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Tube rupture

Old 02-26-21, 07:34 AM
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Spidylou
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Tube rupture

Hi anyone..
my 27.5 inch mountain tubes always rupture ar bottom of valve stem, usually within 30 minutes of repairing it. Originally thought there was an issue with rear rim, but it has also happened recently on the front tire too. What do I do?? I can't ride it.
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Old 02-26-21, 08:36 AM
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If it happens soon after you change tire and/or tube then I'd have to think you may be doing something wrong. Possibly pushing the bead of the tire over the bottom of the stem damaging the tube caught between.

If your valve stems don't come straight out of the rim and point toward the center of the hub, then there is something wrong that will cause the tube to wear quickly around the valve stem. If it's at an angle after riding your bike, then you likely don't have anywhere near enough air pressure in the tube and it's "walking" in the tire.

If you have a air chuck that locks onto the valve stem and when removed it pulls on the valve stem, well it's worn out and you need a new air chuck.

If you air up your tires with an air chuck you have to hold on the stem and are pushing the valve stem into the rim and bottoming out on the tire, then you are pinching and possibly damaging the tube between.

Regardless, if you figure it out let us know so we can add something else to check for.
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Old 02-26-21, 09:56 AM
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A common situation that adds to the chance of a tube failure (how I dislike that word) is the uneven stretch of the tube about the valve base. If the tube is stretched too much in a local area that area can tear, or rip.

Situation 1 is when a narrow rim with a deep interior beneath the bead seat shelf. The tire's beads take up room and the tube is being pushed past them to the rim's base/bed. Around the valve this space, between the tire beads, is even less and sometimes the valve base can't seat down all the way in the rim. Thus the tube has two bulges, one on each side of the valve. Tubes with a stem base nut (the valve is nutted in place VS the molded style with it's double thick ring around the valve base) see more of this bulge as the base nut also takes up space and prevents the rubber portion of the tube from resting on the rim base.

Situation 2 is when the tire is ridden with too little air pressure to keep it in place, rotation wise. The tire will tend to creep around the rim as the tire wants to both grip the ground/road and the rim at the same time. As rim is turning with the force of our pedaling the tire can slip on the rim (and some motorcycles and cars, drag racers, have their rear tire beads clamped with bolts to the wheel's bead seat). Since the valve is stuck in it's hole, in the rim, it can't slip and instead becomes cocked as it's base is pulled in one direction (the tire sliding on the rim). The being pulled side of the valve gets stretched thinner and thinner as the tire slips more. The other side of the valve sees the tube bunching up (Ask any shop wrench about how many tubes have quite a few inches doubled up on one side of the valve).

So you see sometimes the problem is equipment based and other times by the rider's choice (or lack of awareness). I do feel that the quality of tube rubber has suffered over the decades too. Some tubes could well handle these situations better then another tube as it's rubber (not that real tree sourced rubber is used these days) could be stretchier or less tear/rip prone. Andy
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Old 02-26-21, 11:51 AM
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Sorry.... Have to ask.
Are you installing Presta tubes in a Schrader rim ?

Barry
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Old 02-26-21, 11:54 AM
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Not sure what you mean by 'rupture' - If it is a large irregular shaped tear then that is always caused by the tube escaping the tire somehow - either by improper mounting or a cut or hole through the tire. If it is just damage or a small hole or cut very close to the base of the valve it is either caused by (a) a poor fit of the valve stem in the hole, like using a presta valve tube in a rim drilled for Schrader, a sharp edge on the valve hole, or rough handling when pumping or removing the pump, or because the pump is too tight on the valve stem - I returned a pump to the store because it was very tight on the valve stem and every tube I pumped with it more than once developed a hole near the valve.
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Old 02-26-21, 02:30 PM
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Tire tear revised

Tire label (58=584l 27.5 x 2.35
​​​​650 x 58B
​Rim is aluminum ERD 563
depth of 19mm
​​​19m.650B bead seat 584

Not rupture..I meant tear. I truly can't believe the response. I must start off by sayyng thank u kindly for informing me . I am installing a Presta tube. The Schraeder simply wouldn't fit.
I'll give dimensions soon on both rim and tube. It sounds like that may be the issue. As for inflation. I use a compressor and truly pump it up to its manufacturers pressures. I may be using wrong size tube?? I'll confirm all measurements soon. Thanks everyone. Truly appreciated

