Sorry if this is a stupid question. But I occasionally hear a reference to a 28" bicycle wheel. Is this the same as a 700c wheel? (700c wheel diameter is 27.55 inches, maybe someone who doesn't like the metric system is stretching a point?)

Thanks all.........

Maybe: https://www.sheldonbrown.com/tire-sizing.html

Also, 700c tires actually have a 622mm rim diameter.

we have run into this at the shop I work at. Mostly customers looking for 28 inch tubes. we sell them 700c

"28 inches" could be a 700C tire/tube, ISO622mm (an oddball designation for a common size) or a British roadster tire/tube, ISO635mm (a rare but not unknown size in the USA).

...dependent on the mounted and inflated tire's size.

Best,
tcs

It's not odd-ball at all but the only rational tire/rim sizing system in existance. When there are at least three 26" rims/tires, at least three 24" rim/tire and three 20" rim/tire combiantions, as well as 27", 700C, etc.,all different and incompatible, the ISO/ETRTO system is the only way to sort them out.

+1 on the ERTO system... too bad the oddball sizes are often on tires that are too old to read the numbers from!

Some bike manufactures will market their 700c tires and 28" even though as the poster above said, the diameter works out differently than that.

Recently MTB makers are selling 700c rims and tires as 29" to make the confusion even worse.

get this, Schwalbe Supreme tire in 622 diameters is called a 700c when it's 32-40(622)size, but it's a 29x2.00 tire when it's 50-622 size,,which is pretty crazy since it's the same diameter rim. Head over to the Dureme model and the 50-622 tire is called a 28x2.00. So the same size 50-622 size tire gets called a 28" or 29" tire. BUT if you get a 50-622 XR it's called...a 700x50c.

So there you go, one manufacturer with three different designations for tire diameter for the same damn size rim. 700c, 28 or 29!!


https://www.schwalbetires.com/marathon_supreme

https://www.schwalbetires.com/marathon_dureme

Sort of summing up everything in this thread that I can back up with personal experience. 700c (622) is usually the same as 28", and is the same as 29". The interesting thing about this is that 700c is smaller than 27".

A 28" could also be the 650B (584mm rim size), like some of us mountain bikers are using in between the 26 and 29 inch size....

Note to tcs: I misinterpreted your posting in my reply above this one. You were calling the 28" designation odd-ball, not the 622 ISO size designation, Sorry, I didn't mean to insult your interpretation since I agree that there are so many odd-ball names for what is basically the same thing. Thank God for ETRTO/ISO

The classic English roadster 28 x 1 1/2 tire is also marked as 40-635 and 700 x 38B (note it is a 700B tire, not a 700C).

And another thing.... In the French system "700" meant the tire was 700mm across, and "700C" was specifically a tire about 38mm wide. When they mark a tire as 700x25c today, it's neither "700" diameter nor "C" width and the marking makes no sense.

700C refers to a nominal 700 mm diameter at the tread with a 622 mm bead diameter. B is the same thing except 635 bead diameter. The letter specifies the bead diameter.

A 28" tire is not the same size as 700c. 28" is slightly larger than 700c maybe less than half an inch in diameter. Since this amount is insignificant in size of tire; people may install 700c tires on 28" rim and vice versa. I would not do it. On European websites you find tires for 28" categories and 700c categories. Usually 28" tires are made for old classic bikes and some city bikes.

What brings you here, Taimour?

Yet both are bigger then 27.5", go figure.

I miss 2009 too guys, but maybe start a new thread instead of nitpicking something we already know in this one.
Edit to clarify for the poster below me, plural was intended, there are multiple responses between 2009 and this post.

"Guy," singular, not "guys."

In the old French system, 700 referred to the outside diameter in mm and a/b/c/d referred to the tire width.

The 40mm c-width mapped a 700mm outside diameter with a 622mm bead diameter.

Eventually 700c came to dominate and all 622 bead diameters came to be referred to as 700c independent of width. The road tires are generally narrower so it results in a smaller diameter for 700c than 27 inch, even though 700mm is larger than 27 inches. The 28 name came to be applied to 700c to distinguish from 27 inch road tires particularly since the 28 inch 635mm bead diameter roadster tires (well suited for cobblestone) were disappearing and 26 would have confused with the common 26 inch road tires (generally in the 584-600mm bead diameters-brand specific). This in spite of the 700c road tires actually being smaller than 27 inch tires.



29ers- at 622x50 give a 29 inch outside diameter so 29 is actually reflective of their outside diameter.



I’ve generally been hearing the 650b mountain bike tires referred to as 27.5 (In the old French system b was a fairly moderately narrow general tire but wide road tire at 32mm wide tire-using the bead from the old narrow 650b on a wide tire gives a larger diameter) as a compromise between 26 and 29 rather than reflective of their diameter. The 650b road tire size is still common in France only.

Little-Acorn asked the not-stupid question in 2009. He has not been active on BF since 2010.
This Zombie Thread had been dormant for 11 years until it was awakened yesterday.

I was corrected and "clarified" just the other day on a 10 year old thread. These threads that still come up in searches can be updated, corrected, clarified with technical information. Whether a thread is worthy of keeping alive or resurrected IMO is dependent on the quality and density of the information.

Well, I need the answer and it’s January 2021. Can’t set up my computer because my tire says 28” but the wheel says 700c

Well the first suggestion in this over 10 y.o. thread should give you enough information to know for yourself.

What exactly are you not understanding and what exact tire do you have. Somewhere on that tire is likely to be the ISO size of that tire. Probably in the tiniest print embossed in the sidewall material.