Upright position - aero as a brick?

Discuss light weight issues concerning road bikes & parts.
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wheelsONfire
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by wheelsONfire

I guess aero has been rambled about to a point some of you guys almost get mad about another of these threads.
Please, don't argue about that!
I can't help wondering or should i say questioning the benefits of aero bikes, handlebars aso.
Ok, wheels i might believe to some degree, but not like night and day.
Let's say you got a guy like me, i can touch my toes fairly easy, so i'm not as a refrigerator.
But through learning i have come to understand i am best off with a 70-80mm saddle to bar drop if i wish to really use the drops to.

I accept the outcome of my fit, finally.

I read for every cm you lower your body there are gains, i guess supersede a fancy aero frameset?

If you average below 30km/h riding solo (i always ride solo) aswell as ride a fairly upright position.

How can aero help?

If it does, what degree would it be?

I don't notice any better average in speed going from 38mm depth to 55mm aero wheels.

Wouldn't a lower weight bike allow me to save energy since there is less mass to move around?
Bikes:

Ax Lightness Vial EVO Race (2018.12.21)
viewtopic.php?f=10&t=156137
Paduano Racing Fidia (kind of shelved)
Open *UP* (2016.04.14)


Ex bike; Vial EVO D

Marin
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by Marin

Rim depth will only make a tiny difference.
Weight will only make a tiny difference, and only over routes with lots of climbing.

Aero will make a lot of difference, easily several kph. Do you have a power meter? Hold the same power at 30kph, and ride on the tops, then switch to the hoods with forearms horizontal and a flat back. You'll be doing 33-34kph.

You can still be more areo by going narrower instead of lower - grabbing the center of the tops will help. Wearing a speedsuit and an aero helmet will help too.

by Weenie


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wheelsONfire
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by wheelsONfire

I have no power meter and i guess i will never have one. Not going into why.
I am a believer of comfort as top prio.
Voiding fatigue of muscles as much as possible.
There can never be too much of it with a somewhat quick road bike.
It's still made for speed.
I would like to try an aero bike.
But if so, still for where i am talking fit.
However, most bikes today are low and long.
My current is 57.8mm stack + 4mm spacer + headset height 3mm
Reach is a bit too long at 394mm.
But the aero bikes, puh they're several cm's lower...
Bikes:

Ax Lightness Vial EVO Race (2018.12.21)
viewtopic.php?f=10&t=156137
Paduano Racing Fidia (kind of shelved)
Open *UP* (2016.04.14)


Ex bike; Vial EVO D

hambini
Posts: 493
Joined: Tue Nov 15, 2016 8:13 am
Location: Cologne, Germany

by hambini

The biggest aerodynamic defecit on your bike is your body.

To simplify the technicalities a little, you can consider drag to be made up of two things,

Your frontal area, so the lower you go, the more reduction this has

The Drag coefficient of your body shape. As you get lower, your drag coefficient drops because air is attached for longer. A flat back makes the air detach further downstream so you get less drag.

To put it into perspective, the difference between going from an upright position to an Aero position, that difference cannot be overcome by technology (ie bike frame, wheels etc).

I have a youtube video about bike position, it might be worth a look.

Thanks

Hambini
Hambini Aeronautical Engineer, Polluting YouTube since 2016 - views expressed are my own...
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Aerodynamic Masterclass in bicycle wheels
I fixed the bottom bracket from hell

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Lelandjt
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Joined: Tue Jan 19, 2016 7:10 am

by Lelandjt

At sub 20mph I know the difference in effort/speed made by aero exists but I can't feel it, so I don't think you'll notice any difference if you don't use a power meter and don't time rides. Above 20mph I can feel a difference and above 25mph I feel a BIG difference. I have a very aero bike and a bike with nothing aero, both with the same position. I feel like I hit a wall at 25mph on the non-aero bike that doesn't exist on the aero bike.

Based on this I'd say you ride to slowly to worry about aero unless you want to go faster, especially considering your preference for comfort.

