Wheel Suckers

[DismalScientist]

Especially since poseurs are notoriously weak hill climbers.:rolleyes:

[Dickie]

@skins_brew 99314 wrote:

If you really want to see the impact of a draft get behind a SUV (or a large truck) at a stop sign. This isn’t the safest thing in the world, so it is best to do it in a quiet neighborhood, but such a vehicle can easily pull you at like 25 mph without much effort on your behalf.

[IMG]http://bikearlingtonforum.com/attachment.php?attachmentid=7005&stc=1[/IMG]

[dkel]

@DismalScientist 99340 wrote:

Especially since poseurs are notoriously weak hill climbers.:rolleyes:

Boy, is this ever true! And one of the problems with hills is that once you get up one side, you often go right down the other. I can’t tell you how many times I’ve gone by people on the uphill only to have them fly by me on the downhill (and going fast downhill is no accomplishment). Then we’re right back where we started, with me aggravated, and them feeling unjustifiably smug.

(Thanks for listening! :o)

[Terpfan]

@DismalScientist 99340 wrote:

Especially since poseurs are notoriously weak hill climbers.:rolleyes:

By hill, you mean even anthill. I swear it’s once a week someone passes me on MVT south going home and then as soon as there is any remote climbing (even those puny ant-like hills by the airport), I go flying by them.

[mstone]

@dkel 99384 wrote:

I can’t tell you how many times I’ve gone by people on the uphill only to have them fly by me on the downhill (and going fast downhill is no accomplishment). Then we’re right back where we started, with me aggravated, and them feeling unjustifiably smug.

Somebody is sounding pretty jealous of the heavy! I earned that downhill F (= ma)!

[DismalScientist]

Yes, dkel and I often worry about being blown away in a slight breeze.:rolleyes:

[dkel]

@mstone 99395 wrote:

Somebody is sounding pretty jealous of the heavy! I earned that downhill F (= ma)!

Weight doesn’t translate into speed going downhill; Galileo demonstrated that at the Leaning tower of Pisa.

[rcannon100]

I challenge anyone on the forum to a downhill coast. Galileo was a dork and I can prove it!

(What was that u wear saying about “science” KelOnWheels????)

[mstone]

@dkel 99414 wrote:

Weight doesn’t translate into speed going downhill; Galileo demonstrated that at the Leaning tower of Pisa.

That’s true, in a vacuum. Try throwing a brick and a feather out a window and report back.

More geekily: assuming similar aerodynamics, the heavier rider will have a higher terminal velocity because the two riders will experience the same drag (which is not dependent on mass) but different forces from the acceleration downhill (directly dependent on mass). The terminal velocity is reached when the drag force equals the acceleration force. (In a vacuum the velocity is the product of acceleration and time, and is not dependent on mass.)

[AFHokie]

@mstone 99419 wrote:

That’s true, in a vacuum. Try throwing a brick and a feather out a window and report back

Please clear the impact area before throwing…feathers can tickle

[Vicegrip]

@dkel 99414 wrote:

Weight doesn’t translate into speed going downhill; Galileo demonstrated that at the Leaning tower of Pisa.

Galileo did not ride a bike.

[mstone]

@Vicegrip 99437 wrote:

Galileo did not ride a bike.

Loser!

[dkel]

@mstone 99419 wrote:

That’s true, in a vacuum. Try throwing a brick and a feather out a window and report back.

More geekily: assuming similar aerodynamics, the heavier rider will have a higher terminal velocity because the two riders will experience the same drag (which is not dependent on mass) but different forces from the acceleration downhill (directly dependent on mass). The terminal velocity is reached when the drag force equals the acceleration force. (In a vacuum the velocity is the product of acceleration and time, and is not dependent on mass.)

In the case of cyclists, the difference in mass isn’t great enough for the brick and feather analogy to apply, and I haven’t yet met a cyclist that can achieve terminal velocity. Galileo and I are still right. A more relevant consideration might be momentum, which would carry the heavier cyclist at speed for longer. The only thing I can think that matters to this scenario is that the more massive cyclist might overcome rolling resistance and drag more easily, but I imagine that effect is negligible.

[hozn]

What do the maths actually say? I know there is a commonly held belief that heavy does make descents faster and this seems to bear out with extremely unscientific anecdotal experience — just comparing descent speeds with other cyclists.

I also attributed any difference to mass and frontal area relationships, but I never sat down with a calculator to see what the real effect would be. Wind resistance (at downhill speeds) is a powerful thing. Seems much more significant than (overcoming) rolling resistance here.

Either way, though, I rest confident that I can make up much more time on a climb than I would lose on the subsequent descent.

[dkel]

@hozn 99445 wrote:

Either way, though, I rest confident that I can make up much more time on a climb than I would lose on the subsequent descent.

This is really the only point I’m concerned with. I learned early on in my adventures cycling that the way to improve my average speed over my commute (or any ride) is to climb faster. As a result, I don’t feel like putting in a lot of effort attacking the descents, and I don’t appreciate Cat 6 poseurs who make all their moves on the downhills. Pass me on a climb and you’ve earned my respect (I say this as someone who is not brilliant at climbs, but as someone who rides enough not to suck at them, and as someone who rides enough to recognize someone who does suck at them, even if they don’t think they do).

I bet Galileo would have kicked ass as a cyclist, because he would have used his brain to go faster; he would never have been a poseur.

[Author]

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