Originally Posted by
the sci guy
I used the googles and couldn't find a chart...
I'm wondering what the basic equivalency is for a 27 x 1.25 tire is in 700c width? Like 700x32 or 35?
I've got the 27" wheels on one bike and 700c on another and the 700c one is in the market for new tires and I want to go wider. I did a test fit of the 27" on the other bike (since it originally had 27" wheels) and that width fit the frame, so I'm looking to go about that width or just slightly less in a 700c.
Thanks.
There is no such thing as 27 x 1.25. It's 27 x 1 1/4. As you'll see on Sheldon's
site, two tires with what should be identical widths, one expressed as a decimal and one as a fraction, will never be the same. What you need to pay attention to is the ERTRO designation, which is the bead seat diameter. 27" is 650, 700C is 622. Regardless of the width, those two tires will never fit on the same rim. It gets even hairier when you get to 26". There are quite a few 26" sizes: MTB 26" is ERTRO 559; 650B aka 26 x 1 1/2" is 584; 26 x 1 3/8" English 3-speed size is 590 and there are several other more obscure sizes called 26".
You may be able to convert your 27" bicycle to use 700C wheels by using longer reach brakes. At that point, the actual width of the tire -- what will actually fit -- should be your guide. In some cases, that may actually be wider than the original.