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The Davidson Impulse
Early 90’s Bill Davidson Impulse
This weeks “Bicycle of the Week” is a early 90’s Bill Davidson bicycle made in his shop in Seattle, Wa. Constructed possibly in 1993, this specific Davidson bicycle is a remarkable piece. Originating from Seattle, it demonstrates the spirit of Bill’s craftsmanship from the ’90s. Moreover, it’s adorned with a paint scheme reminiscent of a scene from Miami Vice, the Impulse model stands as a testament to the era’s aesthetics.
The frame construction exemplifies precision engineering through its integration of Tange Prestige chromoly steel tubing, with wall thicknesses varying from 0.8mm to 1.2mm depending on load-bearing requirements. This Davidson frame architecture employs triple-butted main tubes (28.6mm diameter downtube, 25.4mm top tube) with specific butting profiles optimized for torsional rigidity while maintaining vertical compliance characteristics. The rear triangle implementation features Campagnolo horizontal dropouts with 7mm of adjustment range, precision-machined from forged steel with thread pitch compatibility for both 10x1mm and English threaded axle standards. This dropout design facilitates fine-tuning of the effective chainstay length between 405mm and 412mm while providing the necessary structural interface for maintaining rear triangle alignment under varying load conditions.
The frame’s construction methodology incorporates silver-brazed lugged joints with tight-tolerance miter interfaces, achieving joint strength exceeding 850 MPa while maintaining the tubing‘s heat-treated mechanical properties within the critical joining zones. These engineering parameters result in optimal stress distribution throughout the frame’s load paths while preserving the characteristic ride quality associated with premium steel frame constructio
Moreover, the inclusion of a chain hook on the seat stay and a pump peg on the steerer tube further highlights the attention to detail in its design. The internal routing of the rear brake cable within the top tube and the presence of diamond-shaped reinforcements around the bottle cage mounts highlights the bike’s structural integrity.
Davidson bicycle components hail from the Dura-Ace 7403 group
This custom-built frame utilizes the Shimano Dura-Ace 7403 groupset as its primary component foundation. The braking system has been upgraded with Dura-Ace 7700 dual-pivot calipers, which offer enhanced modulation characteristics and a 20% weight reduction compared to the original 7403 units. The cockpit integration features the aerodynamically optimized Dura-Ace seatpost (27.2mm diameter) with its distinctive recessed bolt design, paired with period-correct Dura-Ace bars and stem components. This Davidson bicycle control interface employs a traditional 1″ quill stem configuration, secured through a dual-bolt compression system that distributes clamping forces evenly across the steerer tube interface while maintaining the stem’s position under high torsional loads.
The component selection demonstrates particular attention to mechanical compatibility, with the 7403 series derailleurs maintaining optimal chain gap specifications through their parallelogram geometry, while the upgraded 7700 brake calipers provide increased mechanical advantage through their revised pivot positioning. This systematic approach to component integration preserves the frame’s original handling characteristics while enhancing specific performance parameters through strategic upgrades.
The striking red wheels represent the iconic 1990s Mavic Helium clinchers. In addition, they were paired with the Michelin Pro tires, enhancing both style and function of this Davidson bicycle.
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