The Raleigh Twenty uses a mixture of ISO (standard) and proprietary (non-standard) parts. Here is some technical information and suggestions which can help you maintain and/or upgrade your Raleigh Twenty.
- 76mm wide shell. Raleigh proprietary threading (26tpi whereas ISO is 24tpi)
- Narrow Spacing (90mm) and Raleigh Threading (26tpi Raleigh Proprietary).
- The rear triangle is spaced at 114mm to accept Sturmey-Archer AW hubs.
- 28.6mm diameter, chromed steel
- ISO 451mm or ISO 406mm, typically 28-spoke steel rims.
(See my article outlining these two wheel sizes)
Hubs and Gearing
- Single speed with coaster brake
- 3-speed (Usually Sturmey-Archer AW, but sometimes AG dynohub)
- New-Zealand built versions offered a 2-speed "duomatic" rear hub with coaster brake.
- Some versions have Shimano 3-speed hubs.
- 46-tooth Chain-wheel and 15-tooth sprocket, giving gears of approx. 46 - 61 - 83 gear inches.
- Standard Raleigh Brakes on ISO 451mm-wheeled versions
- Weinmann Long Reach Callipers on ISO 406mm-wheeled versions
- There appears to be three main types of handlebar used on production Twentys
1.) One-piece "All-rounder" bars.
2.) Two-piece "All-rounder" bars.
3.) Two-piece "North-Road" bars.
The "All-rounder" style is similar to modern MTB Riser bars, but with considerably more rise. The "North Road" type have a more generous back-sweep on the grips, similar to what many dragster bicycles later used, but with less rise than dragster bars.
All production handlebars were held on by a clamp around the top of the forks, and the stems do not have binder bolts.
Please note: The stem has a height-limiter in the form of a loop of stiff wire which runs around the front brake bolt. To remove the handlebar and stem from the frame, you must first remove the front brake.