Tech Talk
Wind Tunnel Testing of Aerodynamic
Bikes and Wheels Text & Photos: Editorial Dept.
82
BMU 2013 Autumn
www.biketaiwan.com
Tech Talk
I
n March of this year, Cycling Update – Wheel Giant’s consumer magazine – and the CHC cooperatively conducted Taiwan’s first wind tunnel testing of aerodynamic bicycle products. The tested products consisted of 19 aerodynamic road bikes, time trial bikes, and aerodynamic wheels. While any assessment of the overall performance of both bicycles and wheels must also take into consideration ge-
ometry, stiffness, strength, and weight, this report only focuses on aerodynamic performance, and the test data only indicates wind resistance for each product.
Testing Methodology The bicycles and wheels to be tested were mounted on CHC’s custom-built jig. Verified computational fluid dynamics (CFD) software was used to enwww.biketaiwan.com
sure that testing results expressed actual wind resistance during riding. Apart from the mounting of special devices to measure the wind resistance coefficient, a rotating platform was also used to measure wind resistance at different angles to the wind. The test wind speed was set at 30 mph (48 kph), and measurements indicated only the resistance to motion in a forward direction. Resistance coefficients were rounded 2013 Autumn BMU
83
Tech Talk
to whole numbers in grams; the greater the value, the greater the wind resistance.
Complete Bicycles The tested products in this category consisted of aerodynamic road bikes and time trial bikes. However, as bicycles are asymmetrical, measurements were performed with wind from both the right and left sides. From the perspective of someone sitting on the bike, the measurement scope extended from the center point to 15° on both right and left. One measurement was performed for each 5° turn of the rotating platform. Seven measurements were taken for each product: left 15°, 84
BMU 2013 Autumn
left 10°, left 5°, straight ahead 0°, right 5°, right 10°, and right 15°. The testing team paid close attention to any details that might affect test results. In order to insure consistency in testing, chains were placed on the largest front sprocket and smallest rear sprocket (the highest gear ratio), and the left and right cranks were placed in a horizontal position with the right crank extending forward, and no pedals were installed. Any parts that could not be adjusted were left with the factory settings during testing. For example, saddle height could not be adjusted on ISP frames, nor could the handlebar grip height be made consistent, and the different frame sizes also afwww.biketaiwan.com
fected the data.
Wheels As the front wheel of a bicycle receives the greatest wind exposure, only front wheels were tested in this project. Tire pressure was set at 100psi, and a roller was used to simulate rotation of the wheels in an unloaded condition. Because front wheels are symmetrical, the measurement scope extended from the center point to 20° on the left. One measurement was performed for each 5° turn of the rotating platform. A total of five measurements were taken in the sequence of straight ahead 0°, right 5°, right 10°, right 15°, and right 20°.
Aerodynamic Road Bikes
Tech Talk
Felt AR5
The Felt AR5 frame is made of UHC Advanced carbon fiber, and the frame geometry and tube shapes are customdesigned to easily cut through the wind. This frame allows cyclists to enjoy a rock-bottom wind resistance coefficient at an entry-level price. This frame was equipped with a Shimano 105 shift system and FSA Gossamer Pro BB386 EVO chainrings. A complete bicycle with this frame exhibited excellent handling, a high level of comfort, and the ability to easily tackle all road conditions.
Frame Shifting system Braking system Handlebars Chainwheels Freewheels Wheels Tires Saddle Dimensions Reference weight
UHC Advanced MMC carbon fiber Shimano 105 STI Shimano 105 STI Felt VS Aero 2014 double butted aluminum FSA Gossamer Pro BB386 EVO 52/36T Shimano 11-25T Felt AeroR3 Vittoria Rubino Pro Slick, 700cX23c,150tpi Prologo Zero T2.0 51, 54, 56, 58（cm） ---
Wind tunnel laboratory test data Left rotation 15˚ 1309 Left rotation 10˚ 1286 Left rotation 5˚ 1201 Front 1102 Right rotation 5˚ 1185 Right rotation 10˚ 1260 Right rotation 15˚ 1294
www.biketaiwan.com
2013 Autumn BMU
85
Tech Talk
Aerodynamic Road Bikes
Merida Reacto 909-20
The Reacto frame possesses fluid lines and amazingly low wind resistance. It nevertheless also offers ultra-high rigidity, and its distinctive DCT double-chamber carbon fiber frame tubes ensure that no pedaling energy is lost. The frame’s patented integral S-Flex flexible seat tube employs a special window-frame structure, and derives flexibility from the use of rubber and carbon compounds. In addition, an allnew 1.5” X tapered frame head tube is paired with integral Bio Flex front forks, providing precise handling and making this frame a force to be reckoned with on high-speed downhills.
