Weight Vs Aerodynamics -Wheelset Selection

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Re: Weight Vs Aerodynamics -Wheelset Selection

Postby Xplora » Thu Jan 31, 2013 1:38 pm

twizzle wrote:Thanks for the detailed explanation, Alex.

Worst part is that aero is THE hardest thing to actually measure, despite being the most critical thing! Unless you were able to put a wheel on and get a bloke to hold 200 w around a roofed velodrome, I can't see how you can test the aero?
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by BNA » Thu Jan 31, 2013 1:45 pm

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Re: Weight Vs Aerodynamics -Wheelset Selection

Postby TDC » Thu Jan 31, 2013 1:45 pm

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Re: Weight Vs Aerodynamics -Wheelset Selection

Postby __PG__ » Thu Jan 31, 2013 2:20 pm

TDC wrote:http://en.wikipedia.org/wiki/Wind_tunnel

:lol:

Requires a rolling road, low blockage ratio, lots of instrumentation and experienced users to be of any use.
Even F1 teams lose calibration of their tunnels from time to time and sometimes they end up making the car go slower.
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Re: Weight Vs Aerodynamics -Wheelset Selection

Postby TDC » Thu Jan 31, 2013 2:26 pm

Ok. What is the Blockage ratio?
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Re: Weight Vs Aerodynamics -Wheelset Selection

Postby __PG__ » Thu Jan 31, 2013 2:40 pm

If you stick a too large object into a too small tunnel, the results are not representative of the real world. The walls will force the flow to artificially accelerate faster over the object than they would do in a free atmosphere.
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Re: Weight Vs Aerodynamics -Wheelset Selection

Postby TDC » Thu Jan 31, 2013 2:55 pm

cheers
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Re: Weight Vs Aerodynamics -Wheelset Selection

Postby ausrandoman » Thu Jan 31, 2013 3:23 pm

For what its worth, I'm a physicist by training and I've been riding for 40 years.

I use light weight wheels for mountain rides and for windy days. Otherwise, I use moderately aero eheels. You might have different preferences.
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Re: Weight Vs Aerodynamics -Wheelset Selection

Postby Xplora » Thu Jan 31, 2013 7:18 pm

TDC wrote:http://en.wikipedia.org/wiki/Wind_tunnel

:lol:

as per PGs post, the issue is cost. A set of digital scales is 20 bucks and no training required. A wind tunnel is 200,000 dollars plus training. It might be critical to any speed focused pursuit, but it is definitely the hardest thing to test. I would be satisfied with modeled dynamics on the PC but who will release that? :lol: it is trade secret stuff, commercial R&D, break your company information. Have to just assume that Zipp isn't lying....
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Re: Weight Vs Aerodynamics -Wheelset Selection

Postby TDC » Thu Jan 31, 2013 7:28 pm

Xplora wrote:
TDC wrote:http://en.wikipedia.org/wiki/Wind_tunnel

:lol:

as per PGs post, the issue is cost. A set of digital scales is 20 bucks and no training required. A wind tunnel is 200,000 dollars plus training. It might be critical to any speed focused pursuit, but it is definitely the hardest thing to test. I would be satisfied with modeled dynamics on the PC but who will release that? :lol: it is trade secret stuff, commercial R&D, break your company information. Have to just assume that Zipp isn't lying....


The Specialized/McLaren collaboration is understandable when you consider the above numbers.
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Re: Weight Vs Aerodynamics -Wheelset Selection

Postby Xplora » Thu Jan 31, 2013 7:41 pm

TDC wrote:
Xplora wrote:
TDC wrote:http://en.wikipedia.org/wiki/Wind_tunnel



The Specialized/McLaren collaboration is understandable when you consider the above numbers.

I think we will see more of these in future.... The cost of the top Venge really subverts the entire process though. Seems like they wanted an excuse for rich twits to waste money rather than actually create a real F1 meets bike hybrid. Maybe that is the point. I don't like F1 :!: :mrgreen:
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Re: Weight Vs Aerodynamics -Wheelset Selection

Postby warthog1 » Thu Jan 31, 2013 7:43 pm

Alex Simmons/RST wrote:
winstonw wrote:
Alex Simmons/RST wrote:Now if you are comparing objects that have a different masses (nothing suggests an aero wheel has to be heavier than a less aero wheel)


except maybe price, durability....and the title of the thread.

If your explanation covered all bases Alex, everyone would be riding discs, front and rear at 2+kg.

Perhaps you missed my earlier post on this thread wrt factors involved in wheel choice :roll:

viewtopic.php?p=915616#p915616


You are a very patient man , Alex.

Thanks for the great explanation. :)
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Re: Weight Vs Aerodynamics -Wheelset Selection

Postby winstonw » Thu Jan 31, 2013 8:36 pm

Alex Simmons/RST wrote:Perhaps you missed my earlier post on this thread wrt factors involved in wheel choice :roll:

viewtopic.php?p=915616#p915616


If your explanation covered all bases Alex, everyone would be riding discs, front and rear at 2+kg.
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Re: Weight Vs Aerodynamics -Wheelset Selection

Postby twizzle » Fri Feb 01, 2013 8:15 am

winstonw wrote:
Alex Simmons/RST wrote:Perhaps you missed my earlier post on this thread wrt factors involved in wheel choice :roll:

viewtopic.php?p=915616#p915616


If your explanation covered all bases Alex, everyone would be riding discs, front and rear at 2+kg.


