What 700c means
“700c” is a French-origin size name. The 700 refers to an approximate outside diameter in millimeters, and the c was part of an old lettering scheme for rim diameters. Neither number is a precise measure today. What matters is that a 700c wheel has a bead seat diameter of 622 mm, and nearly every modern road, hybrid and gravel bike with this label uses that rim size.
Actual dimensions
The rim bead seat is 622 mm. The outside diameter of a mounted tire is roughly 27 to 28 inches, depending on tire width. So the label says 700 mm, but the real tire is a bit bigger on a wider tire. It is the rim diameter that determines compatibility.
Is 700c the same as 29 inch, 28 inch, 27 inch or 26 inch?
- 29 inch: Yes for rim size. A 29er mountain bike wheel uses the same 622 mm bead seat as 700c. Tires are usually much wider, and frame clearance determines what fits.
- 28 inch: On most modern bikes, yes, 622 mm. Some older 28 inch sizes, such as 28 x 1 1/2, use 635 mm and are not the same.
- 27 inch: No. Older 27 inch wheels (27 x 1 1/4) use a 630 mm bead seat, so tires and rims are not interchangeable with 700c.
- 26 inch: No. A 26 inch mountain wheel is 559 mm, much smaller than 622 mm. See converting between sizes.
Typical tire widths by bike type
- Road bikes: commonly roughly 25 to 32 mm
- Hybrid and commuter: roughly 30 to 40 mm
- Gravel and cyclocross: roughly 30 to 50 mm, sometimes more
- 29er mountain bikes: roughly 2.1 to 2.6 inches
Real limits come from your frame, fork, brakes and rim width, so check manufacturer specs.
Fitting a tire: rim and frame
For a new tire:
- Confirm the rim bead seat is 622 mm, shown as 622 in the ETRTO marking.
- Pick a width inside the range recommended for your rim.
- Check clearance at the fork crown, chainstays and brake bridge, with a few millimeters to spare for mud and flex.
For measurement tips, see how to find and measure your bike tire size.
Choosing between 700c and 650b
A smaller 650b wheel lets some frames take a wider tire with a similar overall diameter. 700c tends to be the default for road and many gravel bikes. See 650b tires for the comparison. For the system behind all of these names, read bike tire sizes explained.