FordTrax

I ordered a carbon fork with a 15mm TA - disc brake. As was mentioned here in an earlier post there are a lot of wheelsets that have a 15mm TA front wheel. I plan to run between a 38-42mm tire on this bike, so I was planning between a 19mm-22mm internal width wheel. Since this is an "allroad"/touring frame I want some solid wheels so I was thinking minimum 32 spokes.

Are the 29ER wheels made with heavier gauge rims, bearings, or heavier spokes than 700c wheels? Or are they basically the same with just wider widths available in 29ER?

It seems like I might get more wheelset for my money with 29ER. Which would you go with if you were doing this build?

wschruba

700c/29" is six of one/half-dozen of the other.

It's driven by an industry who can't decide how they want to market things, so generally speaking, inches refer to mountain bikes, French sizing to everything else. Mechanics use ETRTO sizes, as it leaves no room for miscommunication. 622, for those sizes, for what it's worth.

There may be differences between a 100mm wide, 15mm diameter axle for a road vs mountain bike, but the only significant one, aside from fashion (see: low spoke counts, weird spoking patterns), is a wider rim on the mountain bike vs the road bike.

branko_76 

So 700C is the same as 29" but both are really 622....reminds me of this Seinfeld episode...

Stadjer

When my new tyre fell over the rim, I found out that the classic inch sizes refer to the outer circumference of the wheel, including the tyre. So a classic 28" rim is about 27". ETRTO is the actual rim size and the inner circumference of the tyre.

Elvo

29er comes in many different flavors - endurance, XC, DH, all mountain, etc as evidenced by DT Swiss's 7 or so wheel designations so you can get a superlight carbon XC wheel that rivals the lightest factory road wheels or some super beefy high flange downhill wheel. I think for your application, you can't go wrong with a decent XC wheelset.

Oso Polar

This is a great picture! Any idea why 37-622 is 700x35c? Both seem to be measuring the tire width the same way but getting a different answer!

fietsbob

3 systems ETRTO, Fractional/inch, and French.

Variation in tires.. and companies make 37, others a 35..
[1 & 5/8" is not a metric measurement]


for a 2" tire a 29er rim is wider..

On the course in Switzerland, for the world championship MTB race,
everyone was on 29ers..






.....

Broctoon

This.

When they call a rim 29-er, they're marketing it to mountain bikers, and 700c, to roadies. They're the same diameter. The important differences are the width (which can vary through a pretty wide range, according to intended use), and the rim's shape, material, etc. I wish all manufacturers and all cycling disciplines would go to a universal sizing standard, preferably ETRTO.

CO_Steve

Won't most 29er wheelsets have 135mm rear spacing where 700c will likely be 130mm?

trailangel

Most 29ers are now 142mm and 148mm "boost" spacing. It's changing all the time.

Sy Reene

Good question.. I've never really seen a satisfactory answer to this. Vittoria even shows (and only for this specific size) the same oddity for their tires, eg. Randonneur Pro

Stadjer

Probably because it's to determine which tyre fits, not to determine the size of the rim. Slightly wider or narrower tyres will fit the same rim. There was a huge table beneath this picture with all kinds of sizes and more Dutch words, so I didn't copy that. A C/P of a relevant part didn't work either so here is the link. The relevant part starts at ETRO sizes 35-622.

The 'Stadsfiets' is the one from the picture and that has been the most regular upright Dutch bike with those tyres for decades. The regular upright French bikes are usually a bit flimsier with narrower tyres, just as the sportier Dutch bikes above the stadsfiets. So the 700x35 C fits as a replacement for a 35-622 too. The next French size, 38, might not fit if you replace a 1 3/8 because the fender stays are in the way. So I guess the table and the picture are playing it safe, it tells what does fit and not what might fit. I recently put on 47-622 to replace the 1 3/8 but simular bikes might have less clearance and an LBS wouldn't think I left enough clearance anyway. The width in both ETRTO and French is the width between the walls of a tyre full of air, not the width of the bead.

Appearantly the C in French stands for 'jante a croche', which as I understand it is a 'hooked rim', there are also B's but I have no idea what that stands for. Logically the height of all French tyres should be about the same at 700 - 622 = 78mm, or 3 inch. That's not right, so the 700 is probably about the necessary space in the frame, including fenders and some room to tension the chain. Initially I assumed the reason those old sizes use the outer circumference of the wheel including the tyre was to calculate the right gear ratio's for the desired metres of development, but that can't be the case with the French sizes. At least the Dutch (copied from the English) sizes give the heigth of the tyre also. It's probably just typically French: they invented the metric system but lost interest afterwards, didn't bother with it's precision and just used a nice round number.

My conclusion is that ETRTO works very well as long as you or a webshop don't let the other sizes interfere, and it works together with a tape measure contrary to the others.

cyccommute 

While the hubs may be different, it's the rim that carries the size designation. A 700C (622mm ISO) rim is the same size as a 29er rim. The tires for both are interchangeable. The wider 29er may not fit in a road frame but it's the same size of tire. Hub width has nothing to do with the rim size. There are plenty of 135mm OLD bicycles using 700C rims. Touring bikes, for example, have used the mountain bike width hub for a long time. Crossbikes and, I suspect, gravel bikes as well. Some of the gravel bikes may even use the "Boost" spacing or will in the near future.

I'm not sure that the C stands for hooked rim. 700C tires were available in the US long before hooked rims were prevalent. The 700B, however, is (yet) another wheel size. According to Sheldon Brown, it is a 635mm rim that was called a 28" and was prevalent on "English, Dutch, Chinese, Indian Rod-brake roadsters".

