Diamond Back Formula One

Diamond Back Formula 1 – 1984 Catalogue

Diamond Back Formula 1 Specifications

FinishChrome with chrome and Turbo Smoke anodized components.
FrameDiamond Back Formula One, chrome-moly. ( Koizumi )
ForkDiamond Back Formula One, chrome-moly. ( Koizumi )
HandlebarsDiamond Back Formula One, chrome-moly. ( Koizumi )
GripsTaiwan Oakley B-1B copies
HeadsetTange MTX
StemDiamond Back Formula One aluminium and chrome-moly shaft
RimsAraya 7XN, 20×1.50, Chrome, aluminium.
Spokes36 .080/060/080.
HubsSuzue, aluminium, low-flange.
Brake calipersDia-Compe.
Brake leversDia-Compe Tech 3
Brake padsDia-Compe
TiresFront; Mitsuboshi Comp Ill, rear; Turbo Lite by Mitsuboshi.
PedalsSunTour XC-Il, aluminium and chrome-moly.
CranksSugino CT, three-piece forged chrome-moly 175mm
Bottom BracketSugino with Sugino chrome-moly spindle.
Front SprocketSugino aluminium chainwheel, 44 teeth Integral with pedal arm.
Rear SprocketSunTour, 16 teeth.
ChainD.I.D., 3/32 inch
SeatDiamond Back 5-Gold (Kashimax)
Seat PostFormula One, aluminium.
Seat Post ClampSakae-Ringyo (SR) aluminium

Identifying characteristics

The Diamond Back Formula 1 is a Koizumi made frame and forks. The production run was from late 1983 until 1984. It was one of the last Diamond Back BMXs to be produced by Koizumi, alongside the 1984 Harry Leary Turbo.

The model is identified by some distinctive characteristics. Like the Silver Streak, it is small compared to the pro models and was aimed at an age group range of 10 – 14 years, it size and high-quality components ensured it was extremely light – the entire bike weighing in at 21lbs (9.5kg). The frame is a stick tail, meaning each rear stay is constructed out of two tubes, instead of one continuous piece in a looptail, the rear drop outs have a unique diamond cutout.

Formula 1 “Bat-wing” brake bridge

Other interesting design features are the rear brake bridge, which has a distinctive ‘bat wing’ style design, which is also shared by the 1984 Harry Leary Turbo.

Identifying characteristics/things to look out for include:

  • serial number beginning with either a 3 or 4, meaning 1983 and 1984
  • Distinctive ‘bat-wing’ rear brake bridge
  • Small gusset (two TIG welds)
  • Slightly shorter forks (by 1″) than all other models of the same period
  • Stick tail
  • Diamond cut out on rear dropouts as well as forks
Diamond Back Formula 1 Advert 1983