Yasujiro Creates History with 5.42kg Steel Road Bike
Yasujiro has achieved a significant engineering
milestone by developing a steel road bike weighing only 5.42kg, currently the lightest in its category. Unveiled at the 2019 Eurobike show, this frame utilizes the complete Tange Ultimate chromoly tubeset, which provides an optimal strength-to-weight ratio while maintaining the characteristic ride qualities of steel.
The frame’s technical specifications include a standard 1-1/8″ head tube, BSA bottom bracket shell, and brake reach of 39-49mm. Additionally, the bike features the Yasujiro signature wishbone back stay design, which contributes to frame rigidity while reducing overall weight. This frame is sold as a complete kit that includes the frame, matching Tange Prestige CrMo fork, and Be King headset.
From a construction perspective, the tubing selection and butting profiles have been carefully optimized to remove excess material while preserving structural integrity. The connections between tubes demonstrate precise manufacturing tolerances, particularly at the wishbone junction where weight reduction is most critical.
Weight distribution analysis shows that the frameset benefits from strategic material placement, with thinner tube walls in low-stress areas and reinforced sections where structural demands are highest. Furthermore, the frame geometry maintains optimal handling characteristics despite the extreme weight reduction measures.
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The 5.42kg total weight specification represents a fully built bicycle that includes premium components such as the Campagnolo Super Record groupset, Bora Ultra Tubular wheels, and 3T carbon handlebars. However, the frame itself demonstrates that modern steel fabrication techniques can produce results comparable to alternative frame materials when pushed to technical limits.
Frame Construction: Tange Ultimate and Premium Materials
The Yasujiro frame utilizes the full Tange Ultimate chromoly tubeset, which consequently provides an exceptional strength-to-weight ratio. First of all, this premium steel composition contains precise amounts of chromium and molybdenum that therefore enhance tensile strength while maintaining weldability. Additionally, the tube walls feature variable thickness through butting techniques, where thicker sections exist at stress points like joints, whereas thinner sections appear in lower-stress areas.
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Moreover, the frame construction incorporates several technical features including a standard 1-1/8″ head tube and BSA bottom bracket shell. Furthermore, Yasujiro engineers designed the distinctive wishbone back stay using specialized tube forming processes to both reduce weight and increase vertical compliance. Meanwhile, the brake bridge accommodates calipers with 39-49mm reach, thus providing compatibility with modern brake systems.
The tubing selection process involves precise diameter calculations that subsequently determine ride characteristics. In particular, the down tube and chain stays utilize larger diameters for increased stiffness, while the seat stays and top tube employ narrower profiles to promote comfort. Additionally, the frame joints display clean welds with minimal material buildup, which consequently reduces overall weight.
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Because of material selection and engineering, the Yasujiro frameset achieves remarkable weight metrics without compromising durability. The complete tubeset undergoes heat treatment processes that furthermore enhance strength properties. Finally, the frame arrives as part of a kit including a matched Tange Prestige CrMo fork that similarly balances lightweight construction with performance characteristics.
Component Selection: Why Campagnolo Super Record?
The Yasujiro 5.42kg steel road bike exclusively features Campagnolo Super Record components, which consequently contributes to both the bike’s minimal weight and premium performance profile. First of all, the Super Record groupset represents Campagnolo’s flagship product line and therefore offers the lightest mechanical shifting system in their catalog. Additionally, the carbon fiber construction of shifters, derailleurs, and brake levers significantly reduces weight compared to aluminum alternatives.
Moreover, the Super Record Ultra Torque titanium crankset with 53/39 chainrings provides an optimal balance between stiffness and lightweight construction. Furthermore, the titanium hardware throughout the groupset shaves grams while maintaining durability standards. Meanwhile, the 11-speed cassette with 12-29 tooth range delivers both high-speed capability and comfortable climbing ratios.
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The brake calipers similarly utilize carbon fiber components and titanium hardware, thus creating a high-performance stopping system without excess weight. Additionally, the entire Super Record groupset offers precise Italian manufacturing tolerances that consequently reduce friction and improve mechanical efficiency.
Systems Work Seemlessly Together
Because Yasujiro engineers chose the complete Super Record package, the bike maintains component integration throughout the drivetrain. Furthermore, the shifters, derailleurs, and braking systems work seamlessly together due to matching cable pull ratios and mechanical design. Finally, the aesthetic cohesion between the polished silver components and the steel frame creates a visually harmonious build while the lightweight materials complement the engineering goals of producing an exceptionally light yet functional steel bicycle.
Wheel System: Bora Ultra Tubular and Continental Competition
The Yasujiro ultralight road bike incorporates Campagnolo Bora Ultra Tubular wheels, which consequently play a critical role in achieving the 5.42kg total weight. First of all, these high-performance wheels feature full carbon fiber construction including rims, spokes, and hub shells. Additionally, the tubular rim design eliminates the need for conventional clincher beads and thus reduces overall rim mass significantly.
Moreover, the carbon fiber spokes provide substantial weight savings compared to traditional steel spokes while maintaining lateral stiffness. Furthermore, the ceramic bearings within the hubs decrease rotational friction and subsequently improve efficiency during both acceleration and sustained speeds. Meanwhile, the aerodynamic rim profile reduces wind resistance despite the emphasis on lightweight construction.
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The wheel system uses Continental Competition tubular tires in 700×22c. This balances minimal rolling resistance with adequate road grip. The tubular construction method bonds the tire directly to the rim, thus eliminating the need for heavy inner tubes. Because tubular systems use lightweight latex inner tubes sewn into the tire casing, the complete wheel setup achieves minimum weight targets.
Bora Ultra Wheelset: Optimal Torque Transfer
Furthermore, the Bora Ultra wheelset features Campagnolo’s G3 spoke pattern that subsequently provides optimal torque transfer during acceleration. Additionally, the front and rear hubs maintain compatibility with the Super Record 11-speed cassette system. Finally, the complete Yasujiro wheel system demonstrates how carefully selected cycling components contribute to both weight reduction and performance enhancement through technological integration and material selection.
Premium Finishing Components: Carbon Seatpost, Brooks C13 Saddle, and Ritchey WCS Cockpit
The Yasujiro 5.42kg steel bike has carefully selected finishing components. These components reduce weight and improve rider comfort. The 27.2mm carbon fiber seatpost saves weight over aluminum. It also offers vibration damping. The carbon layup pattern increases vertical compliance. This improves comfort on long rides without losing power transfer.
Moreover, the Brooks C13 saddle represents a modern interpretation of classic saddle design, thus balancing minimal weight with ergonomic support. Furthermore, the C13 features a carbon fiber shell and rails that subsequently reduce mass compared to traditional steel-railed models. Meanwhile, the weatherproof top material eliminates unnecessary weight from traditional leather while maintaining durability standards.
Lightweight & High-Performance Bike Cockpit: Ritchey WCS Stem & 3T Carbon Bars
The cockpit components include a Ritchey WCS aluminum stem and 3T carbon fiber handlebars. This creates a lightweight front-end interface. The Ritchey WCS stem uses 7075 aluminum alloy. This alloy offers a superior strength-to-weight ratio compared to conventional 6061 alloys. Handlebar position affects comfort and control. The 3T carbon bars provide multiple hand positions while maintaining minimal weight
Furthermore, the carbon fiber construction of the handlebars absorbs road vibration before it reaches the rider’s hands. Finally, these premium contact points complete the Yasujiro build by maintaining the ultralight design philosophy throughout every component while ensuring rider comfort remains a priority alongside weight reduction goals.
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