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29er and 28" tire size

Old 05-16-17, 01:12 PM
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Fluteman
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29er and 28" tire size

Ok..I'm confused now and a question for the experts. I have a set of Cruz Urban Barriers 29x2.0...however, in raised numbers it has CRLX 28x2.0...may I ask for someone to explain this..thank you
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Old 05-16-17, 01:16 PM
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Why do you say you have 29's
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Old 05-16-17, 01:25 PM
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28" and 29" tires both use 700c rims.

The wider the tire profile, the larger the outside diameter of the tire.
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Old 05-16-17, 01:29 PM
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Lots of confusion with tire size names. 29" tire usually means a tire bigger than 2" on a 700c rim, 28" sometimes refers to tires around 2" on a 700c rim. Both those terms are vague, the more precise spec is ERTRO or ISO size, or bead set diameter (BSD). A "29er" tire, as well as a "28 inch" tire, and a "700c" tire, all have a BSD of 622mm.

https://www.sheldonbrown.com/tire-sizing.html
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Old 05-16-17, 01:36 PM
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I'd love it if marketing folks got out of the way and let engineers sell tires based on the rather objective ETRTO standard. No reason at all we need three marketing terms for the same BSD, based on application and geographical region.

Likewise, we don't need at least three different 26" tires out there, that are in no way compatible with one another.
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Old 05-16-17, 01:40 PM
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Tire diameter designation is a load of crap, basically. Most designations refer roughly to inflated width, but this changes between different tires that can all mate to the same rim, and so over the years you get all kinds of different descriptions for the same bead seat diameter.

29", 28", and 700c all refer to a bead seat diameter of 622mm.
27.5" and 650b refer to a bead seat diameter of 584mm.
26er usually refers to a bead seat diameter of 559mm, although there are lots of things called 26 inch.
27" refers to a bead seat diameter of 630mm.

So.

27" > 29" > 27.5"

all perfectly intuitive
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Old 05-16-17, 05:15 PM
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Originally Posted by HTupolev View Post
Tire diameter designation is a load of crap, basically. Most designations refer roughly to inflated width, but this changes between different tires that can all mate to the same rim, and so over the years you get all kinds of different descriptions for the same bead seat diameter.

29", 28", and 700c all refer to a bead seat diameter of 622mm.
27.5" and 650b refer to a bead seat diameter of 584mm.
26er usually refers to a bead seat diameter of 559mm, although there are lots of things called 26 inch.
27" refers to a bead seat diameter of 630mm.

So.

27" > 29" > 27.5"

all perfectly intuitive
Incomplete. Traditionally, 28" referred to British-style bikes with 635mm rims, and sometimes for "common" size tubulars.
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Old 05-16-17, 05:56 PM
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Originally Posted by jefnvk View Post
I'd love it if marketing folks got out of the way and let engineers sell tires based on the rather objective ETRTO standard. No reason at all we need three marketing terms for the same BSD, based on application and geographical region.

Likewise, we don't need at least three different 26" tires out there, that are in no way compatible with one another.
For bike tires, the listed size is basically the outside diameter of the tire, and makes some sense. But, unfortunately rims and bikes were made in several countries around the world, all with slightly different sizes and interpretations.

It is nice that most new modern adult bikes are made with about 4 different rim diameters (which are still quite a few) 26" (MTB), 650b, 650c, & 700c. But, we still have support for over a century of vintage bikes, or some other unique sizes or designs.

Perhaps there is no real need to use essentially the same 700c rims for 23mm road tires, and 50mm MTB tires. But, the advantage comes in being able to fit the intermediate sizes (32mm to 40mm) which are being used on a variety of bikes.

