Originally Posted by
xenologer
Note: imi is the OP
When a thread goes 7pages, sometimes it's best to just focus on the first post...
"All conditions being equal" versus "extra girth" are a contradiction, since girth is going to effect air resistance; and I think you are primarily interested in the weight issue right? Please clarify exactly what you meant by this so we can clear up some of the confusion and arguments.
May I suggest modifying the original query to put both riders in recumbents with full aeroshells big enough to hold the larger of the two?
Uhh yeah... I'm not touching this point till the OP clears up some of the hypothetical setup to remove ambiguity.
Hi, I'm the OP
Thanks for the bounce back xenologer...
What I meant with "all things being equal" was that the only difference between the riders was that one was twice the others weight and would thus also have a greater cross section (bigger guy, I called this girth), but that they were on exactly the same bike, same tire pressure, riding in the same position (say fairly upright), on the same hill, no wind, etc etc...
From your answers (sorry I can't follow the math) would I be correct in concluding that:
1. The heavier rider's extra mass causes him to accelerate faster down the hill solely due to the effect of gravity in an atmosphere?
2. That his assumed larger cross section (which I called girth) would slow him down due to greater air resistance?
3. That his tires have a greater contact area with the road thus increasing friction (heat) thus slowing him down?
4. That the air resistance and friction, however, are less than his greater gravitational acceleration meaning that he would get to the bottom of the hill first?
To the other part of my question... Assume there is another hill after the first, the guys are still coasting, would the lighter guy catch up on the way up the hill or come to a stop further up the hill than the heavier guy (or the other way round)?
Hope this clarifies my question
Thank you for your time and knowledge