Servicing threaded headsets

by Raymond Parker on August 18, 2012

in Technical

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1″ Threaded Headset

Most new bicycles come fitted with threadless headsets. They have advantages: They are stiff, make changing handlebars and stems a snap and adjustment is generally straightforward.

However, classic threaded steering assemblies allow simple raising of the handlebars, by loosening the binder bolt running through the stem and into the fork steerer tube. They are time-tested and reliable, with simple maintenance.

If you are restoring a vintage bike or prefer to outfit your classic retro-randonneuse with the appropriate parts, here’s a guide to maintaining and adjusting a standard ball-bearing steering mechanism.

This tutorial covers the basics, assuming a minimum tool set. Replacement of major components requires specialized and expensive tools.

Tools & Supplies

  • Adjustable wrench and/or appropriate headset wrenches
  • Vice grips (if adjustable race is not “nutted”)
  • Wrench or allen key (to remove handlebar stem)
  • Bearings
  • Grease
  • Rags
  • Img description

    Threaded Headset Tools

    Dismantling the Headset

    • Loosen the (uppermost) locknut, using adjustable or appropriate wrench (usually 32mm). If necessary, immobilize top bearing race with second wrench.
    • Remove spacers
    • Unscrew and remove top bearing race
    • Slide out fork
    • Remove bearings from both top and bottom fixed races (some will have loose bearings, some in a clip)
    • Clean parts thoroughly and examine for wear. Replace bearings if dull and crown race if pitted (puller required). If fixed cups are severely pitted, best replace the whole headset–a procedure beyond the scope of this tutorial.

      Headset Assembly

      • Turn bicycle frame upside-down
      • Apply grease to lower pressed race
      • Press bearings into place and coat with another bead of grease
      • Insert forks
      • Hold forks in place while returning frame to upright position
      • Apply grease to upper pressed race
      • Press bearings into place and coat with another bead of grease
      • Replace spacers, aligning tabs with groove in rear of steerer tube, if applicable
      • Grease threads and re-install lock nut.

      Headset Adjustment

      • Adjust threaded top race until forks rotate smoothly
      • Immobilize top race with appropriate wrench or vice-grip
      • Tighten down lock nut
      • Recheck movement of forks. Re-adjust if loose or binding
      • Install wheels and front brake on frame
      • Apply brake and rock bike back and forth. If play is felt in headset, re-adjust.

      Threaded Headset Sizes

      Steerer Size Outside diameter Inside steerer/ Stem diameter Crown race Inside diameter Frame Cup Outside diameter Threads Per inch Notes
      BMX .833″ (21.15mm) 26.4mm 32.7mm 24 Used mainly on bikes with one-piece cranks & early mountain bikes.
      French 25mm 22mm 26.5mm 27.0mm 30.2mm 25.4(1 mm) Obsolete. French steerers usually flat filed on the rear, rather than grooved.
      1″ Standard (25.4mm) 7/8″ (22.2mm) 26.4mm 30.2mm 24 Standard 1″
      1″ Italian (25.4mm) 7/8″ (22.2mm) 26.5 mm 27.0mm 30.2mm 24 Obsolete. Threads cut at 55 deg. ISO or J.I.S. headsets may be substituted
      1″ J.I.S.(25.4mm) 7/8″ (22.2mm) 27.0mm 30.0mm 24 Older lower-quality bicycles from Asia
      1″ Raleigh(25.4mm) 7/8″ (22.2 mm) 26.4mm 30.2mm 26 Found on Raleigh bicycles made in Nottingham, UK
      Austrian(26 mm) 22mm 26.7mm 30.8mm 25.4(1mm) High quality Austrian bikes use English/ISO
      French Tandem 28mm 22mm 25.4(1mm) Rare
      1 1/8″(28.6mm) 1″ (25.4mm) 30.0mm 34.0mm 26 “Oversized” (Found on older MTBs, more often  threadless size)
      1 1/4″(31.8mm) 1 1/8″ (28.6mm) 33.0mm 37.0mm 26 Tandem standard

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