Pete said:Hello
I have inherited and old Harry Hall road bike and wish to get it back on the road again. It needs
new tyres for a start but I am not sure which size to get. The old ones have 27x1 and 27x1-1/8
marked on but I can't find reference to these sizes anywhere. The rims measure about 28 mm wide
externally.
27x1-1/4 are still obtainable and will fit. Although it's a general rule that tyres sized in
fractions of inches are not interchangeable (eg: 26x1-3/8 tyres won't fit 26x1-1/4 rims), the
post-war 27 inch series is the one exception [2].
Quoted message said:Can anyone advise me how to measure up for some new tyres.
Go by the ETRTO size - this is 25-630 for the 27x1 and 32-630 for the 27x1-1/8. The 630 bit is the
bead seat diameter in millimetres.
Quoted message said:I have seen lots of 700c x20 x23 x25 and x28.
700C tyres are slightly smaller - 622mm - so will not fit your rim. [1] Changing the bike to 700C
rims is usually within the range of the brakes and will give you a much greater choice of tyres.
But, of course, you sacrifice originality.
Quoted message said:What dot these nembers mean???
You don't want to know... that way madness lies. However, if you choose not to heed this warning,
there's an explanation at users.globalnet.co.ukarc0307.htmOpen ↗
Quoted message said:
Any help would be appreciated.
Pete
[1] though they will fit the pre-war 27x1-1/4 rim size!
[2] OK, I lied, there's another: the Moulton-Wobler^WWolber 17" sizes.
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Andrew Pattle