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wheelsONfire
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Location: NorthEU

by wheelsONfire

I understand there is a (more or less) sweet spot and beyond that things start to happen.
However, the resistance is what it is when you are in a sportive position.
Used a foil back in the days, but i could not stand that bike. Far to harsh for me.
I couldn't really perform well when i got uncomfortable (pain)!
Only frame i see at this date, that have a nice geo is Cervelo S3.
Bikes:

Ax Lightness Vial EVO Race (2018.12.21)
viewtopic.php?f=10&t=156137
Paduano Racing Fidia (kind of shelved)
Open *UP* (2016.04.14)


Ex bike; Vial EVO D

User avatar
wheelsONfire
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Location: NorthEU

by wheelsONfire

hambini wrote:
Fri Aug 10, 2018 12:32 pm
The biggest aerodynamic defecit on your bike is your body.

To simplify the technicalities a little, you can consider drag to be made up of two things,

Your frontal area, so the lower you go, the more reduction this has

The Drag coefficient of your body shape. As you get lower, your drag coefficient drops because air is attached for longer. A flat back makes the air detach further downstream so you get less drag.

To put it into perspective, the difference between going from an upright position to an Aero position, that difference cannot be overcome by technology (ie bike frame, wheels etc).

I have a youtube video about bike position, it might be worth a look.

Thanks

Hambini
Hola Hambini

that is what i was aiming at. The relevance of aero frame, handlebar etc when you really are not aero.
For me, that is real world scenario. It doesn't really matter what happens if you are positioned in a manner you simply will never be in.
The relationship of bike and rider, should be considered from position that is and not what could be.
My question is what the bike itself would do.
Bikes:

Ax Lightness Vial EVO Race (2018.12.21)
viewtopic.php?f=10&t=156137
Paduano Racing Fidia (kind of shelved)
Open *UP* (2016.04.14)


Ex bike; Vial EVO D

gramsqueen
Posts: 69
Joined: Wed Jun 27, 2018 5:15 am

by gramsqueen

A buddy put on just aero wheels. He said it was harder to get off the line but easier to maintain speed

I’d imagine aero is somewhat analogous to horsepower and weight to low end torque. The point being the less restriction each parameter gives the rider ultimately nets him higher numbers in those two variables

AJS914
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Joined: Tue Jan 28, 2014 6:52 pm

by AJS914

wheelsONfire wrote:
Fri Aug 10, 2018 10:55 am
If you average below 30km/h riding solo (i always ride solo) aswell as ride a fairly upright position.

How can aero help?

If it does, what degree would it be?
https://www.youtube.com/watch?v=VHsLMCTkFso

Cycling Weekly did an aero wheel test and they came up with 2 k/mh @ 200 watts. I don't want to have a discussion of the pros and cons of their test but lets say that the savings is 1 km/h @ 100 to 150 watts which would be a regular guy's normal riding pace.

So for every hour you ride you will be 1km ahead. If you were participating in a 3 hour race being 3km ahead would be a huge advantage. But if you are riding alone you just ride for an extra couple of minutes to cover those 3km. There is no real world benefit.

I think regardless of your position an aero bike, aero wheels, aero helmet, aero skin suit, etc. will help you gain time but unless you are racing where the time is meaningful none of that equipment is worth paying extra for and, additionally, some of the aero equipment comes with tradeoffs (expense, comfort, weight).

Personally, I was thinking about some aero upgrades as I'm now doing group rides where I'm often at my limit at 25-27mph. I found a blog that translated all this into watts. When you add it up it's an enormous amount of watts: 22 for aero bike, 23 for aero wheels, 10 for aero helmet, etc.

https://www.shopforwatts.co.uk/blogs/ne ... s-it-worth

Being able to do that 25mph and have it require 20 to 50 less watts is certainly an attractive proposition.

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ergott
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by ergott

wheelsONfire wrote:
Fri Aug 10, 2018 1:05 pm
I can't help wondering or should i say questioning the benefits of aero bikes, handlebars aso.
Ok, wheels i might believe to some degree, but not like night and day.

I understand there is a (more or less) sweet spot and beyond that things start to happen.
My biggest gripe about aero discussions is that people think there's some sort of way that physics turns on and off. If aerodynamic gains can be made with wheels, why not any other compononent?

Aerodynamic benefits don't start/stop at any given speed. They always contribute.