The English, as well as others, call the current 622mm rim a '28" wheel' which is probably just a hold over from the old 635mm rim. I've run across similar ideas when referring to the 27" wheel here in the US. Someone at a bike shop once tried to tell me that a 700C (622mm ISO) was the same as a 27" (630mm ISO). They aren't.

CO_Steve

My reading of the OPs question was that he was doing a build and wondered what type of wheelset to look for. Yes, the rims/tire are the same size but shopping for a wheelset rear spacing is something important to get right.

DrIsotope

I have two wheelsets for my CX bike-- one is my (now) "road" set, and the other is a mish-mash Crank Brothers set, a front Iodine and a rear Cobalt. I've probably put 6 or 7 thousand road (tubeless) miles on those CB wheels.

The first wheelset I bought was WTB i23 hoops on Deore XT hubs-- sold as an "MTB" wheelset. Cheaper, thanks to that-- a "road" set with the same hubs cost about 50% more.

Elvo

700C and 29er disc will almost always be 135mm QR or 142mm TA or boost or super boost +

well biked

Off topic a little, but regarding the "700c" designation, the "c" was originally a width designation. A, B, C, and D designations were used, with A being narrowest, D being the widest. Sheldon explains in this paragraph:

French sizes:

In the French system, the first number is the nominal outside diameter in mm, followed by a letter code for the width: "A" is narrow, "D" is wide. The letter codes no longer correspond to the tire width, since narrow tires are often made for rim sizes that originally took wide tires; for example, 700 C was originally a wide size, but now is available in very narrow widths, with actual outside diameters as small as 660 mm.

wschruba

To expand on this: 700 (and 650) told you the outside diameter of the inflated tire. As noted, A, B, C, D were progressively larger tires. A 700A tire was the same outside diameter as a 700D, but much smaller width-wise (and ergo, the rim would be larger than the 700D). The last vestige of this in our modern system is 650B/650C (B being used on smaller-wheel bikes for smaller riders, and sometimes found on Randonneur bikes, while C exists mostly on time-trial bicycles). It is not hard to see, then, why one would prefer the modern system of [BSD]-[Tire Width].

fietsbob

Yes in the category 600, 650, 700 , etc,
the overall diameter is constant,

as the tire is fatter, wider& taller,
the rim (bead seat) diameter is smaller.

Stadjer

Me neither, I got it from French wikipedia.
I've got a Dutch rodbrake roadster which was origanlly fitted with 28x1 3/8 x 1 5/8, but it's only 40 years old and older roadsters often had wider tyres, so that makes sense. But it doesn't make sense to me when it comes to the diameter. I've never seen a bigger rim on a Dutch roadster than a 622, that has been the top size for ages. I might just not have noticed, but that would surprise me. I've owned an older rod brake roadster, probably pre war, and I'm tall and never liked the proportions of the taller bikes with the 28 inch wheels.

A 622 rim with an 1 5/8" high tire would make a 663,275 mm outer diameter, and that's 26,1 inch. A 635 with a 1 5/8 tyre would still be well short of a 28 inch outer diameter, with 26,6 inch. So it still makes no sense. The only thing that comes close to 28"is the length of the front fork x2, which would make at least some sense. .

Still I don't believe a 700C tyre that is supposed to fit on a so called 28" rim or a 622 or 635 rim has an outer diameter of 700mm, the difference is just too big for a tyre to fill. Maybe I went wrong somewhere, but I don't believe that if you measure the diameter of a 700C it will be 700 mm. Maybe the French just converted the English 28", which isn't 28 inch, to the metric system?

cyccommute 

Perhaps Dutch bikes shouldn't be included in the list. The 28" wheel was on the Raleigh Roadster as well as some other English bikes. From what I can tell, they were pre-WWII to post WWII (mid-50s?). Harris Cyclery still sells them and says they are for brands like " Dunelt, Raleigh, Rudge, Humber, Phillips."


No one ever said that bicycle tire sizes were anything but confusing. They are all supposed to be the size of the tire's outside diameter but, as you pointed out, that doesn't add up. I'm trying to move away from calling tires by their "size" and referring to the rim diameter instead. It's still confusing but less so then going by the outside diameter of some "standard" tire.

On a side note, Oregon passed a bicycle excise tax law that is supposed to generate money for bicycle projects in Oregon. It's a $15 tax on new bikes sales on bicycles that have "26-inch or larger wheels". If you do the math, like you have, the only bike that they could collect tax on is a Coker Monster Cycle. The law says "wheel", not tire. A 700C wheel is only 24.5" and as long as you keep the tire size under 38mm, you aren't being a bike with wheels and tires larger than 26"

Stadjer

There's been little difference between English and Dutch roadsters, all the Raleighs I've seen were about the same size with the same size wheels and tyres. It's mostly copied and changed English designs, and the sizes were copied too, including the inches, which are only used in case of rims and tyres.

I guess it's best considered a name for a certain tyre/rim with a certain size rather than a size itself. That's why I believe ETRTO is a big improvement.

Cool. Maybe it's laws like that have set industry standards. I like those monster wheels, looks much better than a tall frame on regular wheels, there should be a market for them here.

Leebo

It's a mess. Fronts are now 110 and 150 for fat bikes. My " old" 2013 bike is 100 front, 142 rear. Now boost is 110 front, 148 rear with some at 150 and some rears also at 157. Yikes. Oh and rear for fat bikes can be 170, 190 and 197. Hmmm.