Originally Posted by
gregf83
Why is it a useless measurement? It correlates very well to your power/weight ratio.
well, the reason why i see it as useless is because of the wide open interpretation, at least that is how i read the thread opener. the units are meters per hour. i can always ride a steep short hill and use maximum power. compare that with an equally steep but much longer hill i highly doubt my mph will be the same. my local favorite is about 8 miles long. i ride this all the time, i am faster at the bottom than at the top and the grade does not vary by too much. i'm pretty sure that if i did the calculations my mph would steadily decline as i went up that hill, i simply get tired the longer i ride.
if the measurement were described as something like "VAM is a measurement of meters per hour taken under the following conditions: x% average grade with a variance of +/- y% ridden for a total of z minutes" then i would find VAM a useful measurement. this puts everyone on the same page, kind of like my car can go from 0 to 60 in xyz seconds.
i drive an older model CRV by the way, probably in the 15 second range on a good day, down hill.
-scott
i might want to add the riders current elevation. i live in reno NV. not much air up here compared to our friends in FL.