I reckon the hills would start to disappear; she isn't overweight (60 kg) and has no physical impediment but if you don't cycle regularly in Cornwall it's easy for the gradients to start to loom larger. I am beginning to think it is (a) a mental thing (b) a fear/dislike of the discomfort of going through the building up of fitness and (c) a lack of belief that it is actually possible to be that fit. An ebike therefore would be like a security blanket (for an otherwise fit/healthy person). By the way, I am not talking about regular long commuting here in which an ebike plays a different role.
I would love to be able to measure her power output (and mine) and see just how far off she is from needed any e-assist.
I don't think it's that hard to measure power output, particularly on hills. If you install Strava on a phone and run it it will give you numbers.
In particular your weight and your bike weight are plugged in.
I think I have told it I am 85kg with a 9kg road bike and it tells me that over a 15 minute 4%/4km climb in the middle of a 4 hour ride I am averaging 213W.
If I try very hard I can get up to around 300w for say 5 minutes and for a short burst of a minute or so 400w.
I think the power meter people use a number they call 'functional threshold power' which is supposed to be 'all-out effort for an hour', though it's measured over a shorter timeframe because if you are putting out say 200W up a hill for 15 minutes you'll probably then go down it freewheeling just because of terrain. So it's a bit hard to measure.
Anyway I'm not sure how useful their numbers are in that if I am in practice putting out a bit over 200W up the longest sort of hill I encounter regularly then that seems a good number to use.
So if I take that over herehttps://www.gribble.org/cycling/power_v_speed.html
And lets keep the power at 200w and ignore the various other numbers because it's uphill so they aren't that important (ok I upped drivetrain losses to 5%)
And if we have a hill of 7% then that is about 9.7kph/6mph
If we take that here http://www.bikecalc.com/gear_speed
Then with a 50/34 and an 11-28 at 60rpm it goes down to 9.1kph
So in other words I can pedal in my lowest gear and easy cadence for a sustained hill of up to about 7%.
A long 10% hill and I'd be in trouble though I could manage the 300W for say 5 minutes. For extremely steep, say 20% then I need 400w to do only 7.4kph, which is 50rpm so possible but just briefly.
If I put out my 200W up the Hardknott Pass which is average 13.3% then that gives just 5.4kph. With 50/34 and an 11-34 that would be around 43rpm, so no thanks. But with a Shimano 'trekking' triple of 48/36/26 and an 11-36 you'd be right there in bottom gear at 60rpm.
As far as power to weight goes more generally, lets say I'm 85kg and I'm producing 300w for 5 minutes. That is 3.5W/kg. If I went to 70kg it would be 4.3W/kg.
However as we can see here there is a 21% power/weight ratio for men over women:
So my 4.3W/kg as a lean 70kg would as a lean woman be only 3.5W/kg.
And then comparing total system weight:
Me + bike =95kg and 300w or 3.2W/kg
60kg woman of same relative W/kg power (relative to the average woman) + 10kg bike producing 60 * 3.5 = 210W that is then 3W/kg for the system
So even though I'm 15kg overweight and we both hypothetically have the same relative level of fitness, I still have an almost 10% advantage because of my sex and also because the weight of the bike becomes less significant when the rider is bigger.
(Note obviously that the more you weigh to start with the less it matters the weight of your bike, and equally the more gear you should carry when touring relative to your partner. )
So as far as your fitness versus your wife's assuming you are both the same age and not overweight then you have about a 20% advantage in power and assuming you are taller than she is, as most men are, then you have a further boost again as greater total power cancels put bike weight.
I suppose if you wanted to try and equalise things then you can either add an electric motor, which would completely overcome any shortcomings in that as per the example above you have let's say 200W vs. 133W but then add on a 250W (actually more in many cases) then you now have DOUBLE the total power. And the extra weight of the e bike is likely not relevant as the system weight of you and bike Vs wife and bike would likely be similar so you just have double the power on the e bike side.
As far as matching the e bike's performance with training goes, it's impossible. What you could do is establish current power levels and figure out what the difference is and perhaps put some lead weights on your bike to compensate