ksryder

Ironically, as a lapsed journalist and English major, I subscribe to the "language evolves and meanings change" theory of anti-pedantry. Especially the English language, which is a mongrel language and freely appropriates a multitude of other languages and more readily adapts and evolves to changing usage and requirements.

I suppose this seems incongruous with my insistence on using proper units of measurement, but to me there's a difference because a unit such as "mm" has a concrete, unchangeable meaning, whereas "38c" means precisely nothing.

Back to the OP, I have no idea what caused his failure, but my personal opinion is that concerns about wide tires and narrow rims are overstated but not completely without merit, and 15mm seems like a very narrow rim for that tire.

cyccommute 

If you are going to tilt at windmill, make sure you are tilting at real ones. It's 622mm x 38mm. Even the "700C" part is wrong. The "C" part is often thought to mean centimeters but a 700cm tire would be 7 meters (22 feet for the metrically challenged). And it would take a very, very wide tire on a 622mm rim to get to 700 mm...78mm to be exact. That's 3" or what a 29er would use.

Under the old French system, tires were meant to remain the same height so they changed the rim size to fit the height of a tire. A skinny tire was put on a larger rim to maintain the same height as a wider tire put on a smaller diameter rim. The "C" was meant for wider tires so it had a smaller diameter. The system was kind of silly in that you'd have to adjust rim brakes all the time if you wanted to swap out tires for some reason.

ksryder

I agree with him on large tubeless on gravel. I don't agree with his insistence that you don't need puncture protection on gravel, and then when people say "but I got flats" he'll say it's operator error.

My opinion is that it's because he fails to acknowledge that gravel is different everywhere, and that the gravel in the midwest is a lot chunkier and pointier than the gravel I assume he must encounter on a daily basis.

As someone who lives in the midwest, we're used to people on the coasts coming in and telling us what we should be doing and how we're wrong, despite not living here nor having rode bicycles here. It's arrogant.

There is a reason you don't see anyone in the midwest, who is not sponsored, riding Rene Compass Hearse tires on gravel.

(Ted King ran those tires at Dirty Kanza this year and I have it on good authority that he had some punctures even though he never said anything publicly about it.)

ThermionicScott 

The "C" never meant centimeters, though. Anyone who thinks that is being dumb about the metric system.

And it only takes a 39mm tire to get up to 700mm. That seems pretty reasonable to me.

cyccommute 

Most people probably don't know what the "C" stands for. It's a left over from an old, defunct system that is no longer used and hasn't been for decades. The way that we size bicycle tires is an entire mess anyway. Why size them by the size of the tire? It's a dumb system. We should size them by bead diameter and worry about the height and width separately.

ThermionicScott 

I agree for the most part. I tried to switch to using ISO designations exclusively at one point, but it was always a bit awkward when the discussion had already been framed in terms of 26"x1-3/8" or 700C or whatever, so I gave it up.

cyccommute 

I haven't paid attention to what Jan Heine says on much of anything but I don't see why you would need puncture protection on gravel. I've ridden lots and lots and lots of gravel and can't say that I've ever has a puncture due to the sharpness of the actual rocks. Goatheads are a different matter but the rocks themselves don't cause flats in my experience.

I've ridden on gravel at various times in nearly all areas of the US. I can't say that I've noticed "gravel" in the midwest to have sharper points than gravel in the east, south or west. For most of the gravel roads, it's sorted crusher fines and it's going to be about the same material no matter where you ride.

That said, "gravel" roads in the mountainous portions of the west are a lot rougher and aren't really "gravel" so much as rocks. Even there flats due to actual punctures of the rock itself are relatively rare.

WizardOfBoz

cyccommute point in saying that the French system assumed a 700mm (nominally, I think) OD of the wheel, and then adjusted the rim BSD to accommodate different tire widths, is consistent with my understanding. That Nobel Laureate of cycling, Sir Sheldon (here), has curated this info, see below. Note that unless you have a hankerin' for rare stuff, you're talking 700 C and 650 C. I wouldn't say that 700 C hasn't been used for decades. It's (per ksryder's comment) the common tongue way of saying "ISO 622". I suspect it always will be....

