Wheel Diameter Clarification
09-04-20, 03:42 PM
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I don’t agree on the 650 size. It would depend on which “650” is being used. A 650C has a bead diameter of 571mm while a 650B has a bead diameter of 584mm. Just asking for a “650” tire should raise the question of which one.
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09-04-20, 04:04 PM
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700C and 29" should be interchangeable, but a the width should be proportional. While they have the same actual rim diameter, you would not want a 23mm wide 700C road tire on a 29er rim with a 35mm width. That's just silly.
Same goes for 650B rims and those labeled 27.5".
I have a road bike in my home with 650C wheels, which is yet another rim diameter.
Same goes for 650B rims and those labeled 27.5".
I have a road bike in my home with 650C wheels, which is yet another rim diameter.
09-04-20, 05:27 PM
#6
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That's why the ETRTO numbers matter, Clarity.. bead seat diameter.. 584 mm is 650B & 27.1/2 622 mm is 700C & 29er..
the other data : rim and tire width .. Measure!
the other data : rim and tire width .. Measure!
09-04-20, 05:55 PM
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As @cyccommute mentioned above, it depends on what size you mean. 650A is a 590mm bead seat diameter, 650B is a 584mm bead seat diameter, and 650C is a 571mm bead seat diameter. 700C is a 622mm bead seat diameter, as is the "27.5" size, but a 27" tire has a 630mm bead seat diameter.
It's a mess, and thankfully all these archaic ABC and inch size designations have been deprecated in favor of the ETRTO/ISO tire size designations. ETRTO tire sizes consist of two numbers separated by a hyphen. The first number of the pair is the nominal width of the tire, and the second is the bead seat diameter. Bicycle rims can generally accept a wide range of widths, so it isn't terribly important as long as it is reasonably close to whatever tire you're replacing. The second number is important, because if the bead seat diameter isn't right, you won't be able to mount the tire.
In ETRTO terms, a 650A tire would be marked nn-590 (where "nn" is the nominal width in millimeters, e.g. 38-590); a 650B tire would be nn-584, a 650C tire would be nn-571, a 700C or a "27.5" tire would be nn-622, and a 27" tire would be nn-630.
It's a mess, and thankfully all these archaic ABC and inch size designations have been deprecated in favor of the ETRTO/ISO tire size designations. ETRTO tire sizes consist of two numbers separated by a hyphen. The first number of the pair is the nominal width of the tire, and the second is the bead seat diameter. Bicycle rims can generally accept a wide range of widths, so it isn't terribly important as long as it is reasonably close to whatever tire you're replacing. The second number is important, because if the bead seat diameter isn't right, you won't be able to mount the tire.
In ETRTO terms, a 650A tire would be marked nn-590 (where "nn" is the nominal width in millimeters, e.g. 38-590); a 650B tire would be nn-584, a 650C tire would be nn-571, a 700C or a "27.5" tire would be nn-622, and a 27" tire would be nn-630.
09-04-20, 06:13 PM
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As @cyccommute mentioned above, it depends on what size you mean. 650A is a 590mm bead seat diameter, 650B is a 584mm bead seat diameter, and 650C is a 571mm bead seat diameter. 700C is a 622mm bead seat diameter, as is the "27.5" size, but a 27" tire has a 630mm bead seat diameter.
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09-04-20, 06:14 PM
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I googled but didn't find a pronounciation for "ETRTO", or do people just say "edie-ardeeyo".
09-04-20, 06:21 PM
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As @cyccommute mentioned above, it depends on what size you mean. 650A is a 590mm bead seat diameter, 650B is a 584mm bead seat diameter, and 650C is a 571mm bead seat diameter. 700C is a 622mm bead seat diameter, as is the "27.5" size, but a 27" tire has a 630mm bead seat diameter.
It's a mess, and thankfully all these archaic ABC and inch size designations have been deprecated in favor of the ETRTO/ISO tire size designations. ETRTO tire sizes consist of two numbers separated by a hyphen. The first number of the pair is the nominal width of the tire, and the second is the bead seat diameter. Bicycle rims can generally accept a wide range of widths, so it isn't terribly important as long as it is reasonably close to whatever tire you're replacing. The second number is important, because if the bead seat diameter isn't right, you won't be able to mount the tire.
In ETRTO terms, a 650A tire would be marked nn-590 (where "nn" is the nominal width in millimeters, e.g. 38-590); a 650B tire would be nn-584, a 650C tire would be nn-571, a 700C or a "27.5" tire would be nn-622, and a 27" tire would be nn-630.
It's a mess, and thankfully all these archaic ABC and inch size designations have been deprecated in favor of the ETRTO/ISO tire size designations. ETRTO tire sizes consist of two numbers separated by a hyphen. The first number of the pair is the nominal width of the tire, and the second is the bead seat diameter. Bicycle rims can generally accept a wide range of widths, so it isn't terribly important as long as it is reasonably close to whatever tire you're replacing. The second number is important, because if the bead seat diameter isn't right, you won't be able to mount the tire.
In ETRTO terms, a 650A tire would be marked nn-590 (where "nn" is the nominal width in millimeters, e.g. 38-590); a 650B tire would be nn-584, a 650C tire would be nn-571, a 700C or a "27.5" tire would be nn-622, and a 27" tire would be nn-630.
Otto
09-04-20, 07:31 PM
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Yup, And a 27" tubular fits a tubular rim interchangeable (caliper brake-wise) with 700c/622mm bead rims (I don't believe tubulars were even make in English speaking countries, so how 27" appeared on the labeling is beyond me. (Well the English have been riding them long enough - and paying for them - that maybe the European manufacturers pitied them and attached labels they could read.)
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All the above said in humor.
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09-05-20, 05:29 AM
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Yes, you're right. My bad.
The best course of action is to ignore all the archaic ABC and inch size designations and instead rely on the ETRTO/ISO size designations.
09-05-20, 07:30 AM
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27" tires are 630mm everywhere
This is a British bicycle with 28" tires/wheels:
See https://www.sheldonbrown.com/tire-sizing.html for more details.
Last edited by I-Like-To-Bike; 09-05-20 at 07:42 AM.