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Re: Weight Vs Aerodynamics -Wheelset Selection

Postby __PG__ » Fri Feb 01, 2013 8:59 am

winstonw wrote:
Alex Simmons/RST wrote:Perhaps you missed my earlier post on this thread wrt factors involved in wheel choice :roll:

http://www.bicycles.net.au/forums/viewt ... 16#p915616


If your explanation covered all bases Alex, everyone would be riding discs, front and rear at 2+kg.


Except that
a) Real-world road cycling has variable winds
b) Most punters don't need to ride around at 50 km/h

Track riders use discs (sometimes two).

Personally, for a recreational rider I think 'aero' bikes and wheels are a complete waste of time for the following reasons.
1) Deep carbon clincher wheels weigh the same as shallow alloy wheels
2) The frontal area of a racing wheel (or a frame for that matter) where the flow separates from is minuscule compared to the frontal area of a large out-of-shape rider who rides with a flipped stem, spacers and can't ride with a flat back.
3) A set of small clip-on bars (a la Cinelli Spinaci) will give a recreational rider a much more aerodynamic advantage than deep wheels
4) As would using a camelbak instead of two water bottles

But that's just my opinion.

If I started racing I'd get some carbon tubulars ASAP - but that's partly for the weight advantage as well as for the small aerodynamic gains.
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Re: Weight Vs Aerodynamics -Wheelset Selection

Postby winstonw » Fri Feb 01, 2013 9:14 am

__PG__ wrote:Except that
a) Real-world road cycling has variable winds
b) Most punters don't need to ride around at 50 km/h


...and except that Bradley Wiggins didn't use his 2012 TdF TT wheels for any of the other stages.
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Re: Weight Vs Aerodynamics -Wheelset Selection

Postby __PG__ » Fri Feb 01, 2013 9:19 am

winstonw wrote:
__PG__ wrote:Except that
a) Real-world road cycling has variable winds
b) Most punters don't need to ride around at 50 km/h


...and except that Bradley Wiggins didn't use his 2012 TdF TT wheels for any of the other stages.

Does he need to? Sitting in the middle of the peleton for most of the route?
Climbing at 20-30 km/h?
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Re: Weight Vs Aerodynamics -Wheelset Selection

Postby zero » Fri Feb 01, 2013 9:38 am

winstonw wrote:
__PG__ wrote:Except that
a) Real-world road cycling has variable winds
b) Most punters don't need to ride around at 50 km/h


...and except that Bradley Wiggins didn't use his 2012 TdF TT wheels for any of the other stages.


Have a gander at the current UCI mass start reg's and allowed wheels and report back to us if he was allowed to use them.
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Re: Weight Vs Aerodynamics -Wheelset Selection

Postby mjd » Fri Feb 01, 2013 10:35 am

Lol at some people!
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Re: Weight Vs Aerodynamics -Wheelset Selection

Postby jacks1071 » Fri Feb 01, 2013 10:53 am

zero wrote:
winstonw wrote:
__PG__ wrote:Except that
a) Real-world road cycling has variable winds
b) Most punters don't need to ride around at 50 km/h


...and except that Bradley Wiggins didn't use his 2012 TdF TT wheels for any of the other stages.


Have a gander at the current UCI mass start reg's and allowed wheels and report back to us if he was allowed to use them.


TT isn't a "mass start" event and as such is except from mass start rules.
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Re: Weight Vs Aerodynamics -Wheelset Selection

Postby Alex Simmons/RST » Fri Feb 01, 2013 11:27 am

Testing the aerodynamics (and rolling resistance for that matter) of different wheels is not all that difficult if you have an on bike power meter.
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Re: Weight Vs Aerodynamics -Wheelset Selection

Postby Alex Simmons/RST » Fri Feb 01, 2013 11:46 am

winstonw wrote:
Alex Simmons/RST wrote:Perhaps you missed my earlier post on this thread wrt factors involved in wheel choice :roll:

viewtopic.php?p=915616#p915616


If your explanation covered all bases Alex, everyone would be riding discs, front and rear at 2+kg.


As is typical with your tiresome strawman arguments, can you point out where I made a claim during my explanation on the specific question of the interplay of forces during an acceleration on a bicycle that it covered all bases with respect to wheel choice?

I've made it quite clear in this thread that wheel choice is a function of many things aside from mass and aerodynamics, and provided detailed information and a good link to a great information resource to help people avoid a common error in weighing up those factors when deciding what's the best choice for them, all things considered.

Do you have anything constructive to add?
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Re: Weight Vs Aerodynamics -Wheelset Selection

Postby winstonw » Fri Feb 01, 2013 12:13 pm

Alex Simmons/RST wrote:Do you have anything constructive to add?


you provided an overly simplistic application of a few physics equations that does not reflect real world riding conditions.
you state aerodynamics is a more influential variable than wheel weight, with acceleration from 0kph.
you confidently imply aero is always more influential than wheel weight, when climbing up all but the steepest of hills.

I don't buy unqualified absolutist generalizations.
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Re: Weight Vs Aerodynamics -Wheelset Selection

Postby sogood » Fri Feb 01, 2013 12:37 pm

Xplora wrote:And the magic being that you can buy that wattage rather having to train for it ;)

You aren't talking about EPO again are you? ;)
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Re: Weight Vs Aerodynamics -Wheelset Selection

Postby __PG__ » Fri Feb 01, 2013 1:44 pm

Alex Simmons/RST wrote:Testing the aerodynamics (and rolling resistance for that matter) of different wheels is not all that difficult if you have an on bike power meter.

You can also do on-road flow visualisation tests using wool tufts and oil/powder mixtures for non-rotating areas of the frame and rider.
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Re: Weight Vs Aerodynamics -Wheelset Selection

Postby warthog1 » Fri Feb 01, 2013 2:03 pm

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