Updated 20th March 2026

Technical Specifications & Geometry (1979–1984)

Serial numbers tell you when a frame was fabridated, but the physical characteristics tell you what it is. This guide helps you distinguish between a Silver Streak, a Pro Senior, and a Harry Leary Turbo based on factory specs.

The "2mm vs 3mm" Rule

One of the most common points of confusion is dropout thickness. Generally, "Pro" level racing frames utilized 2mm dropouts to save weight, while "Street" or entry-level models like the Silver Streak, Viper and TK used heavier 3mm dropouts for durability. There were also material variations too

Model-by-Model Reference Table

See below

Key Identification Markers:

The Looptail: A signature of the 1979–1983 Pro and Silver Streak models.

The Gusset: Large gussets are typical of the TK and early Pro models, while a "Small Diamond Gusset" is a hallmark of the 3rd Gen HLT and Formula One.

Bottom Brackets: High-end race models often utilized Euro BBs, while most standard models used US BBs.