Frame Shifting system Braking system Handlebars Chainwheels Freewheels Wheels Tires Saddle Dimensions Reference weight
Revo Nano Shimano Dura-Ace Shimano Dura-Ace FSA K-Force Carbon OS Shimano Dura-Ace Shimano CS-7900 11-25 SRAM S40 Vittoria Diamante Pro 23 220 Fold Selle Italia SLR XC 47, 50, 52, 54, 56, 59（cm） 7.17kg
Wind tunnel laboratory test data Left rotation 15˚ 1170 Left rotation 10˚ 1161 Left rotation 5˚ 1102 Front 998 Right rotation 5˚ 1039 Right rotation 10˚ 1163 Right rotation 15˚ 1171
86
BMU 2013 Autumn
www.biketaiwan.com
Aerodynamic Road Bikes
Ridley Noah Fast IBS
Frame Shifting system Braking system Handlebars Chainwheels Freewheels Wheels Tires Saddle Dimensions Reference weight
50, 40, 30T high modulus carbon fiber Campagnolo Record 11S Campagnolo Record 11S Deda RHM01 Rotor 3DF Campagnolo Record 11S Cole T45 Tubular Verdestein Fortezza Pro Tricomp 4ZA Cirrus Pro Team Edition XS, S, M 7.3kg
Tech Talk
The Noah Fast is Ridley’s most aerodynamic frame, and hits the sweet spot between aerodynamics and frame performance. F-Brake technology seamlessly integrates the front and rear brakes. This approach reduces overall weight and gives the frame an even more fluid appearance, and also reduces wind turbulence from the brake calipers. In addition, with Ridley’s innovative F-Splitfork design, guide openings on the front forks and seat stays absorb turbulence and stabilize the rotational inertia of the wheels. Special F-Surface wind resistance strips increase the smoothness of airflow near the frame, boosting the average speed of the bike.
Wind tunnel laboratory test data Left rotation 15˚ 1274 Left rotation 10˚ 1270 Left rotation 5˚ 1172 Front 1073 Right rotation 5˚ 1150 Right rotation 10˚ 1249 Right rotation 15˚ 1280
www.biketaiwan.com
2013 Autumn BMU
87
Tech Talk
Aerodynamic Road Bikes
Scott Foil 20
A next-generation super racing bike, the Scott Foil 20 is a perfect combination of light weight, rigidity, and aerodynamic design. All R&D, design, and manufacturing processes for the Foil were performed in the Mercedes Benz F1 wind tunnel laboratory, yielding a custom-designed bike featuring cutting-edge aerodynamic technology. The Foil 20 employs high-stiffness HMF-NET carbon fibers together with Scott’s patented integrated molding process, and a coordinated inner and outer strengthening concept enables the frame to achieve the perfect harmony and balance.
Frame
Shifting system Braking system Handlebars Chainwheels Freewheels Wheels Tires Saddle Dimensions Reference weight
HMF-NET carbon fibers & patented integrated molding process Shimano Ultegra 6700 (CT 20 speed) Shimano Ultegra 6700 Scott Road Pilot Pro OS Shimano Ultegra 6700 Shimano Ultegra 6700 Mavic Cosmic Elite Continental Ultra Race fold Scott Road Pro SL XXS, XS, S, M, L, XL, XXL 7.40 kg
Wind tunnel laboratory test data Left rotation 15˚ 1118 Left rotation 10˚ 1073 Left rotation 5˚ 1051 Front 1002 Right rotation 5˚ 1030 Right rotation 10˚ 1066 Right rotation 15˚ 1096
88
BMU 2013 Autumn
www.biketaiwan.com
Time Trial Bikes
Tech Talk
Argon 18 E-118
The Argon E-118 features a 7105HM carbon fiber frame, ONEness 2.0 integral front forks, and time trial handlebars. It achieves optimal low wind resistance through the use of hidden brake calipers and aerodynamic calculations adapted from F1 racing car design. The bike’s unique AFS-Tri triathlon frame geometry features a low bottom bracket height, which lowers the bike’s center of gravity and increases high-speed cornering stability. The carbon fiber ASP-7500 dual-angle seatpost and AHB-7500 handlebars ensure that riders can assume an ideal racing posture. The bottom bracket specifications are BB86, and the frame is compatible with a Di2 shift system.