Forgot to mention they r double walled rims. If that makes more sense
tires size is

Last edited by Spidylou; 02-26-21 at 03:50 PM. Reason: Not complete
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Old 02-26-21, 03:28 PM
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If you are going by the fantasy size of the tire then you may well have the wrong tube. You need to look for the ISO or ETRTO size on the tire. Sometimes it's easy to find, other times it's part of the tiniest print embossed on the sidewall. The proper format is nn X nnn where nn is the tire casing width (roughly) and the nnn is the BSD, bead seat diameter of the tire. Same convention is used for rims but it's the internal width of the rim at the bead seat and the BSD. If your tire is a 27 five, then your tire might have something like 65 x 584 on it somewhere. Don't confuse if with the fantasy size which is usually written in big letters on the tire.

Sometimes the tire makers use a bastardized ETRTO convention and will have something like 700 x 25C. You just have to know that a 700c tire is 622 BSD and that the "c" after 25 usually means crochet or hooked rims or tire bead.

Now on to tubes....

You want a tube that just fits the inside of your tire and rim. Too much excess and you might have folds and kinks that you can feel while riding and will cause wear on the tube every revolution of the tire. Too little width on the tube and you'll be blowing it up to fill the voids between it and the tire/rim and that will mean you've stretched the tube thinner making it more prone to puncture and acting like a balloon and suddenly going flat instead of gradually flatting from a puncture.

Many tubes will have a range of size tires they fit. Make sure your tire is within that range. Different makers show that range differently, but many will have something that helps you. You are mostly interested in width because you typically don't want to use tubes intended for one BSD tire in another. It can be done, but not desired except for impossible to find anymore sizes or emergencies when you have to have something.


You mentioned you couldn't fit a schrader in your rim. I would have thought most 584 BSD rims would be schrader as they are typically wider rims and the bigger valve stem diameter isn't an issue for them. But maybe not. I don't speak mountain bike very well. <grin> You sure what you have is a real 27.5 or 27 five tire?
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Old 02-26-21, 03:51 PM
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Tire tear revised

Just reposted with tire and rim configuration into the previous post.
confirmed 27.5 x 35
58=584
650x58B

Rim is ERD 563
rim depth is 19mm
650b bead seat
584
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Old 02-26-21, 04:38 PM
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Dodgy rim tape, or a cheap rim with a crap drilling and it's not been clean up properly. Get a round file and clean up the valve hole and then fit a good quality rim tape or use tubeless rim tape and set it up tubeless..
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Old 02-26-21, 05:27 PM
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Originally Posted by Iride01
If you are going by the fantasy size of the tire then you may well have the wrong tube. You need to look for the ISO or ETRTO size on the tire. Sometimes it's easy to find, other times it's part of the tiniest print embossed on the sidewall. The proper format is nn X nnn where nn is the tire casing width (roughly) and the nnn is the BSD, bead seat diameter of the tire. Same convention is used for rims but it's the internal width of the rim at the bead seat and the BSD. If your tire is a 27 five, then your tire might have something like 65 x 584 on it somewhere. Don't confuse if with the fantasy size which is usually written in big letters on the tire.

Sometimes the tire makers use a bastardized ETRTO convention and will have something like 700 x 25C. You just have to know that a 700c tire is 622 BSD and that the "c" after 25 usually means crochet or hooked rims or tire bead.

Now on to tubes....

You want a tube that just fits the inside of your tire and rim. Too much excess and you might have folds and kinks that you can feel while riding and will cause wear on the tube every revolution of the tire. Too little width on the tube and you'll be blowing it up to fill the voids between it and the tire/rim and that will mean you've stretched the tube thinner making it more prone to puncture and acting like a balloon and suddenly going flat instead of gradually flatting from a puncture.

Many tubes will have a range of size tires they fit. Make sure your tire is within that range. Different makers show that range differently, but many will have something that helps you. You are mostly interested in width because you typically don't want to use tubes intended for one BSD tire in another. It can be done, but not desired except for impossible to find anymore sizes or emergencies when you have to have something.


You mentioned you couldn't fit a schrader in your rim. I would have thought most 584 BSD rims would be schrader as they are typically wider rims and the bigger valve stem diameter isn't an issue for them. But maybe not. I don't speak mountain bike very well. <grin> You sure what you have is a real 27.5 or 27 five tire?
I agree with most or all this. The label is there for marketing reasons. The ISO spec is for fitting ones. I generally prefer using tubes that are on the wider side of the possible fit range so that the tube doesn't stretch much as it fills up the rim and tire's interior space.

