I don't understand how to translate bike watts savings to a race. If I average 230 watts over 4.5 hours, say, without a "10 watt savings" what can I expect my average watts to be with said 10 watt savings (all other things being equal).

I don't understand how to translate bike watts savings to a race. If I average 230 watts over 4.5 hours, say, without a "10 watt savings" what can I expect my average watts to be with said 10 watt savings (all other things being equal).

230 Watts

230 Watts

If every single variable was the same, and you put on a bike addition or clothing adjustment that truly was "worth 10 free watts", then you could think of it two ways:

1. You could average 240 watts for a little less than 4.5 hours doing the same exact effort as before
2. You could average 230 watts over 4.5 hours with a slightly less effort

So in this case I think you would be #1. You want the same effort but you want to apply a 10 watts savings. I think you just take the 230 watts and add 10 to 240.

I could be wrong, but that is the general idea I think...

...I think

230 Watts

SteveJ is right... if you're saving 10 watts, you'll go 1sec/km faster at normal cycling speeds than if you weren't saving those watts. Over an Ironman, 10 watts is roughly 3 minutes at normal cycling speeds.

You're confusing things.
You need to state where you're measuring the power for this version to make any sense.

The general rule of thumb:

5 watts savings = 0.5 sec/km faster

Hello

let's take an example, with a rider of 75kg, CdA 0,22 average over the course, delivering 230w constantly. Flat course.

With some other hypothesis fixed (bike friction, tyre loss, road efficiency, air pressure, ....), average speed is 37.7 km/h.

On a 180km IM, this lead to 4,77h time (approx. 4h 46n12s).

If you go CdA 0,21 average through new helmet + position change + new wheel + ... whatever, all other hypothesis staying unchanged, you save 7 watts.

If you keep pushing 230w average, then speed goes up to 38.2 (not going to far in precision).

Gain is 0,5 km/h for 7 watt aero gain.

So, kind of 0,07 km/h per watt. This value change if wattage, CdA, or delta gain, or other parameters... change.

Over 180km, time go down to 4,71 ( approx. 4h 42mn 36s)

So IM gain is 3mn36s, for 7 watts.

Kind of 31s per watt gain for an IM.
So, 15,5s gain per watt for a 70.3, at this power/CdA/ + other hypothesis.

All this being non linear, this value per watt do not apply on a linear way, so can only be applied for limited gains (5 to 10 watts), with equivalent hypothesis.

Philippe

I don't know... I mean if I ride a max effort at 290 watts and a magical fairy turns back time and gives me 10 free watts, I feel like I could ride max effort at 300 watts.

...or ride a little bit below max effort at 290 watts again.


hmm....

This seems simple enough for me to understand. It seems like the description of whatever savings one gets in terms of watts should be based on some time/distance metric... like watts/hour something? Science and math are NOT my strong suit (obviously).

Wattage is your output. You aren't changing, you will put out 290w wearing a skin suit, you will put out 290w wearing jeans and a sweatshirt. It all matter what forces are you overcoming with those 290w. If you get "10 free watts", it's just taking fewer watts to overcome those forces, ergo you put out 280w to overcome them. The extra 10w (since you are a constant 290w) goes towards increased speed.

Your output doesn’t change. But the measurement of your output changes depending on where the measuring device is located.

If you gain 10w by reducing chain and pulley friction, then you won’t see any difference in your crank or pedal based PM, but your Powertap hub would read 10w higher.

Yes, this is kind of my point I think. To translate the marketing claims into something tangible is a bit convoluted. Unless that is just me and everyone else sees "5 watts per tire" and goes "Oh! I'll shave 2 minutes off of my Ironman bike at the same output!".

Yes, this is kind of my point I think. To translate the marketing claims into something tangible is a bit convoluted. Unless that is just me and everyone else sees "5 watts per tire" and goes "Oh! I'll shave 2 minutes off of my Ironman bike at the same output!"