Pre 1950s rides of LFGSS: old bikes, vintage rats, classic lightweights

Do these actually take 700c tubulars?

Were 27” tubs a thing?

As Veloham suggests, there never was such a thing as 27" sprints and tubs and this muddle is just another example of metric/imperial problems. Originally, as we know, the Britsh sizes were 26" and 28" and it seems that the bike trade believed that the British cycling public was incapable of understanding anything that was not measured in imperial. Aside from anything else we were so firmly wedded to the concept of gear sizing in inches the idea that the outside diameter of a tyre should be in anything other than an exact number of inches was completely beyond the pale; this is the reason why 26 x 1 and 3/8" and 26 x 1 and 1/4" need different sized rims. Dunlop and Constrictor presumably managed to grasp the fact that the rest of the bike racing world was never going to buy 26" tubs, so they went over to the continental size (although there certainly were 26" tubs pre- war). I know the 700 size was sometimes referred to as 27", but I guess that was just because they couldn't bring themselves to mention millimetres.

This led to the bizarre situation where people who really should have known better (I'm talking about the riders and journalists) quoting racing gears as if tubs were actually 27", so they would refer to 48 x 16 (a very commonly used TT gear in the 50's) as an 81" gear when, on tubs, it was about 79.5". This difference might seem trivial, but remember you have to rev very fast to do a 59 on an 81" gear, let alone 79.5!

Another point here is that for a medium gear event it was assumed that the 72" gear required would be achieved by 48 x 18, but on tubs this will actually give about 70.6". I found it was quite possible to use 49 x 18 (about 72.1"), but whatever advantage I gained from this stratagem it was nowhere near enough to allow me to win. Bugger!

However I'm convinced that in the highly competitive world of 1950's time trialling, a lot of the contenders were severely undergearing and, in addition, subtracting about 1 1/2" from the gear they thought they were using by underestimating their tyre size.