FWIW, the "rule of thumb" is a pretty good approximation for the range of average speeds that riders will see (say 18-28mph). This is true for the very reason you cite: going slower means you are on the course longer and thus you have more time to experience said aero benefits.

You can think of it this way to help, translate it to money. At X drag, you save no money. At x-100, you save 5 cents for every 30 minutes you're on the course. At 30 mph, you'd complete an IM course in 3 hours, 44 minutes. In that time, you'd save 35.70ish cents. At 20 mph you're on the course for 5 hours, 36 minutes, so you'd save 55.3ish cents. You save more at the slower speeds simply because you are out there longer. You're still saving at the same rate as someone going faster, they just have less time to bank.

John

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Top notch coaching: Francois and Accelerate3 | Follow on Twitter: LifetimeAthlete |

Great example; but, just to clarify, I don't see why people make the point of "saving more time the longer I'm out there."

That just means you're going slower, which the exact opposite of what you should be trying to do.

We aren't just moving our bodies for the convenience, we're trying to get there the fastest way possible. I think people kind of... translate that whole thing into efficiency, like driving 60mph over 75mph in hopes of saving 10 bucks of gas.

I don't remember what page I saw this on, but they touted the fact that you'd save more time the longer you were out there, and I also see people pushing this as a quality that people should take note of and whatnot.

Anyway, I'm just riffing here.

You are comparing a fast rider to a slow rider when the people who make this claim are comparing a slow rider to that same slow rider but with race wheels. Overall, the longer you are out there it is actually true that you save more time.

I think it's more that people see something like "At 25 mph you'll save X seconds", and they think "Well, but I'm only going 18 mph, how much time will I save?", and try to make that logic leap that that they will save more time because they are slower. Yeah, you'll save more time but it'll cost you more time to do it. :)

John

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Top notch coaching: Francois and Accelerate3 | Follow on Twitter: LifetimeAthlete |

The point of such information is to make people realise that sustainable aerodynamic improvements save everyone time, no matter how fast or slow they are to begin with. Aero works for everyone, there is no magic speed at which it kicks in.

Of course much slower riders likely have several areas in which they can improve their performance by some margin, but it's not an either/or game. It's possible to get fitter, lose weight, improve power and endurance, pace better, work on nutrition and improve aerodynamics. And have fun doing so.

Just accept that 50g drag@30mph saves you *about* .5 sec per kilometer on a flat, non technical course, no matter who you are.

That is all you need to know to make reasonable cost/benefit analysis.

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

Guys. I understand the logic.

But you're still going 18mph.

The goal in the race is to be fastest. What they're doing is some extra math to show you something that is VALID but is also NOT HELPFUL TO KNOW.

They might as well calculate calories saved and convert that to CO2 emissions and show you how green you're being.

Again, we all understand the math, but it doesn't help you to be more aerodynamic over time if you're going slower than everybody else. It's a race. So yea, you can save 10 minutes worth of time, but if you still come in dead last there's no logical point in it.

I'm just confused as to why this metric keeps coming up. I think people are, and I said this above, attributing it to being more efficient. Which is great, but you don't cross a finish line and worry about how much MORE time you saved on a course vs somebody who BEAT YOU.

It is useful to know because some people believe that they should not bother with, say, a disc cover, because they are slow.

Slow does not always mean you aren't going to win either. It might mean you are a competitive 60-65 female ironman. Such a person should understand that a disc cover is going to affect her podium chances the same (to close approximation) as ~23mph man or whatever.

The rule of thumb lets you napkin math whether you should get an aero helmet or a new front wheel, or a new frame or stick with your old one, and so on.

Nobody is going out and riding slower than they can to 'save more time'. I'm not sure what your angle is there.

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

So great. Get a 1980's colnago and go to town.

People care because if they don't save the drag through aero, then they are just that bit slower for the same effort. Someone that can hold 18 mph on a road bike might be able to hold 20 with all the aero benefits. But who cares, right?

John

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Top notch coaching: Francois and Accelerate3 | Follow on Twitter: LifetimeAthlete |

So I don't know if I'm being trolled... but...

Ok.

The goal of the race is to "win". Obviously.

The goal of all aero equipment is to
a) be faster
b) be the same speed but less power
c) be more efficient

The stuff works better at higher speeds.

When people want aero stuff, they want the stuff that saves the most wattage at a given speed. It would be "ok" to assume that this "most aero stuff" will be the best at all speeds.

Below is where people get confused.

YES: Riding your bike for a longer time will save you MORE wattage. This is simply due to the wattage savings being over a longer time.

BUT

Riding your bike for a longer time means you're riding the same course slower than your opponent.

So my wheel can save me 3 more minutes than you ALL ELSE EQUAL.

My wheel saved me MORE WATTAGE.

But I still finished 3 MINUTES AFTER YOU.

Because I was slower overall.

It doesn't MATTER that the wheel saved me 3 minutes of EXTRA time because this is a RACE. Not a standard road ride.

I'm just stating that it's a useless metric to have. No DUH you save extra time, you're riding the bike longer.

Again, it's just extra math that doesn't help you DO ANYTHING. You can't do anything with that value.

Again, it's like a driver finishing a race and ranting about how much gas he has left in the tank. Sure you can calculate that but who cares? That isn't a valuable metric to have.