After getting that off my chest I'll go on to say similar things to other posts. the magnitude of any aerodynamic benefits has to be looked at carefully. Most times, the difference between the more optomized setups and your basic round tube bike (think Cannondale CAAD frame) with low profile wheels is going to be 1km/hr tops and that's at high speeds. The slower you go, the smaller the difference, but because you are out on course longer you actually see a bigger percentage gain in time saved. As stated above, it's a couple minutes at best for a long ride. For most people this is unimportant and without a stopwatch/gps/bike computer you couldn't tell.

There are times where I personally prefer to seek as many aerodynamic gains as I can including my position on the bike. My head is lower than most people's shoulders so not only do I hide behind people better, I don't give them as much of a break from the wind when I'm on the front. When I'm leading and the speed is in the mid to upper 20s (mph) I do like having deep wheels and soon a real aero bike (waiting for parts). It might be only relatively small gain compared to my body position on the bike, but I've been known to spend up to 30 minutes on the front for a pull. Even 15 watts saved at that power output can mean the difference between burning too big of a match and sustaining the effort with some gas still in the tank for later.

mattr
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Location: The Grim North.

by mattr

ergott wrote:
Fri Aug 10, 2018 8:31 pm
Aerodynamic benefits don't start/stop at any given speed. They always contribute.
Not quite that simple. Some things get more aero as speed increases, some get less aero and below certain speeds, the difference can trend to zero. Depending on what part you are talking about. And how it's been designed.

Though to be fair, aero is one of those things that is relatively cheap to fix, as the huge majority of it is relatively low hanging fruit. Things like position, clothing, helmet can potentially get you far more watts than the high cost items (wheels and frame).

by Weenie


WheelNut
Posts: 23
Joined: Fri Jun 22, 2018 11:51 pm

by WheelNut

Hmmm, you're concerned about aero, but you can't get into an aero position and you only ride alone. I'm not going to ask why, or what your motivations are, because they don't really matter in regards to your question. It does seem to me though that evaluating the necessity of buying speed when riding by yourself might be something to do some thinking about. It's the hot part of the year, so a nice calm night ride might be a good time for contemplation :P :noidea: Of course, maybe you're like me and you just constantly think about how the machine is working underneath you as you ride along, then I certainly understand your curiousity!

There are many resources out there to learn about bicycle aerodynamics. I would suggest starting with Specialized "Win Tunnel" videos. https://www.youtube.com/playlist?list=P ... SCDKCKR97t
Buying speed, from what I can tell, goes roughly in this order: 0. Ride a recumbend or get a fairing (much more effective than any UCI legal stuff by a huge huge margin) 1. Skin suit 2. Aero helmet 3. Aero wheels 4. Aero frame 5. Low rolling resistance tires 6. Aero shoe covers 7. Aero small bits (skewers etc)
Josh Poertner has some good insights in some recent CyclingTips podcasts: https://cyclingtips.com/2018/08/walking ... -poertner/
Lots of good info in this book that will answer some of your questions: https://www.amazon.ca/Bicycling-Science ... B00MG7E628
Chris Yu discussing aerodynamics on the Velonews Podcast: https://www.velonews.com/2018/05/podcas ... ero_465167
Damon RInard on aero and the development of the System 6: https://redkiteprayer.com/2018/06/the-p ... on-rinard/

Its highly likely that the answer to your original question is buried in one of those podcasts, videos or articles. I know I've seen/heard the numbers, but I can't recall them off the top of my head.

Your questions:
I read for every cm you lower your body there are gains, i guess supersede a fancy aero frameset?
Aero parts, frames, wheels, etc all add up together when considering aero drag reduction. They are cumulative. That is to say yes getting a low riding position will make you go faster on any bike be it an aero bike, a road bike, or a step through rental city bike.

How can aero help?
You go a little bit faster for the same energy expenditure.

If it does, what degree would it be?
Highly variable. Please refer to scientific studies.

Wouldn't a lower weight bike allow me to save energy since there is less mass to move around?
Yes. Weight reduction will make the bike easier to accelerate and less aero drag will make the bike easier to keep at a given speed. A light AND aerodynamically efficient bike is doubly fast.

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