Frame Shifting system Braking system Handlebars Chainwheels Freewheels Wheels Tires Saddle Dimensions Reference weight
carbon fiber SRAM Force TRP disc brakes E118 ONEness 2.0 Vision TriMAX Carbon SRAM PG1070 Vision Metron 81 Vittoria Corsa EVO CX Aspide TT XS, S, M, L frame 1,225g（M） front fork 545g
Wind tunnel laboratory test data Left rotation 15˚ 876 Left rotation 10˚ 911 Left rotation 5˚ 981 Front 938 Right rotation 5˚ 971 Right rotation 10˚ 929 Right rotation 15˚ 908
www.biketaiwan.com
2013 Autumn BMU
89
Tech Talk
Time Trial Bikes
Aster ATT
The Aster ATT employs high-modulus carbon fiber composite, and its design features a hidden conical headset and hidden cables. And on top of its high-performance design, the ATT also boasts attractively streamlined styling: the knife-blade tubing profile reduces the frame’s frontal area, and performance has been verified via aerodynamic testing. The ATT pairs low wind resistance with a lightweight structural design, while making sure that cyclists enjoy high rigidity and optimum torque while riding.
Frame Shifting system Braking system Handlebars Chainwheels Freewheels Wheels Tires Saddle Dimensions Reference weight
high-modulus SRAM New Red SRAM New Red Aster carbon fiber SRAM New Red 50/34 SRAM New Red 11-28T Aster T85 Tufo CS33 Pro Aster AP1 47, 49, 52（cm） 7.38kg
Wind tunnel laboratory test data Left rotation 15˚ 1023 Left rotation 10˚ 1026 Left rotation 5˚ 1000 Front 960 Right rotation 5˚ 1008 Right rotation 10˚ 1024 Right rotation 15˚ 1044
90
BMU 2013 Autumn
www.biketaiwan.com
Time Trial Bikes
Tech Talk
Kuota Kalibur
The Kalibur is Kuota’s flagship time trial bike. This year’s version incorporates some all-new technology, including routing of air flow from the seat post through the rear wheel, diversion around the seat clamp to reduce eddy flow in the rear, and use of a low-drag head tube and KIC hidden cables. These measures ensure that the frame has sharply reduced air resistance. The HPT high-strength bottom bracket has PF30 specifications, and is compatible with either a Di2 electronic shift system or mechanical shift system.
Frame Shifting system Braking system Handlebars Chainwheels Freewheels Wheels Tires Saddle Dimensions Reference weight
Kuota Kalibur SRAM Red SRAM Red Vision TriMax Carbon Si Vision TriMAX Carbon SRAM OG1090 Vision Metron 90 / Metron Disc Vittoria Corsa EVO CX Aspide TT XS, S, M, L frame 1,320g（S） front fork 350g
Wind tunnel laboratory test data Left rotation 15˚ 803 Left rotation 10˚ 843 Left rotation 5˚ 879 Front 905 Right rotation 5˚ 913 Right rotation 10˚ 883 Right rotation 15˚ 841
www.biketaiwan.com
2013 Autumn BMU
91
Tech Talk
Time Trial Bikes
Ridley Bikes Dean ISP
Ridley was pioneer in applying aerodynamic concepts to time trial frames, and has applied its proprietary F-Surface and FSplitfork aerodynamic technologies to the Dean ISP frame. The F-Splitfork technology relies on a split front fork and seat stay design to reduce air holdup caused by the spokes of the turning wheels. Specialized F-Surface wind resistance strips increase the smoothness of airflow near the frame, which boosts the average speed of the bike. The frame also employs a tapered head tube that is 1-1/8” at the top and 1-1/2” at the bottom, which resolves the problem of instability caused by a short head tube in time trial bikes. There are 76°/78° saddle angle options, and riders can chose the angle that suits them best when riding or racing.
