British

Sheldon Brown's Bicycle Glossary · letter B
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In the early days of bicycle manufacture, every industrialized country had its own system of thread sizes and standard dimensions for bicycle parts. The British system is the one that has, by-and-large, prevailed. British dimensions have mostly been adopted by the I.S.O. These standards include:

• 1" x 24 tpi headset thread,
• 1" (25.4 mm) handlebar/stem clamp diameter
• 1.375" x 24 tpi bottom bracket threading (left-hand on the fixed cup). This is not to be confused with Raleigh dimensions.
• 1.375" x 24 tpi freewheel thread
• 56 TPI spoke thread

Copyright © 1996, 2008 Sheldon Brown

Original: https://www.sheldonbrown.com/gloss_bo-z.html#british · Reproduced on en.wikipedalia.com with permission, all rights reserved.