I am curious about undertaking aero testing by doing rolldowns of a hill and measuring speed. point is not to say it’s better than wind tunnel or chung testing…but if i wanted an attainable way to tease out qualitative (i.e., NOT quantitative) differences between variables, is this reasonable/worth my time? i searched for other threads couldn’t find any. sorry if i missed.
I have a no traffic, straight, smooth pavement hill near me. averages -6.1% but is steeper at bottom so speeds get higher. takes about 1 minute down, clocked it today from a standing still no pedaling rolldown, i get to 42 mph at the bottom. hill is short enough that i could do many repetitions during one session, and there’s a parking area right at the bottom so i can easily bring supplies/make setup tweaks right there. I’d use a wheel speed sensor, start exact same point from standing, no pedaling, and measure max speed at a known point at the bottom (there’s a driveway i can use as fixed speedcheck point). i’d do it the same way as wind tunnel testing, only change one variable between comparison runs/sets. compare max speed at that fixed point of all runs and see if can see any differences/trends. obv like chung testing would pick a day with no wind, etc.
at very least, feel like it could give me reasonable confidence with setup decisions and whether A or B is likely faster. the only downside I can see is that it would not give me any wattage or cda measurables as to how much faster/slower, and it’s just a plain yes or no answer, but 100% i can live with that given how easy and repeatable this testing could be for me.
thoughts? tips?