I'm pretty enthusiastic about wheels, and, at the risk of being banned for un-Douglas-like activities, I'd like to share with you the tyre I fitted yesterday and the wheel I built to fit it on.
The tyre is an Australian-made Dunlop Thornproof, wired on, 28 x 1 3/4", age unknown but certainly pre-1960. To clean it up I wiped it over with a rag dampened in a glycerine-water mix. Glycerine can be bought from the local pharmacy as a treatment for roughened skin. It seems to work well for softening old rubber, but I am not sure if it is a "correct" treatment. Certainly better than Armor-all that should never enter your shed. I've tried glycerine on a range of old rubber products with good success, but have no idea of what might happen on modern synthetic rubbers.
The rim is hand made in Italy from laminated Ash. Yep, it's wood. I paid extra for a carbon fibre insert to strengthen the rim and allow the tyre to be inflated to higher pressure without fear of damage. The bead seat diameter is 622mm, which means that as well as fitting an old 28 x 1 3/4" tyre (no longer available, but 28 - 2 x (1 3/4) = 24 1/2" = 622mm), it can also use any of the new 700c tyre sizes. There are many to choose from.
The tube is 700c x 47, with a Presta valve. Readily available. A normal (Schraeder) valve requires a relatively large hole, but wood is better than hole for strength. The original valve would have been a Woods - you might remember them from the 1960s but almost unused now.
The original rim had been eaten by white ants, but was for a tubular (glue-on) tyre. New tryes for tubular rims are not readily available in large sizes, although you can get display-only tyres to keep the rims off the floor. I intend to ride the bike.
The spokes are single-butted stainless steel, from the US. 13g for an inch or so at the hub end, then 14g for the rest of their length.
The nipples are extra-long to reach through the wooden rim. They were supplied with the rim, as were the oval spoke washers to go between the nipples and the carbon-fiber mat on the inside of the rim.
I used a 16-mm adhesive cloth rim tape to cover the ends of the nipples, to protect the tube.
The hub is the original.
Since the wheel has 40 spokes, I built it up 4-cross which gives full tangential spoke pattern. Technically even a 36-hole wheel can be built 4-cross, but on a motor cycle the spokes are relatively fat and can foul each other at the hub for some combinations of flange size, spoke size, and pattern. I chose to cross the out-board spokes under the last-crossed spoke in bicycle fashion - i.e. it crosses three spokes on the outside and goes under the fourth. This is sometimes done on early motorcycle wheels, but usually only up to about 12g spoke thickness.
Anyway, I'm very excited by my new wheel. I has been a big job planning it, and a huge amount of fun building it. Oh, by the way, the bike is a 1903 Columbia motorcycle (from the USA), but I might get away with this post if I mention that these rims would look lovely on a Fairy!
Cheers
Leon
