Originally Posted by
woodcraft
Huh.
So if the patch is about .75" it would be about 1/112 of the wheel circumference and about 1/4 of the tube circumference.
The thickness of a patch is similar to the difference in thickness between a standard tube, and a lighter tube.
The difference in rolling resistance between those tubes is about 1 watt for pair of tires at 45kph,
so a patch could theoretically require about .0022 watts at 45kph.
https://www.aero-coach.co.uk/inner-t...ing-resistance
Then, if I have the math right, they suggest a 4 second difference in a 40k TT for 1 watt of RR,
so a tube patch could cost you .0088 of a second over a 40k time trial at 45kph.
Presumably, the increase in rolling resistance is because thicker tubes are stiffer overall.
The effect of the very small area of the patch is probably lower than the simple linear scaling you are using. So, your estimate might be a large exaggeration.
If his tires don't have low rolling resistance, it's odd to worry about the tiny effect the patch is likely to have.
In any case, it doesn't seem the OP should be spending any time worrying about 0.0088 of a second.