wheel size

Dennis Vaughn asked:

Quoted message said:

What are the main differences between the 700 mm tire/wheelset and the 27 inch wheel? Besides
size, how much larger/smaller is the 700 wheel than the 27 inch wheel, and is this overall
diameter measurement or just wheel rim measurement?

"27 inch" wheels are 8 mm larger in diameter than "700c" wheels. This is not enough to make any
important functional difference, but is enough to make the tires incompatible.

For details and explanation, see: sheldonbrown.comtire sizing.htmlOpen ↗

Sheldon "Still Uses 27s" Brown +---------------------------------------------+
| The nice thing about standards is that | there are so many of them to choose from. | --Andrew S.
| Tanenbaum |
+---------------------------------------------+ Harris Cyclery, West Newton, Massachusetts Phone
617-244-9772 FAX 617-244-1041 harriscyclery.comharriscyclery.comOpen ↗ Hard-to-find parts shipped Worldwide
captainbike.comcaptainbike.comOpen ↗ sheldonbrown.comsheldonbrown.comOpen ↗

I guess my question is this: What is the diameter of 700c wheel with the tire inflated to full
pressure 700mm? I realize this may seem trival, but I am looking to upgrade wheels and wonder if the
wheelset will fit. If the 27" wheel is larger I'm sure the bike will fit 27" wheels. "Sheldon Brown"
<[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Dennis Vaughn asked:

Quoted message said:

What are the main differences between the 700 mm tire/wheelset and the

27

Quoted message said:

Quoted message said:

inch wheel? Besides size, how much larger/smaller is the 700 wheel than

the

Quoted message said:

Quoted message said:

27 inch wheel, and is this overall diameter measurement or just wheel

rim

Quoted message said:

Quoted message said:

measurement?

"27 inch" wheels are 8 mm larger in diameter than "700c" wheels. This is not enough to make any
important functional difference, but is enough to make the tires incompatible.

For details and explanation, see: sheldonbrown.comtire sizing.htmlOpen ↗

Sheldon "Still Uses 27s" Brown +---------------------------------------------+
| The nice thing about standards is that | there are so many of them to choose from. | --Andrew
| S. Tanenbaum |
+---------------------------------------------+ Harris Cyclery, West Newton, Massachusetts Phone
617-244-9772 FAX 617-244-1041 harriscyclery.comharriscyclery.comOpen ↗ Hard-to-find parts shipped Worldwide
captainbike.comcaptainbike.comOpen ↗ sheldonbrown.comsheldonbrown.comOpen ↗

Dennis Vaughn said:

I guess my question is this: What is the diameter of 700c wheel with the tire inflated to full
pressure 700mm? I realize this may seem trival, but I am looking to upgrade wheels and wonder if
the wheelset will fit. If the 27" wheel is larger I'm sure the bike will fit 27" wheels.

It depends a lot on the tire you fit. '27"' wheels are 630 mm bead, 700C is 622. Then, the tires
will generally aproximately add on the same as their thickness to that (twice -- one on either
side). 622-35 will be a lot bigger than 630-18.

Jasper

Sheldon Brown <[email hidden]> brightened my day with his incisive wit when in
"]news:[email hidden] he conjectured that:

Quoted message said:

sheldonbrown.comtire sizing.htmlOpen ↗

re: your section about traditional tyre sizing : why don't they refer to diameter as internal
diameter? e.g hub or axis out to the tyre beading? I am assuming of course that the size
disrcepancies you refer to are simply the different "height" for want of a better word, of the tyres
in question.

--
Walter Mitty.

Sheldon Brown said:

+---------------------------------------------+
| The nice thing about standards is that | there are so many of them to choose from. | --Andrew S.
| Tanenbaum |
+---------------------------------------------+

"The important thing about standards is not that everyone agrees with them, but that everyone abides
by them."
-- Tom Hastings
--Digital Equipment Corporation (RIP)
--1968 (or so)

jeverett3<AT>earthlink<DOT>net home.earthlink.net~jeverett3Open ↗

Dennis Vaughn said:

I guess my question is this: What is the diameter of 700c wheel with the tire inflated to full
pressure 700mm?

The diameter is approximately 622 mm plus twice the tire width. So a 700x25C is 672 mm in diameter.

As you can see from Sheldon's article, wheels used to be measured to the outside of the tire tread.
A 700C wheel is 700 mm in diameter with a size "C" tire fitted to it (or a 39 mm tire). 700A and
700B were wheels of the same outer diameter, but with thinner tires and larger rims. Modern wheels
have standard rim sizes and various tires that fit, so the old sizing nomenclature is archaic.

I get a kick out of seeing a tire referred to as, say, "38C", without the 700. Most egregious
example I've seen is in the first question on the rather goofy League of American Bicyclists BikeEd
instructor's pretest. It was just an indicator of the level of questions to follow. I'll dig it up
sometime and post here for laughs.

Quoted message said:

I realize this may seem trival, but I am looking to upgrade wheels and wonder if the wheelset will
fit. If the 27" wheel is larger I'm sure the bike will fit 27" wheels.

700C and 27-inch wheels are generally interchangeable, it is only 4 mm in radius, which is the
relevant dimension (not diameter). I've switched among sizes often in a pinch.

However, if you have 27-inch wheels and your brake pads are at the very bottom of their slots, you
may have problems with 700C wheels. If you have 700C wheels and the pads are at the very top of
their slots or if your preferred tire size barely fits the frame, you may have problems with
27-inch wheels.

Eric Salathe