There's no value in that metric.

That's all. Now if somebody can show me otherwise, I'll eat my hat. But, again, it doesn't matter.

But let's play; lets say you're looking at saving energy after the leg of the bike race for the run. Yes, staying on the bike longer will save you more wattage, but you're still behind all the other runners who pushed 25mph the whole time, while you pushed 22 and SAVED x number extra watts.

But that's not a metric that you can use in a race, because you can't just calculate your expected output from the get-go. you aren't a machine. it isn't an exact finite in = finite out. And that's where the use of the metric falls apart.

Compounding, even if you know your "immediate wattage saved since you stayed out on the course" number, you'll lose all of that in extra wattage running faster to catch the guys being initially quicker on the bike.

Perhaps they're not racing everyone else. Maybe they're trying to improve their time from the last time they participated in the same event. There can be some satisfaction in just trying to improve not necessarily in comparison to others.

Rasker4, you've actually asked a really good question.

So you already know the rule of thumb for aero gains. Now if you're slower, you will save more time, because you happen to be out on the bike course longer in the first place. Aero gains are also for slower people, like me.

Aero gains are roughly proportional to time on the course.

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AndyF
bike geek

For some, the idea is to be the best they can be. If you're in the 70-75 age-group, that will mean something different than if you're in the 20-25 age-group, don't you think?


Everyone justifies their races according to their own needs. Not everyone can set a course record for the bike leg of Kona. But somehow, IM seems to satisfy all these different needs very well.

Have you set any course records lately? ;-)

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AndyF
bike geek

My goodness.

It's like people can't wrap their heads around a bit of logic here.

It's fine; let's drop it. People having the number doesn't hurt anything; let's let them have it.

This is quite amazing though, I must say.

I wish that you, Slowtwitch, and the internet stay around long enough that you will still be racing when you're 70. You might understand a different perspective, or "logic", as you put it. In the meantime, I also sincerely wish you a lot of wins.

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AndyF
bike geek

That's a pretty big assumption.

I'd say the goal for most is to be the fastest they can be or fast enough to achieve their own personal goals and to do so within the constraints they have (genetic, resources, time, money etc). If it happens that's also the fastest of everyone on the day, then that's a nice bonus. But there are many different finish lines in this sport.

Your logic is actually not even accurate. The bottom line is that if you have aero gear then all things being equal you will beat more people in a race than if you did not have the aero gear. If there are two slow riders and one uses aero gear then that one will win.

You are essentially arguing that unless NO ONE else can beat you then aero gear is irrelevant because someone will beat you anyways.

I think the value of the information is in allocation of scarce resources for performance gains. Let's say you have $500 you plan to spend to get more aero. The numbers can help you figure out how best to allocate those (limited) funds into performance. I don't think anyone is really trying to determine the theoretical faster/slower time or drag savings a posteriori as you seem to be suggesting.

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Oh yeah!

I think what's getting him is the term "saves watts" as if the riders are going to be aiming for a certain speed and "spending less" watts to achieve that speed. It's kind of a misnomer since most riders don't ride that way but rather will ride their same normal target watts and gain more speed out of those same watts with the better race gear. Semantics. "Saves watts"... "Gains mph"... same thing.

Flac the only reason people bring up this "slower riders are on the course longer" math is because every time someone says "This wheel will save you about 5 seconds per 40k" it is immediately questioned if that is only the case for people going 30mph. It is a useful metric for people who are skeptical of the physics. It is useful for teaching them about aerodynamics and bikes.

So it is explained to them via a short explanation of math and physics that no, it will be the case for people going 20mph too.

If you don't think there is value in knowing, approximately, how much time a particular wheel might save you, well then we will have to agree to disagree.

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

This has already been stated several times but you seem to be missing it.

You weren't around here when every week someone would say, "my riding friends told me that aero benefits do not BEGIN until I'm riding faster than 25mph." That is when the smart STers would tell them that ACTUALLY, the time benefits of aero are GREATER at slower speeds. No one is saying that the goal is not to win or go faster, it was simply to counter the argument that drag does not exist below 25 mph.

Just wanted to say thanks to (most of) you all for the replies. Very helpful. You're right in that I'm not trying to 'save the most time possible' by going slow. And I think what Comida pointed out is relevant, that I probably shouldn't have termed it 'saving watts' because I'm not trying to go the same speed with fewer watts, rather I was trying to figure out how much faster I would be going pushing the same number of watts, which I think most of you get. In any event it's definitely not a 'useless metric' for me to know how much time I could reasonably expect (with a decent margin of error) to save by purchasing something based on a reasonable assumption of how fast I might be traveling come race day. I think far too few people have any idea how much (or little) time they're buying by going out and getting a $5k bike or a $2k set of wheels or a $150 helmet, or maybe the question doesn't get asked because they're not concerned about buying time, they're concerned about buying looks (something I do regularly, so no shame in that), but my goal is to educate myself so that when I see something that looks good I can justify buying it for reasons other than that :-) ....but that's all for another post.

Either way, you have all helped me understand the 'value' (in terms of time...roughly) of a few purchases that I may make. Much appreciated!

"So I don't know if I'm being trolled... but... "

^ THIS GUY

lol