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My bike's manufacturer page specifies that it has a rim size of 700CX14GX36H. It provides a tire size of 7X28C. It also mentions that it uses high performance 700C tires, which I think is also referenced in the rim size.

I just replaced my tube by myself for the first time, and it was easy enough to determine that I needed a 700x28c size tube, but I would really like to know what all these specifications I'm seeing mean.

Can someone provide an explanation of what general rim, tire and tube size specifications mean?

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700CX14GX36H means it's a:

  • 700c rim (actually ISO 622mm diameter, as the Sheldon Brown page linked by Brad describes)
  • taking 14 gauge spokes
  • with 36 spoke holes

So, you need to know the 700c bit if you're buying tyres or tubes, you need to know the 14g bit if you're replacing spokes, and you need to know the 36H bit if you're re-lacing the rim to a new hub (which will need to have 36 spoke holes to match).

Some Context

700c and 14 gauge spokes is standard for road bike wheels. 36 is a fairly high spoke count, meaning it should be durable and relatively easy to repair and re-true. On the other hand, lower spoke-count wheels may be lighter and more aerodynamic (at the possible cost of being more fragile and harder to repair).


Can someone provide an explanation of what general tire and tube size specifications mean?

700x23 means a tyre fitting a 700c rim, with approximate inflated cross-sectional diameter of 23mm. 700x32 is a fatter (32mm vs. 23mm) tyre for the same diameter rim. Note that even for the "correct" diameter, different tyres fit more or less easily on different rims.

A tube described as 700x18-23 would fit the first (700x23) tyre, but would be likely to burst before filling the greater volume of the fatter 700x32 tyre.

As for a general explanation ... Sheldon's table is probably the best you're going to get.

  • 2
    It should be noted that that nomenclature is just the rim nomenclature, and it oddly doesn't (per the above description) define the rim width. A tire will come with an entirely different string of incomprehensible numbers. – Daniel R Hicks Aug 3 '12 at 20:21

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