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Text Box: “Tour Magazine” Wheel Aerodynamics Test. 

The German bike magazine "Tour" (www.traxxx.de/tour) has tested 10 Aero-Wheels in the issue Nr.9 from September 96. I' ll try to translate the article and summarize the main aspects:
  
 THE TEST:The wheels were tested on a Faggin - frame, which was equipped with the SRM - measure technic. the special crank is a special edition of the well known SRM - crank: with 24 "flexible measurement stripes"("Dehnme§streifen") between crank and chain- wheels it seizes precisely, how strong the cyclist pushes and calculates the impulse power. The computer at the handlebar records the driving power of the cyclist and the speed.
  
 The test - cyclist (Lars Teutenberg, a German professional) had to drive several times several rounds at the exact speed of 45 kmh; after every test the data of the SRM - measure technic were transferred on a computer. This way all wheel - units were measured.
  
 To create equal conditions, all wheels had the same tires with the same pressure. a special construction on the saddle forced the test - cyclist to maintain just one certain position. The tester was alone on the course to avoid turbulences in the air. Other given Parameters were a chain wheel with 53 x 15 teeth ( ca. 102, 5 rounds per minute ) and a constant temperature of 22¡C.
  
 DISCS: Very big advantage of the concurrence. 12,7 % less power needed 
( with 45 kmh) than conventional wheels with 36 round shaped spokes ( 2 mm ) and angular rims/ conventional rims.
  
 In Numbers: instead of 403 Watt the driver just needs 352 Watt and saves 51 Watt.
  
 CHEAP AND FAST HIGH PROFILE AERO SPOKE - WHEELS: on the second rank are the Campagnolo 12 - spoke wheels, type "Shamal". The high profile rim with less spokes saves 9,7 % power compared to conventional wheels during a test. The following ranks show Mavic Cosmic, Citec and Spinergy. The relationship between Cosmic and Shamal does explain the similar results. The rims are equally high, but Mavic uses 16 instead of 12 spokes. On the same niveau are the 12 spoke wheels of Citec with very much lower rim. Ergo: the height of the rim is not the only criterion for good aerodynamics. Fitting to this result the Spinergy wheels ( extreme profiled rim with 8 plain carbon - spokes between rim and hub) and the HED - wheels ( high volume rims with carbon encased, 2 x 28 spokes ) test a bit worse, because they do not manage to tame the wind.

SURPRISINGLY GOOD:  Messerspeichen/ AERODYNAMIC SPOKES:
 A good result was achieved by a Wheel - set of Rigidas DP - 18 - rims ( average profile ) with 18 respectively 24 aerodynamic spokes.  Reaching the same results like distinctively more expensive constructions the wheels take a very good rank by using a higher rim profile and less, aerodynamic shaped spokes. Although the wheel can easily be managed in repairs and is just a little bit more expensive than usual wheels.  Until more precise tests take place it seems that 18 respectively 24 spokes can bear a weight of the cyclist
 up to 75 kg. More spokes on the back wheel are efficient if the cyclist has more weight or takes extreme stresses. If one takes a 40 mm rim with 18/24 spokes like FIR, Basso and others from the beginning, the more stiff rim profile gives enough security and good aerodynamics.
  
 LESS ADVANTAGE: TRI - and FOURSPOKES: not many specimen tested.
 Delivery Problems ( Spezialized, Habo ), production stops ( Spin wheel, Mavic, Zipp ) and other impediments left only three wheels to be tested. With 6,7 % less need of power Spengle takes the last rank within the complete sets. The single Corima - front wheel, tested with a  36 spokes back wheel is compared to the combination Shamal - front wheel/ 36 spokes back wheel worse, too.. the results show the problems of this type of wheel: carbon wheels are expensive and relatively heavy; the aerodynamics are worse than amongst the spoke wheels. 
  
 SET OR SINGLE ?:The measure results show that the back wheel is very important for the aerodynamics of the combination bike/ cyclist. The actual test shows that the Shamal set saves 39 Watt,  the front wheel alone with a 36 spokes back wheel only 18 Watt. This suggests that back wheel could save even more energy. BUT: due to possible failures in the measurements and the actual small data - basis a final conclusion could not be made. Only the tendency that both wheels are equally important for the aerodynamics seems to be provable.

30 Kph-18Mph

 

Power

Watts

Disk

125

Shamal 12 Spoke

129

Cosmic 18 Spoke

129

Citec 12 Spoke

129

Spinergy

130

HED Jet

132

Rigida 18 Spoke

132

Spengle Tri-Spoke

132

Shamal FW/36S BW

135

Corima VR/36S BW

136

Standard 36 Spoke

140

35 Kph-21Mph

 

Power

Watts

Disk

183

Shamal 12 Spoke

188

Cosmic 18 Spoke

189

Citec 12 Spoke

190

Spinergy

191

HED Jet

194

Rigida 18 Spoke

194

Spengle Tri-Spoke

194

Shamal FW/36S BW

198

Corima VR/36S BW

200

Standard 36 Spoke

207

40 Kph-24Mph

 

Power

Watts

Disk

257

Shamal 12 Spoke

266

Cosmic 18 Spoke

267

Citec 12 Spoke

268

Spinergy

269

HED Jet

274

Rigida 18 Spoke

274

Spengle Tri-Spoke

274

Shamal FW/36S BW

281

Corima VR/36S BW

283

Standard 36 Spoke

293

45 Kph-27Mph

 

Power

Watts

Disk

352

Shamal 12 Spoke

364

Cosmic 18 Spoke

366

Citec 12 Spoke

367

Spinergy

369

HED Jet

375

Rigida 18 Spoke

375

Spengle Tri-Spoke

376

Shamal FW/36S BW

385

Corima VR/36S BW

388

Standard 36 Spoke

403

50 Kph-30Mph

 

Power

Watts

Disk

467

Shamal 12 Spoke

484

Cosmic 18 Spoke

487

Citec 12 Spoke

488

Spinergy

491

HED Jet

499

Rigida 18 Spoke

499

Spengle Tri-Spoke

500

Shamal FW/36S BW

513

Corima VR/36S BW

517

Standard 36 Spoke

537