Frame Shifting system Braking system Handlebars Chainwheels Freewheels Wheels Tires Saddle Dimensions Reference weight
50, 40, 30T High modulus carbon fiber Shimano Ultegra 6700 Deda TT Brakes 3T Aura Pro Rotor 3DF Shimano Ultegra 6700 Cole T85 Verdestein Fortezza Pro Tricomp Selle San Marco Ponza TT XS, S, M 8.2kg
Wind tunnel laboratory test data Left rotation 15˚ 1080 Left rotation 10˚ 1108 Left rotation 5˚ 1065 Front 1006 Right rotation 5˚ 1024 Right rotation 10˚ 1076 Right rotation 15˚ 1064
92
BMU 2013 Autumn
www.biketaiwan.com
Time Trial Bikes
Tech Talk
Swift Neurogen
The Swift Neurogen is manufactured using high-coefficient T1000 and M40 carbon fiber material, accompanied by a special carbon fiber stacking method, and has minimal paint and printing in order to eliminate as much weight as possible. The frame is stable, rigid, and responsive, while complying with UCI regulations. The down tube, seat tube, and seat stay geometry have been designed based on NACA airfoil sections, and the use of an even larger angle reduces drag. The ultra-long 160 mm head tube and hidden brake system also yield significant aerodynamic benefits, and the shape of the seat tube is harmonized with the rear wheel to effectively control air flow.
Frame Shifting system Braking system Handlebars Chainwheels Freewheels Wheels Tires Saddle Dimensions Reference weight
SwiftCarbon Neurogen SRAM Red SRAM Red Vision SRAM Red SRAM Red SwiftCarbon Hemoglobin Vittoria SwiftCarbon XS, S, M, L 7.7kg
Wind tunnel laboratory test data Left rotation 15˚ 826 Left rotation 10˚ 824 Left rotation 5˚ 891 Front 893 Right rotation 5˚ 899 Right rotation 10˚ 870 Right rotation 15˚ 846
www.biketaiwan.com
2013 Autumn BMU
93
Tech Talk Wheels
Campagnolo Bora Ultra Two
Campagnolo’s ultra-high-end Bora Ultra Two wheels are favorites of professional riders and amateur cyclists alike. The wheels utilize USB (Ultra Smooth Bearings), optimized ceramic ball bearings that can cut weight by 30% and increase stiffness by 40% compared to other Campagnolo bearings. CULT (Ceramic Ultimate Level Technology) gives the wheels high corrosion resistance while providing an excellent lubricating effect and feeling of smoothness.
Applicable shift system Rim height (front, rear) Rim width (front, rear) Spoke number (front, rear) Hub type Spoke type Nipple Weight
94
BMU 2013 Autumn
Campagnolo、Shimano 50/50（mm） 20/20（mm） 18/21 Carbon fiber Stainless steel aluminum alloy 1,310g
www.biketaiwan.com
Wind tunnel laboratory test data Front 355 Right rotation 5˚ 378 Right rotation 10˚ 381 Right rotation 15˚ 372 Right rotation 20˚ 382
Wheels
FFWD F4R-C
Applicable shift system Shimano（10s, 11s） Campagnolo（10, 11s） Rim height (front, rear) 38/38（mm） Rim width (front, rear) 20/20（mm） Spoke number 20/24 (front, rear) Hub type DT Swiss-DT 240S´ Spoke type DT Swiss-DT Aerolite Nipple DT Pro Lock Brass Weight 1,630g
Wind tunnel laboratory test data Front Right rotation 5˚ Right rotation 10˚ Right rotation 15˚ Right rotation 20˚
329 358 373 365 377
Tech Talk
FFWD is a new Dutch brand specializing in carbon fiber wheels for high-end racing bikes. All FFWD wheels are produced and painted by hand at the well-known Dutch assembly plant Zoran, and all bear manufacturer’s serial numbers symbolizing their uniqueness. The F4R-C is designed for climbing and multifunctional use. The wheels are made using TC35 reinforced high-tensile carbon fiber material providing extraordinary rigidity. The surface fabric layer is 3K carbon fiber with excellent compressive strength, and the braking surfaces are considerately designed. The wheels come with inner flaps and extended valves and wheel bags, and the manufacturer provides a two-year warranty.
