Wheel Suckers

[mstone]

@dkel 99440 wrote:

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.

So on all your downhills your speed increases infinitely? Mine usually increases to a point and then maxes out at the terminal velocity. (Note that this is not the same terminal velocity you’d achieve jumping out of a plane because on the slope you only get a fraction of the acceleration of gravity.)

[dkel]

@mstone 99448 wrote:

So on all your downhills your speed increases infinitely? Mine usually increases to a point and then maxes out at the terminal velocity. (Note that this is not the same terminal velocity you’d achieve jumping out of a plane because on the slope you only get a fraction of the acceleration of gravity.)

We’re not talking about coasting. I don’t know what speed a bike would have to go to achieve terminal velocity as you define it, but I have yet to find a case where I feel like I can’t pedal harder and increase my speed. For me, fear takes over long before my ability to push harder fails. One of the few deaths in the Tour de France occurred when one of the riders lost control on a descent–at 55 mph. Really, any time energy is applied to increase velocity, terminal velocity becomes irrelevant; if not, no vehicle would ever exceed terminal velocity, and there would never be any breaking of the sound barrier, for example, or achieving escape velocity.

[dkel]

Now that I think about it, I’m sure there is a terminal velocity for bikes: even though bikes are darned efficient at converting human power into motion, there is a limit as to how much energy is available to a human and how well the bike can translate that energy into motion. I just don’t think I’ve reached it yet, nor would I feel safe doing so. Also, I don’t think it would really come into play on most descents in most Cat 6 racing.

Also, I get your point, mstone, about gravity on a slope. To split hairs, you do get the full acceleration of gravity, but when on a slope, it is applied over a horizontal distance in addition to the vertical distance.

[hozn]

@dkel 99450 wrote:

We’re not talking about coasting. I don’t know what speed a bike would have to go to achieve terminal velocity as you define it, but I have yet to find a case where I feel like I can’t pedal harder and increase my speed.

Ah, I assumed we were talking about coasting. Or, more specifically, the fact that heavier riders can coast faster, while lighter riders have to start pedaling to keep up.

But sure, if you have the gearing, you can pedal into the 40+mph range, which is where I tend to start looking to slow down on normal-road descents. I do recognize that descending is a skill, which I suck at, though. It takes a good understanding of traction & braking, good focus etc. — as well as the ability to take risks — to descend at race speeds.

I too value/pursue the physical fitness needed to climb fast more than the skills needed to descend fast, but either way I am sure that flying down rollers on the Custis is just dumb. Especially if you are doing this for the cat 6 points competition.

[mstone]

I’m certainly talking about coasting. Usually when I pass people on a downhill it’s because I don’t feel like braking, not because I’m pedaling. Why would I ruin a perfectly good bike ride by trying to turn it into a race?

[DismalScientist]

My terminal velocity is determined by brake rub.

[dbb]

@mstone 99419 wrote:

That’s true, in a vacuum.

I tried that once and found myself breathing way too hard:o

[dkel]

@mstone 99455 wrote:

I’m certainly talking about coasting. Usually when I pass people on a downhill it’s because I don’t feel like braking, not because I’m pedaling. Why would I ruin a perfectly good bike ride by trying to turn it into a race?

Right! I did bring up Galileo, so I guess coasting was implied. I was hung up on those turkeys that race down hills though. All I all, I’d say the physics of descents is pretty complex, what with the various acceleration and resistance factors working against each other.

[Tim Kelley]

@rcannon100 99417 wrote:

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????)

Challenge accepted. Not too many people around here are as heavy or as aero as me…

[skins_brew]

@Dickie 99344 wrote:

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

Now this is hardcore drafting!

[Orestes Munn]

How about a little pig lead in the bilge? That’s how we sometimes even things up in sailboat racing.

[Drewdane]

@dkel 99384 wrote:

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)

Speaking strictly for myself, that behavior has nothing to do with my ego or any desire to compete with you or “accomplish” something. It’s just that my, er, “custom-built personalized waist-mounted bioform gravity assist belt” has that effect on my riding patterns. :rolleyes:

[ATTACH=CONFIG]7010[/ATTACH]

[mstone]

@dbb 99458 wrote:

I tried that once and found myself breathing way too hard:o

At least nobody had to listen to you!

[dbb]

@Tim Kelley 99478 wrote:

Challenge accepted. Not too many people around here are as heavy or as aero as me…

Tim – Let’s split the challenge and put some money on it. A buck a pound on the heavy part of the challenge?

[Tim Kelley]

@dbb 99492 wrote:

Tim – Let’s split the challenge and put some money on it. A buck a pound on the heavy part of the challenge?

Can I wear my time trial helmet?

[Author]

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