Wheel info

[Peter@vecchios]

Still cold out and this is still a discussion forum so....

http://www.biketechreview.com/archive/wheel_theory.htm

 

[ScienceIsCool]

Hmmm. Actually, it would be neat to plot out measured power versus velocity for the ride profiles he's made and curve-fit to find out the different values of drag in his model. You could also come up with a good estimate of measurement error which would tell you a bit about whether any differences in setup would be lost in the noise, so to speak.

John Swanson
www.bikephysics.com

 

[ibi-m]

Roughly, the average rider power requirements on a course with a zero net elevation gain is broken down into 60% rider drag, 8% wheel drag, 8% frame drag, 12% rolling resistance .5% wheel inertia forces and 8% bike/rider inertia


comments on this one? is this accepted by the community?
thanks

equation of motion is absolutely correct, but it all depends on what you put in it.. I came across this one long ago, almost forgot about it... it would be great to see the curves for different velocities for comparison.. then again, this is free data, so we can't complain much.
les roues artisanales has plenty of wheels related info, some killing the myths about total wheel traction resistance...

http://www.rouesartisanales.com/article-15441821.html

 

[531Aussie]

Still cold out ]

HA!

It's 43.6C here (110.5)! Hottest day I can remember.

http://www.bom.gov.au/products/IDV60900.shtml

 

[531Aussie]

HA!

It's 43.6C here (110.5)! Hottest day I can remember.



".......and strong enough to get you to the finish line"

This is something which is often overlooked. I've heard a few bling wheels pop spokes in races lately.

 

[Phill P]

I'm surprised that frame aero is equal to wheel aero.

 

[parawolf]

I'm surprised that frame aero is equal to wheel aero.

I've heard - no reference available - that lowering your head by 2cm is the same aero gain as a set of fast wheels.

Don't shoot the messenger on that one... but given that the cyclist drag is so high, it has potential.

 

[531Aussie]

I'm not sure about 2cm, but on this German Tour Mag test (which I've posted a zillion times before ), the rider cut 59w of drag, moving from the hoods to the drops, but only cut 15w going from 32-spoke wheels to 2 tri-spokes




They first put Uwe Peschel on a 'normal' road bike

Required output to sustain 45km/h.

Stevens San Remo bike with hands on hoods: 465 Watts
Same bike, hands down on the drops: 406 watts
Same bike, Easton Aeroforce aero bars: 369 Watts
Same bike Triathlon position (5.5 cm lower bar, saddle forwards): 360 Watts
Same as above, with 2 carbon Tri-spoke wheels: 345 Watts

Cervelo Tri bike + Tri spoke wheels: 328w
Cervelo Tri bike + Tri spoke front + disk rear wheel : 320 w
Same as above with Giro aero helmet: 317w
Same as above with speed suit: 307w


Spekken la Doiych?
http://www.dk-content.de/tour/pdf-archiv/tests/zeitfahren_material_0107.pdf

Another one:

http://www.cervelo.com/reviews/aerotest.pdf

 

[Phill P]

What about with a low rider recumbent?

 

[ibi-m]

I'm not sure about 2cm, but on this German Tour Mag test (which I've posted a zillion times before ), the rider cut 59w of drag, moving from the hoods to the drops, but only cut 15w going from 32-spoke wheels to 2 tri-spokes



They first put Uwe Peschel on a 'normal' road bike

Required output to sustain 45km/h.

Stevens San Remo bike with hands on hoods: 465 Watts
Same bike, hands down on the drops: 406 watts
Same bike, Easton Aeroforce aero bars: 369 Watts
Same bike Triathlon position (5.5 cm lower bar, saddle forwards): 360 Watts
Same as above, with 2 carbon Tri-spoke wheels: 345 Watts

Cervelo Tri bike + Tri spoke wheels: 328w
Cervelo Tri bike + Tri spoke front + disk rear wheel : 320 w
Same as above with Giro aero helmet: 317w
Same as above with speed suit: 307w


Spekken la Doiych?
http://www.dk-content.de/tour/pdf-archiv/tests/zeitfahren_material_0107.pdf

Another one:

http://www.cervelo.com/reviews/aerotest.pdf

Same bike, hands down on the drops: 406 watts
Same bike, Easton Aeroforce aero bars: 369 Watts

very interesting - 10% less only because of different bars? care to elaborate, thanks

 

[Bro Deal]

What about with a low rider recumbent?

The recumbent takes off 98 Watts.

Unfortunately the required beard adds 105.

 

[531Aussie]

very interesting - 10% less only because of different bars? care to elaborate, thanks

that's going from normal bars to aero bars

 

[Phill P]

HA!

It's 43.6C here (110.5)! Hottest day I can remember.

http://www.bom.gov.au/products/IDV60900.shtml

So hot today the power keeps cutting out at work because too many AC units running across Melbourne. Train lines are buckling due to over expansion and half the trains aren't running.
3 days in a row of 43degC+, cold change tomorrow....only going to be 35 and 30 over the weekend.

 

[Bob Ross]

I've heard - no reference available - that lowering your head by 2cm is the same aero gain as a set of fast wheels.

I'm not sure about 2cm, but on this German Tour Mag test (which I've posted a zillion times before ), the rider cut 59w of drag, moving from the hoods to the drops, but only cut 15w going from 32-spoke wheels to 2 tri-spokes

I've cited it before, but I still get a kick out of that quote from the guy on the MIT cycling team, who, after evaluating wind tunnel data, pointed out that an aero helmet offers vastly improved performance gains over aero wheels: "So you could spend $2000 on wheels, or $200 on a helmet and be faster."

 

[parawolf]

I've cited it before, but I still get a kick out of that quote from the guy on the MIT cycling team, who, after evaluating wind tunnel data, pointed out that an aero helmet offers vastly improved performance gains over aero wheels: "So you could spend $2000 on wheels, or $200 on a helmet and be faster."

Hence why i've recently bought myself an aero lid... and own aero wheels...

Aero lids are only allowed on TT's and on the relevant track events so they get extremely limited use in Australia. A set of 404 or 808's (or similar from Edge, HED, etc) would get more race time by a factor of 10:1).

 

[dhk2]

I'm not sure about 2cm, but on this German Tour Mag test (which I've posted a zillion times before ), the rider cut 59w of drag, moving from the hoods to the drops, but only cut 15w going from 32-spoke wheels to 2 tri-spokes




They first put Uwe Peschel on a 'normal' road bike

Required output to sustain 45km/h.

Stevens San Remo bike with hands on hoods: 465 Watts
Same bike, hands down on the drops: 406 watts
Same bike, Easton Aeroforce aero bars: 369 Watts
Same bike Triathlon position (5.5 cm lower bar, saddle forwards): 360 Watts
Same as above, with 2 carbon Tri-spoke wheels: 345 Watts

Cervelo Tri bike + Tri spoke wheels: 328w
Cervelo Tri bike + Tri spoke front + disk rear wheel : 320 w
Same as above with Giro aero helmet: 317w
Same as above with speed suit: 307w


Spekken la Doiych?
http://www.dk-content.de/tour/pdf-archiv/tests/zeitfahren_material_0107.pdf

Another one:

http://www.cervelo.com/reviews/aerotest.pdf

15W by switching wheels is a substantial savings, but remember that's at 45 kph (28mph). Because aero drag power is a function of the cube of the speed, at a more typical pace, say 20 mph, the savings would only be be 36% of 15W, or ~5.4 watts.

Same factor applies to aero helmets, aero bars and all the rest. That's the reason this stuff makes sense for a fast TTer, not so much for a group ride at 20 mph or less.