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 this article outlining these two wheel sizes)
Ball Bearings for the Original Configuration Raleigh Twenty
- The standard Sturmey-Archer front hub (not a Dyno-Hub) has twn (10) 3/16 inch Ball Bearings on each side for a total of twenty (20) balls.
- The Bottom Bracket has eleven (11) 1/4 inch Ball Bearings on each side for a total of twenty- two (22) balls.
- The bearing at the bottom of the Head Tube has twenty-five (25) 5/32 inch Ball Bearings in the bearing race.
Rear Hubs and Gearing
- Single speed with coaster brake
- 3-speed (Usually a Sturmey-Archer AW, but sometimes a Sturmey-Archer 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.
- This video provides instructions for adjustment of the AW/AG gears of a Raleigh Twenty. https://www.youtube.com/watch?v=9Bma6jVvUb8
- The majority of Raleigh Twentys came with a Sturmey-Archer AW hub and there has been much discussion about their maintenance and adjustment. Here is a link to the official Adobe (.pdf) format Sturmey-Archer Heritage 1972 Manual, this includes the parts list, dismantling, assembling, maintaining and trouble-shooting with an exploded view of the hub. http://www.sturmey-archerheritage.com/files/view-1046.pdf
Sturmey-Archer Trigger Shifters
- An excellent article on Sturmey-Archer Trigger Shifters for its 3 and 4 speed hubs, 1938 - 1960, was published by Martin Hanczyc in July 2006.
- The article is much too long and detailed for inclusion here but this link will take you to the article: http://genetics.mgh.harvard.edu/hanczyc/pdfs/satriggersjuly06.pdf
- Lots and lots of good information with drawings and pictures, enjoy.
- 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 Raleigh 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.
Rims & Tires (Tyres): There are often questions about rim and tire (tyre) availability for upgrading the Raleigh Twenty so, here's a fairly comprehensive list. Remember that things change and there may be other Rims and Tires (Tyres) available as time passes.
(This section provided by member, davepalk and he uses British English spelling, forgive him.)