Mark's Bike Shop on Hamilton Street in Normal Heights, San Diego, specializes in vintage and classic bicycles — sourcing, selling, and connecting collectors with steel-frame road and touring models from decades past. The shop operates out of a compact space one block north of Adams Avenue in the 92116 ZIP code, running a focused inventory built around the collector side of cycling rather than the new-bike retail model. Hands-on repair and mechanical service work routes through a partnership with Zumwalt's Mobile Bicycle Repair, which handles tune-ups, brake adjustments, and drivetrain overhauls at the rider's location or on-site, keeping the Hamilton Street operation focused on vintage sourcing and sales. The vintage focus covers classic steel-frame builds across eras of cycling history, running a collector discipline distinct from the new-bike retail and full-service model at Adams Avenue Bicycles, the shop established in 1978 two blocks south on Adams Avenue's main commercial corridor. Hamilton Street sits between Adams Avenue and El Cajon Blvd, Normal Heights' two primary east-west corridors, with both streets feeding cycling commuter traffic through the neighborhood on routes linking North Park to Kensington and Mission Valley beyond. Classic steel-frame bicycles occupy the same era-specific collector category as mid-century furniture and industrial design, a market served in nearby Hillcrest by Mid Century Store on the Park Blvd corridor where 1950s–1970s American and Scandinavian pieces hold steady resale value. The shop includes Wi-Fi and a gender-neutral restroom, with paid street parking along Hamilton serving walk-in traffic on its two weekly retail days. The operation concentrates vintage sourcing and collector sales into a focused weekly schedule that aligns with the estate-sale and swap-meet circuits where classic steel-frame inventory surfaces across San Diego County.