www.biketaiwan.com
2013 Autumn BMU
95
Tech Talk
Wheels
Fulcrum Racing Speed XLR
Fulcrum’s Racing Speed XLR wheels feature hubs with carbon fiber spindles and aluminum alloy flanges for optimum light weight. The diameter of the ratchet base has been increased to 78 mm, enhancing acceleration performance. Unique CULT technology employs high-grade ceramic ball bearings that boost rigidity by 40% and cut weight by 30%, and also provide a pleasing sense of smoothness and high corrosion resistance. Fulcrum has specially developed a proprietary composite material for the rims, which resolves the long-term problem of the braking surface on carbon fiber wheels. These wheels have as good braking performance as aluminum alloy wheels. When wet, it only takes one rotation to clear the water from the braking surface before the brakes take hold. Applicable shift system Shimano, SRAM, Campagnolo Rim height (front, rear) 50/50（mm） Rim width (front, rear) 20.5/20.5（mm） Spoke number 18/21 (front, rear) Hub type Carbon fiber/ aluminum alloy Spoke type Stainless steel Nipple Mo Mag patent Weight 1,324g
96
BMU 2013 Autumn
www.biketaiwan.com
Wind tunnel laboratory test data Front 355 Right rotation 5˚ 362 Right rotation 10˚ 372 Right rotation 15˚ 353 Right rotation 20˚ 361
Wheels
Tech Talk
Mega ITC
(Inertial Tubeless Carbon)
These 23mm are designed to be used with 23C tubeless tires. The tires fit the rims perfectly, with minimal gap. The distance between the rims gradually increases from 23mm to 24.6mm, achieving an excellent wind-shedding effect. The spokes are mounted on the two sides of the rims, and act as brake discs. The right and left spokes do not interfere with each other’s air diversion effect, and are nearly impervious to side winds. The spokes are pulled outward from inside in a pattern centered on the drive points, enabling direct drive of the largest rim diameter. The structure of each force-bearing point is an inertial flinging point. This sharply increases inertia and instantaneous acceleration while effectively lowering wind resistance.
Applicable shift system Rim height (front, rear) Rim width (front, rear) Spoke number (front, rear) Hub type Spoke type Nipple Weight
9/10/11 58/58（mm） 23/23（mm） 20/24 Mega R20/R24 1422 flat flat head HEX-12 + Stainless steel washer 1,630g
www.biketaiwan.com
Wind tunnel laboratory test data Front 329 Right rotation 5˚ 307 Right rotation 10˚ 287 Right rotation 15˚ 314 Right rotation 20˚ 320
2013 Autumn BMU
97
Tech Talk
Wheels
Reynolds 72 Aero
Applicable shift system Campagnolo（10/11s）, Shimano（10/11s） Rim height (front, rear) 72/72（mm） Rim width (front, rear) 26.2/26.2（mm） Spoke number 16/20 (front, rear) Hub type Reynolds（front）/ DT Swiss（rear） Spoke type DT Swiss Nipple Reynolds hidden Weight 1,608g
Wind tunnel laboratory test data Front Right rotation 5˚ Right rotation 10˚ Right rotation 15˚ Right rotation 20˚
98
BMU 2013 Autumn
302 299 267 335 342
Reynolds’ 2013 Aero series wheels were designed with DET aerodynamic technology and CTG braking technology, and feature DT Swiss straight-pull hubs and ultra-light carbon fiber rims. The DET concept inherits the V-shaped rim design of the RZR series, and can effectively cut drag while significantly improving steering. The extrawide 26.2 mm rims provide outstanding handling and stability, and have superb lateral rigidity. As a result, the wheels are easy to control in a side wind. CTG braking technology significantly decreases brake temperature, reducing hightemperature deformation when the company’s proprietary blue brake blocks are used, to provide smooth and reliable braking performance. www.biketaiwan.com
Wheels
Rolf-Prima TDF6SL
Tech Talk
The all-new design of Rolf-Prima’s TDF6SL wheels includes an even wider rim profile and a brand-new shape. This not only increases tire contact area, but also yields even better aerodynamic characteristics, minimizing the wind resistance coefficient and ensuring that a side wind poses no problems for the 60 mm-high rims. In addition to high-strength CNC hub shells made by America’s White Industries, the wheels also boast titanium alloy ratchet bases. The small number of high-tension Sapim flat spokes used in the wheels provides outstanding lateral and forward stiffness. The carbon fiber weave is denser on the braking surfaces, ensuring durability and good braking performance. These wheels are only available in a tubular version, and meet UCI and ITU usage standards.
Applicable shift system Shimano（8-11s）, Campagnolo（11s） Rim height (front, rear) 60/60（mm） Rim width (front, rear) 23/23（mm） Spoke number 16/16 (front, rear) Hub type TDF5.5 ceramic bearings, titanium alloy ratchet Spoke type Sapim CX-RAY Nipple Sapim Weight 1,435g
www.biketaiwan.com
Wind tunnel laboratory test data Front 304 Right rotation 5˚ 286 Right rotation 10˚ 318 Right rotation 15˚ 315 Right rotation 20˚ 322
2013 Autumn BMU
99
Tech Talk
Wheels
Shimano WH-9000-C50-CL
These carbon fiber inner tube-type wheels employ Shimano’s patented carbon fiber manufacturing technology. The D2 rim design delivers good aerodynamics and stability, and the OptBal spoke system ensures rigidity and durability. The recessed copper spoke heads improve aerodynamics and give the wheels a streamlined appearance, and the extra-wide hub flanges increase lateral stiffness. The titanium ratchet base provides high strength and light weight. The simple bearing adjustment ensures smooth power transmission. Shimano’s track-type ball bearings and ultra-large 7075 alloy axles offer a high level smoothness.
