Mine came with 1.75 x 406 tires. They barely fit between the stock front forks, had a bit more clearance in the rear. I'm running 1.5 x 406 Schwalbe Marathons now. 1.95 seems like a bit of a stretch on a R20, but might work OK on narrower alloy BMX rims.
Two pictures of my nonfolding Twenty. The tires are Kenda 1.95 x 20s. First is of the rear clearance and second is of the front clearance. The clearance is slightly bigger than it appears as the camera makes it look smaller. Roger
I'm thinking about adding a Twenty to my herd of old British bikes.
The decider would be whether I can run my favorite tires.
Will they take 60mm Big Apples? 50mm? With fenders?
If they'll fit in the back, I could build a wider fork.
Here is a picture of one of my '20s with Maxis Hookworm 406x1.95" (50mm) tires and some improvised fenders. I don't think they would go one the stock rims and the stock fork is made for a very narrow front hub. This bike has a recumbent fork with standard dropout spacing.
I actually don't think that a 60mm tire will fit in the rear but I could be wrong.
If you have a calipers, could you get an actual width on the Kenda 1.95" for me? I may have a chance to buy one with a fork like yours. If I could run the 50mm Big Apple I'd buy it and sell the one I just bought. It won't fit in the Raleigh style fork.
According to my digital caliper the tires measure 46.90 mm (1.86") wide on 2.54 mm wide rims. There is about 4+ mm clearance on both side between the tire and the fork. Do you know a way of dating a Twenty? Roger
That thing is supposed to be on the front of the fork behind the brake with the tab pointed up. It hits the flange on the back of the head tube to keep the fork from rotating beyond 90 degrees. Not sure why it's necessary but it's standard equipment. Maybe to keep the cables from getting twisted around.
A 50mm Big Apple would fit. But the guy got back to me and said he'd been wrong about the fork and it's the Raleigh type after all. Dang!
I just checked a 50 x 559 and a 50 x 305 and there is a lot more difference, 4mm, than can be accounted for by the difference in rim width. The 305, on an Alex X-101 rim would give me about 1mm clearance with the fork I have. (I build my wheels to +/- 0.004" and they stay true. so this should be enough) I just need to find out if the 50 x 406 cross section is like the 305 or the 559. All my 406s are 60mm.
I suspect I am SOL as the only markings on the frame are the head badge and a Raleigh sticker of some sorts near the bottom bracket. There is a fade mark of what was a long oval shaped decal on the main tube between the seat tube and the head tube. for what it worth this one is not a folder but I will try to include pictures of the two folders I have also. I will try to get some pictures tomorrow. Roger
Here are the pictures of my three bikes. First is a non folder headbadge that I would like to know the year of. The second is of the remaining decal on the non folder. The third is of the non folding bike. Fourth is of my brown folder that says Raleigh on it and has a hub date of Jan. 1976. The last is of my Green folder that says Twenty on it. Roger
Hmm it's hard to tell without the decal on the brown one but i'd say - what with the non curved stem (early models 68-70something have a more elegant swanlike stem) and alu rack it is a mid period one from the mid-late seventies. Your green one is a bit earlier but still no swanneck stem so I'd guess around 73-75. This is all 'reaching' and based on hunches rather than facts you understand.