I hope the bolded is a tongue in cheek attempt. The "C" the sub group designation within the family of 700 "sized" tires. 700 has a 647mm bead seat diameter, 700A is 642mm, 700B is 635mm, 700C is 622mm (and what most mean when they say "700"), 700D is 583mm. Now the OP has a 650B (which is 584mm). 650 is 597mm (and what Schwinn calls 26x 1 1/4-1 3/8 or EA1), 650A is 590 (what most call 26x1 3/8 and 650C is 571mm.

The reason for these series of rim bead seat diameters was, as I was taught, that one time when most bikes used hub brakes the same outside tire diameter could be had but with increasing tire widths and thus decreasing bead seat diameters. Kind of like what so many currently think is really cool with swapping out 29er tire/rims for wider 27.5s. (or translated as 622 ISO for wider tired 584 ISO.) Andy (who has seen the old claimed as the new way many times, but with a different term so to claim the newness as theirs)
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Old 02-26-21, 05:45 PM
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One thing I always do is once the tire and tube are mounted to the rim, I push the valve stem down into the tire, wiggle the tire bead a bit to make sure it seats properly on the lip of the rim then inflate to around 10 lbs.

I check that the valve stem is down inside the tire and not sandwiched between the tire bead and the rim then slowly inflate to around 20 lbs, spin the wheel checking for proper bead seating then inflate all the way. I do this with Schraeder and Presta. Yeah, it takes an extra 30 seconds but it's worth it to me.
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Old 02-26-21, 06:14 PM
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Originally Posted by Andrew R Stewart
Originally Posted by Iride01
Sometimes the tire makers use a bastardized ETRTO convention and will have something like 700 x 25C. You just have to know that a 700c tire is 622 BSD and that the "c" after 25 usually means crochet or hooked rims or tire bead.
I hope the bolded is a tongue in cheek attempt. The "C" the sub group designation within the family of 700 "sized" tires. 700 has a 647mm bead seat diameter, 700A is 642mm, 700B is 635mm, 700C is 622mm (and what most mean when they say "700"), 700D is 583mm. Now the OP has a 650B (which is 584mm). 650 is 597mm (and what Schwinn calls 26x 1 1/4-1 3/8 or EA1), 650A is 590 (what most call 26x1 3/8 and 650C is 571mm.
Sometimes maybe, but I've seen several times in FAQ's by various mfrs that the "C" is for crochet beads when it comes after the width.

Although it doesn't specifically state it for the tire section of ISO 5775 for the rim section 5775-2 it states:
Rims are designated by their nominal rim diameter and their nominal width, separated by a cross (×). Both are measured in millimeters. The rim type codes SS or HB precede the rim designation, whereas code C is appended to the nominal width

Examples:
SS 400×20, HB 422×25, 620×13C
https://en.wikipedia.org/wiki/ISO_5775#Rims

If you look at the tables in the tire section the use of A, B, C and others don't seem to coincide perfectly with the BSD's of rims I know as typical french sizes. So this furthers my belief that I did see some mfr's state in some of their literature that the C after the width on their tires was for crochet.
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Old 02-26-21, 07:20 PM
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Is the term "crochet" trying to mean the same as "hooked bead" (HB)? If so it's a poor reference till all agree, where as hooked bead is far more descriptive to what's actually the shape that's in play. But like I said in so many words, every generation feels the need to re term the old so to claim it as the new way.

Here's the way I was taught. This is page 12-4 from Sutherlands 6th manual, (published 1995). Note in the French section the "C" (of 700x35C) is listed as the code, not a rim/tire bead design reference. IIRC the vast majority of rim designs when this lettered code was being created were of non hooked edge, steel folded and rolled being the common manufacturing process. When extruded Al rims began coming to market they followed this same tire/rim interface. I believe it was the mid 1970s when hooked edge rims became popular, among the performance riders first due to their looking for less weight of skinnier tires which required more pressure to keep the rim off the road. So as roads improved and riders could get away with narrower and higher pressure tires the rim diameters for equally diametered tires increased to maintain the tire frame fit.