Now, if you say ISO 622, are you referring to tubular or clincher tires?

I think that clarity and correctness is the point. So 700 C x 38mm is clear, if not per ISO. But my old 24 inch frame, with the chain at 1 link/inch, is not ISO either and everyone probably understands the terms mean. All sorts of idiosyncracies remain. My favorite is Lowenhertz magneto threads (flank angle of 53°8', not 60°, with flats at top and bottom with width equal to 0.125 times the pitch, and with thread height equal to 0.75 times the pitch - I think Lowenhertz came up with this just to drive the Ultra-rationalist metric Nazis up the wall...).

Francais ISO Size (BSD) Purpose in Life
700 A 642 mm Obsolete
700 B 635 Rod-brake roadsters.
700 C 622 Road bikes, hybrids, "29 inch" MTBs.
700 D 583 Oddball size formerly used on some GT models. 650B tire (584 mm) is slose enough, maybe with wide rim tape.

650 A 590 French version of 26 x 1 3/8; Italian high-performance bikes for smaller riders
650 B 584 French utility bikes, tandems, and loaded-touring bikes; some older Raleigh and Schwinn mountain bikes
650 C 571 Triathlon, time trial, high performance road bikes for smaller riders

cyccommute 

My point is that understanding tires would be a whole lot easier if we used the bead diameter. There would be far less confusion. Your list is only the French side of the equation. There are a lot of other sizes from other countries.

Two notes. The 635mm rim is also the mostly obsolete 27" wheel used on 1980s American road bikes. Curiously (and confusingly) the 622mm rim is called a 28" rim in England and Europe.

The 584mm rim is what is being used for 27.5er (a worse moniker for a class of bikes can't be found).

hokiefyd 

Are you talking about the 27" wheels often used on US-spec bike boom bikes from the '70s and '80s? I thought those were 630mm BSD.

I totally agree with referring to this stuff by BSD (622mm, etc.). Ironically, more people know what a "700c" wheel is than a "622mm" wheel. It's sort of a self-perpetuating problem.

cyccommute 

You are right. Sorry.

The 29er craze has caused all kinds of puzzled looks at my co-op when I tell even experienced volunteers that they have the same wheel diameter as a "700c". Oddly, the 29er tubes keep ending up in the 700C/27" used tube bin.

WizardOfBoz

I agree that the profusion of illogical names is confusing. I feel the same way about wines, especially French and Italian. My thought is that you should state the grape, the general area, the vintage and the maker. Once you learn a bit about wines, you know that a Burgundy is (usually) a red wine made from 100% Pinot Noir grapes. But a white Burgundy is 100% Chardonnay grapes! You get a description of a wine-growing area and its like "The area of FooFoo, as distinct from the more general area of FooFee, grows only Cabdonnay grapes (by law)! The charming exception is the WeeWee vinyard, which makes its wines from grape juice imported from Romania, an arrangement due to the Count of FooFee also being the Duke of Romania in 1783...." I do NOT find stuff like this "charming".

So, I'll raise a glass of Gevrey-Chambertin and think of your point the next time I put a new 27 and a half-er on a wheel...

WizardOfBoz

PS I believe that the 27 inch wheel is an ISO 630, and not 635mm. Or is ISO 635 a 630mm BSD?

Eggman84

Maybe the OP has gone down the rabbit hole of historic tire size and no longer cares why they crashed. But in case they haven't then Lennard Zinn (before any one piles on I will admit he may not be a reliable source of information) just addressed one potential failure mode for tubeless road. See https://www.velonews.com/2019/07/tec...e-power_495710 . I quote "This last week I awoke in a helicopter ride to a hospital. Nobody was around when I crashed, and I have no memory of the crash. Only worrisome part is the front tire [road tubels] was flat with no punctures."

Kapusta

Agreed.

At least “650b” had some history.... and sounds cool.

ThermionicScott 

All this talk of tire sizing reminds me of foreign languages. Some people get really upset that not everyone will speak "their" language, others simply make an effort to be conversant with everyone.