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-   -   physics of drafting busses (https://www.bikeforums.net/commuting/97805-physics-drafting-busses.html)

JavaMan 04-07-05 08:53 PM


Originally Posted by TrevorInSoCal
Don't be so sure. My personal best is 173 RPM (36 MPH on a fixie w/ a 42x16 gear). Though I can't claim to have been exerting any actual power to the pedals at that point. It was all I could do to *keep up* with them. ;).

On a bike with a freewheel though, you could probably manage short bursts of a super-fast cadence to just *barely* maintain enough speed to stay in the draft...

-Trevor

Did I mention I have 180 mm cranks? For me (37" inseam) I think it would be impossible. However, since my new computer can display cadence, I will certainly try. Thanks for the inspiration!

slvoid 04-07-05 08:59 PM


Originally Posted by CdCf
Drag is a force, yes, but we don't really have to worry about force when we ride.
That's what gearing is for.

The last time I checked, when the wind pushes against you, it's a force. I'm glad you don't have to worry about this opposing force but the rest of us who live in reality will unfortunately have to deal with the opposing force of air pushing against us every time we ride.
There is a difference between the force you put down on your pedals and the force of the air pushing against you. You've confused the two. One you would use gearing to overcome, the other.. other than getting more aerodynamic, I'm not sure if there are any other ways to overcome wind resistance.

DogBoy 04-07-05 09:17 PM


Originally Posted by slovid
...I'm not sure if there are any other ways to overcome wind resistance.

Ride your bike on the moon?

slvoid 04-07-05 09:31 PM


Originally Posted by DogBoy
Ride your bike on the moon?

Apparently I'm wrong... I stand corrected.

operator 04-07-05 10:10 PM


Originally Posted by slvoid
Apparently I'm wrong... I stand corrected.

You could also cycle underwater.

vrkelley 04-07-05 10:55 PM


Originally Posted by genec
Also bear in mind that Dave or any other drafter is not having to break wind

Well they could've been brek'n the wind...I wasn't there :p

CdCf 04-07-05 11:31 PM


Originally Posted by slvoid
The last time I checked, when the wind pushes against you, it's a force. I'm glad you don't have to worry about this opposing force but the rest of us who live in reality will unfortunately have to deal with the opposing force of air pushing against us every time we ride.
There is a difference between the force you put down on your pedals and the force of the air pushing against you. You've confused the two. One you would use gearing to overcome, the other.. other than getting more aerodynamic, I'm not sure if there are any other ways to overcome wind resistance.

Yes, it's a force, but you don't run out of force in your legs, you run out of power (provided you have sufficient gearing), so force isn't as interesting as power here.
Of course, the drag force is "two thirds" of the power, so it's important for sure, but it's not really what we fight against when we pedal. Our effort pedalling is the power required, but the force we're pushing down the pedals with depends mostly on gearing, and is limited at the lower end by the cadence we're comfortable with.


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