Each manufacturer of rims/tires catered first to their OEM customers and secondarily to the repair/after market. As bike manufacturers began to export their bikes to other countries the issue of what tire fits what bike began to become more a problem and various attempts began to "standardize" both size markings as well as actual production. The ISO's ETRTO numbering system is the current attempt that has pretty much been adapted by most. Andy

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Old 02-26-21, 07:41 PM
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I bought a bunch of tubes on sale and when installed they were a bit "iffy"; two out of four failed within five minutes of the install and all at the base of the stem. Each had a failure that was just like a tear at the bottom of the stem. It looked like a rubber failure in the tube. After four tubes I got them to hold air at 110 psi. Sometimes you get some defective tubes. Smiles, MH
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Old 02-27-21, 11:22 AM
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Originally Posted by Andrew R Stewart
Is the term "crochet" trying to mean the same as "hooked bead" (HB)?
There is a slight difference between hooked bead and crochet, but I think true hooked bead tires or rims that are truly only for hooked beads are few and far between. Hooked bead work well on crochet type rims for the most part. A true hooked bead only has to have the radiused edge for the bead.

The difference is that there will be a small smooth vertical or nearly vertical wall coming down the inside of a rim made for crochet type tires. Which most every rim I've had or seen are crochet. Except for my Schwinn bikes from the 70's with steel rims that were a smooth bead that is now becoming popular again for the tubeless tire/rim makers.

Fact is most everyone lumps crochet and hooked bead tires and rims into being pretty much the same thing. The terminology was established before most people here where born. And the terms are more about what was space age bleeding tech at the time. A standard that doesn't have a lot of enforcement behind it. And probably the fact that it's easy to imagine what a hooked bead is than a crochet bead even though true hooked bead rims are few and far between. I've never really seen one. And many manufacturers will refer to their crochet type rims as hooked bead. Which they are at the very minimum.

I do too.
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Old 03-01-21, 09:12 AM
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What a crochet/hook bead is or isn't is beside the point. The 'C' in XXX x YYC does not now and never has stood for 'crochet' sidewall rims. If it did, what do A,B, and D stand for in the same sizing system?
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Old 03-01-21, 09:31 AM
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Originally Posted by Iride01
Sometimes maybe, but I've seen several times in FAQ's by various mfrs that the "C" is for crochet beads when it comes after the width.

Although it doesn't specifically state it for the tire section of ISO 5775 for the rim section 5775-2 it states:
https://en.wikipedia.org/wiki/ISO_5775#Rims

If you look at the tables in the tire section the use of A, B, C and others don't seem to coincide perfectly with the BSD's of rims I know as typical french sizes. So this furthers my belief that I did see some mfr's state in some of their literature that the C after the width on their tires was for crochet.
The wiki article is wrong. If C stood for Crochet then what do A, B and D stand for in the same systems? Trick question - they don't stand for anything, but are codes for the different sizes that have the same nominal outside diameter.

If I am wrong, please link to the manufacturer FAQs that support your claim. I looked and could not find such claims except for in the erroneous Wiki article, which does not have a source linked.
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Old 03-01-21, 11:28 AM
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Originally Posted by ClydeClydeson
The wiki article is wrong. If C stood for Crochet then what do A, B and D stand for in the same systems? Trick question - they don't stand for anything, but are codes for the different sizes that have the same nominal outside diameter.

If I am wrong, please link to the manufacturer FAQs that support your claim. I looked and could not find such claims except for in the erroneous Wiki article, which does not have a source linked.
Well here you go.....
Continental recommends that you mount bicycle tyres on hook edge type rims only. Hook edge type rims provide a more secure hold, especially with air pressures exceeding 44 PSI (3 bar). These advantages are safety-relevant. From 73 PSI (5 bar) onwards, the hook edge type rims are even stipulated by the ETRTO guideline. This rim type, for example 622 x 13C, is indicated with a rim base diameter in mm (size D), the rim width in mm (size A) and a “C” for crotchet (Illustration 6 ). If the size information on older rims is no longer legible, the rim width can simply be measured by using a calliper from one hook edge to the other. An overview listing the appropriate rim width for every tyre size is also available from ETRTO (also look at the chart 7 ).
https://blobs.continental-tires.com/...otice-data.pdf

To me it makes no sense that the mfr will care to put a C to make some vague reference to an outdated sizing mode. It makes more sense that they would put C after the width to tell you that it is only intended only for a crochet type rim. Some don't care whether you use them on a crochet, hooked bead or smooth rim.

