Here is a little spreadsheet I put together that compares grams of drag saved vs grams of weight saved

There are two worksheets, one for a 250 watt effort, and one for a 350 watt effort. All equations assume a 75kg rider, you are a lot lighter than that, so speeds would be faster, shifting things towards aero for you on the uphills =)

It gives you an idea of when you might prefer a lighter part/frame/wheel over an more aero one, and the answer is NOT often. Only long, sustained hill climb events, or if you are giving up just a little aero for multiple kilograms of weight.


https://docs.google.com/...HZkeUJ2UW5DUlE#gid=0

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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

Thanks for the reply, but am I missing seeing a link to your spreadsheets?

Aero always trumps weight. To a point. Go slow enough and weight matters again. ie: climbing a steep, long hill, cyclocross where speeds rarely hit 15mph, etc.

For 'normal' riding an aero helmet and aero wheels will save you watts vs 'normal' wheels and a 'normal' helmet. The more watts saved the faster you ride.

HTH

M

Unless you are planning on doing tons of climbs over 6%, then aero is always the winner.

Aero bar mounted aero bottle, Zipp wheels, aero helmet, got them. So i guess it's back to the age old question of which aero bike delivers the most aero benefit at a reasonable weight. 10 years of tri's and du's, the majority on this bike, it just might be time for an upgrade. I have looked hard at the Trek SC9.9 and the Cervelo P5. Here we go... Any thoughts! ;-)

also would be interested in seeing that spreadsheet, but not seeing how...

should I necessarily be concerned with the overall weight of the bike or just make sure that what I buy is as aero as possible. Thanks for any insight.

Since you are so light, if you have the money and do TTs with climbs, it would make sense to consider weight somewhat. On a flatish road though, the lb or two you'd save is negligible. BTW, my TT bike weighs 23 lbs.

There are many calculators on the internet where you can determine the effect pretty precisely for your conditions. Here is one: http://www.whitemountainwheels.com/SpeedPower.html

I win Fat Boy Bike Weigh In: 24.5 lbs. in full race glory.

Sorry, here:
https://docs.google.com/...HZkeUJ2UW5DUlE#gid=0

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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

Based on the P4 vs Trek SC9.9 data I have seen, I would lean P5.

But the SC9.9 is awesome, and gets a bit lighter and more aero with the tririg.com aerobar mod. The SC draftbox is also pretty cool.

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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

My opinion is aero trumps weight.

I think areo frams look great...until you put a rider on it. Might be worth a few minutes in an IM? I'm talking a great position on each frame. Just not worth that much.

That is a good point, if only engineers were taking into account if these gains exist once you put a rider on an aero frame...









anyway a few minutes in an IM....that is a lot!

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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

it's not about the gradient, per se, but rather about speed. As another poster mentioned, 14-15mph seems to be where things get tilted in favor of weight. Now if you can put out more power, then there are more occasions on which you can use your deep wheels and suffer no penalties due to the heavier weight of the wheels.

at 250 watts going 16 mph up a 3% slope, a part that saves 50g of drag at 30mph saves you as much time as a part saves you 430grams of weight.

at 250 watts going 14mph up a 4% slope, , a part that saves 50g of drag at 30mph saves you as much time as a part saves you 250grams of weight.

The question of "when does weight matter more" really is a function of speed AND gradient. If the road is flat, even at very very slow speeds, aero still matters *much* more than weight.

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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

you the aero-maven summed it up a bit better than i did ;)

I took a look at the worksheet that you attached and I find it very helpful, Thanks. I agree that once you put a rider into the mix the drag coefficient is going to change. In reality, bikes don't race themselves, they all have riders. So that brings us back to aero trumps weight. How aero is one to another today with many of the newer models being classified as "Super Bikes". Remember, I'm riding a 6 year old rig and in a Slowtwitch review of my current bike the article even then could not say that the Plasma Pro was that great of an aero frame. Given my same power output, moving towards a SC or P5 or really any modern frame would equal faster speeds and lower times, yes?

you should be thanking Jack Mott, not me ;)

that said, regarding your second question, while i'm not sure if the tube shape of tri-bikes have significant effects when you have a rider on it, there was some test form earlier this year (forgot which application) that showed that once you put a rider on a road bike, there was no aero difference between the system of rider on a bike with aero tubes vs rider on a bike with standard tubes.

SIGNGUY,
I too had a 2006 Scott Plasma up until 2011. As I recall, that frame is very light, somewhere around 1100gr. Curious to know what parts you have built on it, and how it weighs what you say?

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Team Zoot-Texas, and Pickle Juice

All bikes have to have someone ride them. A slow frame, say an Kuota Kaliber, isn't going to become faster than a P3 just b/c you stick a rider on them. Faster is faster, you might make one a little faster or a little slower with the air interaction once you stick a rider on it, but you're not making the ugly duckling a princess.

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Brian Stover USAT LII
Accelerate3 Coaching
Insta

Not any modern frame, but any frame with low drag that supports your position, would result in faster speeds and lower times.

Probably not enough for you to notice unless you carefully measure things with a power meter and controlled conditions.

Whether you notice the advantage or not, has no bearing on whether it is there though.

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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

I did mean to give you the thanks for the worksheet from earlier Jack, again thanks. Touching then on what you just said about any frame with low drag that supports my position along with what Brian said, fast or slow frames, indicates some homework to see which frames have low drag numbers.

Thanks for the spreadsheet - good stuff. Am I thinking about this correctly given the below...

I live in very hilly Bloomington, Indiana - continuous uphill and downhill hiding (very few flat sections and downhills are often speed limited due to curves) so I went with lighter semi-aero wheels on my Titanflex build.


If I added a more aero wheelset like a Zip 808 (1730g claimed) vs my 1530g (actual) Rolf Vigor SL's I will gain approximately 50g drag reduction (my guess, but maybe a little more) with an approx. 1/2 pound weight increase (.44lbs = 200g)...

At what grade on the 250w effort tab is the breakeven point for the added 200g mass of the Zipp 808's? Looks like I would be ahead on the Zipps to at least 6% grades?

See pic below for typical riding conditions around Bloomington, IN (I would divide the Max incline reported by 2 to 2.5 for a rough average incline estimate of each hill). Many minutes at slower than 6mph on many of these hills...

It would be fun to create a "fatigue factor" due to heavier wheels from multiple sustained climbs under 6mph over a 50 mile ride such as below - I think this my offest aero time savings in your file, but that's probably a whole other issue!

GTO scott - to get deeper into this you can run over to AnalyticCycling.com and run some simulations of your routes.

One thing to consider is that some of these hills are only .1 and .2 miles long. Optimum power pacing would dictate you do quite a bit higher than your average goal power for the route up those, so 250 watts might not be right, unless your goal average power is ~200. Especially since the downhills are limited by curves. So you might go ~300, ~400 watts up and 0 watts down.

Also consider that if it is windy, all these numbers get shifted toward the aero side. The data in the spreadsheet assumes no wind.

I would probably guess more like ~100 to ~150g drag savings comparing 808 to the Rolf Vigor as well.

Perhaps it is a good course for the Zipp 404 or 303!

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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