Wheel Aerodynamics

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The total power required to ride a bike is:

Power lost to aerodynamic drag: (½rhoCdAVA³)
Power loss from rolling resistance of tires: (CRRWTVG)
Power to rotate wheels (FwVG³)
Power to overcome gravity on a hill (WTVGsin(arctan(RoadGrade)) (varies greatly)
Friction losses in the drive and bearings (small except for chain line cross over)
Power to accelerate and power losses from deceleration (converted to heat).

Power required = ½rhoCdAVA³ + CRRWTVG + FwVG³ + WTVGSin(Arctan(RoadGrade)

Aerodynamic drag represents the largest resistance while riding over level ground.

UCI Wind Tunnel Data
Wheel Name	Weight (g)	Rotating Drag(g)

24" Wheel
Trialist Flat Carbon Disk	950	97
Accel Kevlar Lens Disk	480	100
Vortex 12 Spoke Prototype	790	109
Hooker 18 Aero Spoke, Aero Rim	490	136
Elite 18 Aero Spoke, Aero Rim	500	154


650c Wheel
26" Accel Kevlar Lens Disk	590	95
Trialist Flat Carbon Disk	900	101
26" HED CX 18 Aero Spoke	850	139
Elite 18 Aero Spoke, Aero Rim	530	145


700c Composite Spoke Wheel
Aerosports 3-spoke Prototype	720	106
Trispoke (3-spoke)	720	112
Specialized (3-spoke)	1330	114
Zipp (3-spoke)	850	129
Corima (4-spoke)	1590	131
FIR Halley (3-spoke)	1530	142

700c Disk Wheel
Gipiemme Lens Disk	1107	101
Trialist Flat Carbon Disk	1035	105
Carbotec Lens Disk	1135	108
Spengle Lens Clincher Disk	1480	109
Zipp 950 Carbon Flat Disk	950	112
HED Flat Carbon Disk	1050	114
Accel Kevlar Lens Disk	710	118
Radsport Lens Disk	1900	123

700c Steel Spoke Wheel
Roval 18 Aero Spoke, Aero Rim	680	149
Elite 18 Aero Spoke, Aero Rim	580	162

University of Bath, UK (Cycling Plus):

The following were measured over a range of crosswind angles:

axial force coefficient	C_x	= Fx / (0.5 rho V² S)
side force coefficient	C_y	= Fy / (0.5 rho V² S)
yawing moment coefficient	C_n	= Mz / (0.5 rho V² S D)
	rho = air density V = air speed S = reference area D = diameter

axial force coefficient C_x
Wind Angle:	0.0	7.5	15.0	22.5	30.0	37.5	45.0	55.0	65.0
Conventional 36-spoke	0.047	0.057	0.061	0.059	0.058	0.070	0.057	0.045	0.029
Campagnolo Shamal	0.037	0.047	0.043	0.045	0.036	0.028	0.018	0.010	0.000
HED CX 24-spoke	0.035	0.028	0.034	0.041	0.042	0.039	0.030	0.019	0.011
Specialized TriSpoke	0.036	0.038	0.028	0.031	0.028	0.020	0.009	0.006	-.001
FIR TriSpoke	0.036	0.026	0.034	0.041	0.037	0.032	0.020	0.011	0.002
HED disk (lenticular)	0.036	0.020	-.004	-.005	0.000	0.001	-.003	-.005
ZIPP 950 disk (flat)	0.036	0.023	0.013	0.017	0.018	0.017	0.016	0.016

Vendor Data

Brand 0° Yaw 5° Yaw 15° Yaw 30° Yaw Side Force (45°) Wheel Speed = 29 MPH
Air Speed = 29 MPH

Drag at 0°, 5°, 15°, 30° yaw measured
in the plane of the wheel in grams
(Error ± 5 grams)

Side Force drag measured in
the plane of the wind in grams
(Error ± 10 grams)

Note: The lower the Side Force, the less effect a cross wind has on bicycle handling.

