Mine is in original condition and will likely to remain that way.
There are a few things to consider if you want to upgrade - Raleigh used a unique to them threading on the bottom bracket and headset. The bottom bracket axle is also longer than normal. Replacement can be tricky to find but you can replace the lower race of the headset with any other 1" threaded headset and it will work. The top had a bushing rather than a bearing which is unusual but if it is worn, it's possible to shim it. Any standard quill stem will fit.
There is someone on
ebay selling cotterless conversions for Raleighs but I've never tried to use one of these kits. I would definitely question the axle length before buying.
Alloy wheels in the 20 x 1 3/8" (451) size are out there but are tricky to come by at sensible prices. Check the number of spokes if re-using the original hubs. R20s had 28 back and front.
Weinmann centre pulls would improve braking performance big time and should be cheap enough to buy. You will require cable hangers.
If changing the front hub, Raleigh used a narrower axle which was 5/16" in diameter. You will need to spread the forks and file the drop outs (carefully) to use just about any other hub.
I love my R20 but if I really wanted a old small wheeler to customise, I would go with a Puch Pic-Nic. Slightly lighter, rides just as well and built with standard headset and bottom bracket parts and the 406 BMX sized wheels which have a huge range of rims and tyres available. A Dawes Kingpin is vastly superior to either but more difficult to find and I think some had odd wheel sizes as well.
