wheel size

Discussion in 'Cycling Equipment' started by Dennis Vaughn, Jun 17, 2003.

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  1. 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? Thanks, Dennis
     
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  2. Dennis Vaughn asked:
    > 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: http://sheldonbrown.com/tire-sizing.html

    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 http://harriscyclery.com Hard-to-find parts shipped Worldwide
    http://captainbike.com http://sheldonbrown.com
     
  3. 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 protected]> wrote in message news:[email protected]...
    > Dennis Vaughn asked:
    > > 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: http://sheldonbrown.com/tire-sizing.html
    >
    > 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 http://harriscyclery.com Hard-to-find parts shipped Worldwide
    > http://captainbike.com http://sheldonbrown.com
     
  4. On Wed, 18 Jun 2003 02:00:40 -0400, "Dennis Vaughn" <[email protected]> wrote:

    > 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
     
  5. Walter Mitty

    Walter Mitty Guest

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

    > http://sheldonbrown.com/tire-sizing.html

    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.
     
  6. John Everett

    John Everett Guest

    On Wed, 18 Jun 2003 04:11:22 GMT, Sheldon Brown <[email protected]> wrote:

    >+---------------------------------------------+
    >| 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 http://home.earthlink.net/~jeverett3
     
  7. Eric Salathe

    Eric Salathe Guest

    "Dennis Vaughn" wrote:
    > 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.

    > 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
     
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