One issue, of course, is mixing types of tires & wheels, for example, trying to match Moped tires to Bicycle wheels. Some combinations work, some combinations don't.
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Old 05-16-17, 05:57 PM
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Originally Posted by AlexCyclistRoch View Post
and sometimes for "common" size tubulars.
Speaking of which, is there an actual name or technical description for that spec? How are tubular rims specified, anyway? Sometimes people call it "700c" because it sticks the brake track in basically the same spot, but that's a dodgy technical description...
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Old 05-16-17, 07:57 PM
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Very interesting and confusing for sure..thanks guys for trying to explain this out.
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Old 05-16-17, 07:58 PM
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Originally Posted by Fastfingaz View Post
Why do you say you have 29's
The size of the tire is 29x2.0
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Old 05-17-17, 03:21 PM
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Originally Posted by HTupolev View Post
Speaking of which, is there an actual name or technical description for that spec? How are tubular rims specified, anyway? Sometimes people call it "700c" because it sticks the brake track in basically the same spot, but that's a dodgy technical description...
Most common tubulars are also 622mmŲ (some racing rims might be a mm or 2 larger, to keep tires mounted under extreme conditions), but you can't call it "700c" because that refers ONLY to clincher tires of the same diameter. It is also NOT 700b, or the exceedingly uncommon 700a.
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Old 05-17-17, 03:47 PM
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Recommended reading:
https://www.sheldonbrown.com/tire-sizing.html
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Old 05-17-17, 04:10 PM
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Originally Posted by tyrion View Post
Lots of confusion with tire size names. 29" tire usually means a tire bigger than 2" on a 700c rim, 28" sometimes refers to tires around 2" on a 700c rim.
28" is the inch-designation that Europeans use for 700C road tires. I agree it's vague and confusing to use these contrived size names. Maybe it's to make you think it's a new and improved size so you'll buy it?
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Old 05-17-17, 04:31 PM
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Originally Posted by CliffordK View Post
For bike tires, the listed size is basically the outside diameter of the tire, and makes some sense. But, unfortunately rims and bikes were made in several countries around the world, all with slightly different sizes and interpretations.
I get where the designation comes from, but at least in my mind, tire rim compatibility is far more important than the approximate outside diameter.

I'm glad I was born after ISO was invented. Not perfect, or universally followed, but making a good effort. Now if we could just get America off the dang imperial/colony hybrid system....
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Old 05-17-17, 05:17 PM
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I agree, I'd prefer to see tires listed as:

700x25, 32, 40, 50, etc. Rather than seeing 28" or 29", or etc. Anybody can also learn widths in inches or mm.

I believe that 26" will stick with the old MTBs, and the 29" was created as a distinction from 26" (using the same format).

I'm not really sure why anybody thought to start using 28". It makes sense that it is smaller than 29", but it just makes a confusing intermediate term.

Of course, MTB riders would have quickly learned if the "new" tires were called 700c or ISO 622.

One advantage, however, is that if I'm looking at a fork, then if it is listed as 29", I'll know it is a BIG fork with lots of clearance (in theory).

One of the issues that will dog the bicycle industry for eons is the mixed terms meaning the same thing. So, twenty years from now, that 28x2 tire will be removed, and the owner will head into a store looking for a match, and will be puzzled if all they can find are 700c x 35mm or 700c x 40mm tires.

Looking for 24" tires, the only way too find the right ones was to look for ISO 520. Any other designation was a mess.
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Old 05-17-17, 07:13 PM
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Originally Posted by CliffordK View Post
I agree, I'd prefer to see tires listed as:

700x25, 32, 40, 50, etc. Rather than seeing 28" or 29", or etc. Anybody can also learn widths in inches or mm.

I believe that 26" will stick with the old MTBs, and the 29" was created as a distinction from 26" (using the same format).

I'm not really sure why anybody thought to start using 28". It makes sense that it is smaller than 29", but it just makes a confusing intermediate term.

Of course, MTB riders would have quickly learned if the "new" tires were called 700c or ISO 622.

One advantage, however, is that if I'm looking at a fork, then if it is listed as 29", I'll know it is a BIG fork with lots of clearance (in theory).

One of the issues that will dog the bicycle industry for eons is the mixed terms meaning the same thing. So, twenty years from now, that 28x2 tire will be removed, and the owner will head into a store looking for a match, and will be puzzled if all they can find are 700c x 35mm or 700c x 40mm tires.

Looking for 24" tires, the only way too find the right ones was to look for ISO 520. Any other designation was a mess.
If it makes you feel any better, the only USA distributor of bicycle parts that does an acceptable job of listing tire sizes seems to be QBP, out of the major bike companies doing their own supplying, and 4 or 5 pure distributors.
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Old 05-17-17, 07:20 PM
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Originally Posted by wschruba View Post
If it makes you feel any better, the only USA distributor of bicycle parts that does an acceptable job of listing tire sizes seems to be QBP, out of the major bike companies doing their own supplying, and 4 or 5 pure distributors.
I don't think I bought anything from them, but a company needs to take care in creating search terms that are easy for a search engine to pick up and index.

The easier to find and understand a listing, the more stuff that gets sold (and probably also fewer returns).
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