Smooth bead rims have been fairly extinct since the demise of Schwinn and their 27 and 26 inch smooth steel rims. Perhaps since the tubeless crowd is now getting some smooth bead rims we'll see some more on what this truly means.

Maybe they'll clear up the difference between hooked and crochet too. Because while a crochet bead is a type of hooked bead, a hooked bead is not necessarily a crochet bead.

Last edited by Iride01; 03-01-21 at 11:33 AM.
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Old 03-01-21, 11:42 AM
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Originally Posted by Iride01
Well here you go.....
https://blobs.continental-tires.com/...otice-data.pdf

To me it makes no sense that the mfr will care to put a C to make some vague reference to an outdated sizing mode. It makes more sense that they would put C after the width to tell you that it is only intended only for a crochet type rim.
You're right - it doesn't make logical sense - like humans being born with a pinky toe or an appendix. But it is what it is. Yours (and Conti's) explanation also doesn't make sense - it falls apart on any other French size - if C stands of Crochet, what do A, B, and D stand for? 27.5" tires are also commonly called 650B (Tires generally labelled as 650x40B), and 3-speed 26x1-3/8 tires are called 650x35A. These letter codes pre-date crochet bead rims. Saying the C stands for 'Crochet' is likely apocryphal.
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Old 03-01-21, 12:09 PM
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Originally Posted by ClydeClydeson
You're right - it doesn't make logical sense - like humans being born with a pinky toe or an appendix. But it is what it is. Yours (and Conti's) explanation also doesn't make sense - it falls apart on any other French size - if C stands of Crochet, what do A, B, and D stand for? 27.5" tires are also commonly called 650B (Tires generally labelled as 650x40B), and 3-speed 26x1-3/8 tires are called 650x35A. These letter codes pre-date crochet bead rims. Saying the C stands for 'Crochet' is likely apocryphal.
We are simply talking about what the "C" means when on a tire that sometimes might be shown as 622 x 25C by one manufacturer or 700x25C by another. Some only put 622x25 or 700x25.

I don't know how Continental's explanation falls apart for you. They say it means they want their tire on a crochet type rim.

I've never seen a tire with A, B, or D after the width when expressed as above. I have seen 650B and 650C and 700C, but those are true french tire sizing where no info as to the BSD of the tire is given. And that was the crux of the problem with the french sizing that probably brought about the ETRTO standard that later gave way to ISO.
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Old 03-01-21, 12:52 PM
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Originally Posted by Iride01
We are simply talking about what the "C" means when on a tire that sometimes might be shown as 622 x 25C by one manufacturer or 700x25C by another. Some only put 622x25 or 700x25.

I don't know how Continental's explanation falls apart for you. They say it means they want their tire on a crochet type rim.

I've never seen a tire with A, B, or D after the width when expressed as above. I have seen 650B and 650C and 700C, but those are true french tire sizing where no info as to the BSD of the tire is given. And that was the crux of the problem with the french sizing that probably brought about the ETRTO standard that later gave way to ISO.


Here is a link to a Schwalbe tire available in "650x28B"
https://www.schwalbetires.com/bike_t...ires/durano_dd

Conti says that the C means to mount any such labelled tire on a crochet type rim, which is contrary to how the 'C' has been used in past decades.
Elsewhere on their site, make no mention of the C being indicative of 'crochet' rims, and say all their tires are only recommended for 'hook' type rims, even for sizes not including the C, and they don't even list XXX x YYC sizes for most of their charts, just ERTO numbers.

From: https://www.continental-tires.com/bi...haracteristics

"Which tire fits to what rim?
For clarification on sizing, all Continental bicycle tires are sized according to the ETRTO (European Tire and Rim Technical Organisation) format: tire width [mm] x tire rim diameter [mm], for example 23-622. This is stated on the sidewall. The internationally recognised ETRTO standard should always be used when in doubt. In general, Continental recommends that bicycle tires only be mounted on hook edge type rims because this type of rim holds the tire more securely, especially with air pressures exceeding 3 bar. An overview of which rim widths fit which tires is available from ETRTO."
Those letters are to indicate rim diameter, not construction. Yes, they can generally be excluded when referring to 700 size wheels because A, B and D are all obsolete, and the system is more confusing than it needs to be, and the ISO standard is superior.

FYI, 'crochet' in French translates exactly to 'hook' in English. The meaning of the letter suffix aside, I think you are trying to draw a distinction where there is none.
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