Source XNG!

XNG! 55 61 74 80 344

Campagnolo Shamal 52 61 78 88 346

Campagnolo Vento 53 63 80 93 355

Mavic Pro 53 64 79 92 349

Campagnolo Bora 55 68 81 94 346

Corima 55 68 81 94 346

Mavic Expert 56 69 84 103 358

Gipiemme 57 70 80 88 347

Ambrosio 57 70 80 87 348

Torelli Wide Guy 57 65 85 96 350

F.I.R. 57 70 80 87 346

Zipp 340 65 67 77 81 338

Am Class Vrim low profile 65 67 77 81 338

HED CX 67 69 78 85 369

HED Jet 68 70 78 85 372

Zipp 440 68 70 80 88 370

Am Class Vrim Tubular 68 70 80 88 370

Zipp 530 68 72 81 89 378

Am Class Vrim Clincher 68 72 81 89 378

Giant Carbon Road 68 71 77 97 431

Cosmic Carbon 68 71 78 86 370

Zipp 950 flat disk 75 70 60 211 1422

HED Flat disk 77 71 57 200 1387

Mavic Comete flat disk 77 73 57 204 1394

Specialized Ultralight 78 72 70 68 460

Nimble 79 74 70 64 383

Aerospoke 79 92 99 109 411

Spinergy Rev-X 84 73 71 70 457

Corima 4 spoke 94 88 80 74 526

Trek/Rolf 98 107 110 114 383

Spengle 3 spoke 108 101 94 89 399

Wheelsmith Accelerator 111 121 134 141 331

Cane Creek Crono 112 121 135 142 330

Mavic Helium 233 238 244 249 317

Wheel Questions? Try BSn's WWW Bicycle Technology Forum (VeloTech).

Brand	0° Yaw	5° Yaw	15° Yaw	30° Yaw	Side Force (45°)	Wheel Speed = 29 MPH Air Speed = 29 MPH Drag at 0°, 5°, 15°, 30° yaw measured in the plane of the wheel in grams (Error ± `5` grams) Side Force drag measured in the plane of the wind in grams (Error ± 10 grams) Note: The lower the Side Force, the less effect a cross wind has on bicycle handling. Source XNG!
XNG!	55	61	74	80	344
Campagnolo Shamal	52	61	78	88	346
Campagnolo Vento	53	63	80	93	355
Mavic Pro	53	64	79	92	349
Campagnolo Bora	55	68	81	94	346
Corima	55	68	81	94	346
Mavic Expert	56	69	84	103	358
Gipiemme	57	70	80	88	347
Ambrosio	57	70	80	87	348
Torelli Wide Guy	57	65	85	96	350
F.I.R.	57	70	80	87	346
Zipp 340	65	67	77	81	338
Am Class Vrim low profile	65	67	77	81	338
HED CX	67	69	78	85	369
HED Jet	68	70	78	85	372
Zipp 440	68	70	80	88	370
Am Class Vrim Tubular	68	70	80	88	370
Zipp 530	68	72	81	89	378
Am Class Vrim Clincher	68	72	81	89	378
Giant Carbon Road	68	71	77	97	431
Cosmic Carbon	68	71	78	86	370
Zipp 950 flat disk	75	70	60	211	1422
HED Flat disk	77	71	57	200	1387
Mavic Comete flat disk	77	73	57	204	1394
Specialized Ultralight	78	72	70	68	460
Nimble	79	74	70	64	383
Aerospoke	79	92	99	109	411
Spinergy Rev-X	84	73	71	70	457
Corima 4 spoke	94	88	80	74	526
Trek/Rolf	98	107	110	114	383
Spengle 3 spoke	108	101	94	89	399
Wheelsmith Accelerator	111	121	134	141	331
Cane Creek Crono	112	121	135	142	330
Mavic Helium	233	238	244	249	317