Power question

BeauMaximus

Last week I rode with a guy who's PM shows his avg power for the 3:15 ride.
I'm about 7kg heavier and (due to my good wheel currently being repaired) was riding a £45 rear wheel with shot bearings compared to a £1k rear wheel.
Does the weight/wheel difference automatically mean I must have been pushing more power than him to keep tje same speed over the duration or is it more complicated than that?
Now I did bonk near the end so we had to cruise the last 1/2 hour at my speed, but I don't think that has a bearing on my basic question.

Thanks

jibberjim

Way more complicated...

Even with shot bearings, aerodynamics will dominate on a ride, so your positions and which one of you takes the wind will decide, not the state of your wheels or weight.

Chebrikov

Without knowing CdA it is impossible to be sure, however, all things being equal the heavier rider will need more power. Also the heavier rider will probably have a higher CdA so need even more power to overcome drag. So assuming rider position is similar and both spent the same amount of time on the front the bigger rider probably needed more average power.

At 20 mph, 7 kilos costs 6 watts approx per 1% gradient. Even terrible bearings will only cost a watt or two. The heavier rider will need more watts to overcome rolling resistance and friction but this would only be another 2 watts or so. The heavier rider needs more power to get up to speed.

It is though, possible that the smaller rider has a less aero position on the bike, less aero clothing and wheels etc so you can't be sure. Do not underestimate the cost in watts of extra weight which is always there, very few roads are really flat anyway and weight does still cost you some power even on the flat although on the flat at TT speeds aerodynamics is going to be the prime concern..

GiantMike

What was the other guy's power for the ride?

Further to the replies above, there's more to power than just average power. Average power just wraps up a load of little episodes on the whole ride into a single number. Lets say he put put 200W for the ride. You'll be putting out about the same (assuming it's a flat loop and you shared the work equally), or probably slightly more if it was hillier. However, the way you deliver that power over the ride may vary enormously. You could ride 240W steady, or something like 300W/100W alternating each minute. The te former would be quite easy and the latter would be a much harder ride.

BeauMaximus

Thanks for the replies,

his was 240 avg power, (or 259 weighted avg power but not sure if this is just something strava calculates)
In this case, he was definitely doing more work toward the end but I was just asking a general question to understand how it works.

He also definitely rides a constant hard pace which is what killed me!
My energy seems to ebb and flow, I can blast up short hills quicker but seem to struggle with a long steady hard pace, no recovery I suppose.