Applicable shift system Rim height (front, rear) Rim width (front, rear) Spoke number (front, rear) Hub type Spoke type Nipple Weight
100
BMU 2013 Autumn
Dura-Ace 9000 50/50（mm） 23/23（mm） 16/21 high strength light weight titanium ratchet 2.0-1.8-2.0/Bladed aluminum alloy 1,672g
www.biketaiwan.com
Wind tunnel laboratory test data Front 315 Right rotation 5˚ 305 Right rotation 10˚ 353 Right rotation 15˚ 336 Right rotation 20˚ 338
Wheels
Tech Talk
Trigon CW02
These Trigon rims are 45m m high, and the wheels provide exceptional rigidity and ultra-low wind resistance. In addition, the relatively low tire pressure reduces the chance of a blowout, while providing riders with a high degree of cornering stability and allround riding excitement. The carbon fiber hubs have a precision positioning design maintaining the tension of each carbon fiber spoke. The transmission of force to these wheels feels instantaneous, enabling cyclists to maintain an even cadence and high degree of sensitivity on even challenging curving roads and climbs.
Applicable shift system Rim height (front, rear) Rim width (front, rear) Spoke number (front, rear) Hub type Spoke type Nipple Weight
Shimano, Campagnolo 45/25（mm） 45/25（mm） 12/18 Carbon fiber Carbon fiber No Nipple 1,300g
www.biketaiwan.com
Wind tunnel laboratory test data Front 369 Right rotation 5˚ 358 Right rotation 10˚ 357 Right rotation 15˚ 386 Right rotation 20˚ 387
2013 Autumn BMU
101
Tech Talk
Wheels
Vision Metron81
Vision’s all-carbon fiber wheels take tubular tires with a width of 20-25mm. The wheels feature Metron ceramic bearing hubs made by Vision, and the optimized wheel structure increases strength. The bearings have a pre-loaded, adjustable design. Vision’s redesign of the wheels with a wide rim geometry and Ushaped cross-section can ease surface turbulence and achieve the goal of lower drag. Finally, Vision’s QR-89 carbon fiber quick releases ensure an ever lighter overall weight.
Applicable shift system Shimano（10/11s） Campagnolo（10/11s） Rim height (front, rear) 81/81（mm） Rim width (front, rear) 24.5/24.5（mm） Spoke number 18/21 (front, rear) Hub type Vision Metron Spoke type light weight bladed Nipple ABS Weight 1,590g
102
BMU 2013 Autumn
www.biketaiwan.com
Wind tunnel laboratory test data Front 325 Right rotation 5˚ 305 Right rotation 10˚ 270 Right rotation 15˚ 330 Right rotation 20˚ 346
Wheels
Tech Talk
ZIPP 404
When Zipp developed and designed its FireCrest Tubular wheels, it used a laser scanner in order to design an optimal tire bed. In addition to reducing tire rolling resistance and improving cornering performance, this design ensures that even worn-out tires sit securely in the tire bed. These wheels also feature Zipp’s all-new Carbon Bridge structure, which employs an “inner frame” reinforcing structure, and relies on a large rim edge curvature to shift external strength to the rim sidewalls. At the same time, a greater thickness of material is used in side impact areas to boost overall strength. The rear wheel is paired with a 188 hub. The bearings on the non-drive side extend outward 7.5mm, and the slightly inward-pointing spoke angle increases stiffness. These wheels offer the sturdiness needed for classic races, and the comfort needed for long-distance riding.
Applicable shift system Shimano, SRAM, Campagnolo Rim height (front, rear) 58/58（mm） Rim width (front, rear) 27.5/27.5（mm） Spoke number 16/20 (front, rear) Hub type 88/188 Spoke type Sapim CX-RAY Nipple Sapim Weight 1,355g
www.biketaiwan.com
Wind tunnel laboratory test data Front 315 Right rotation 5˚ 305 Right rotation 10˚ 277 Right rotation 15˚ 294 Right rotation 20˚ 311
2013 Autumn BMU
103
