Why have wheels remained the same?

[Brucey]

....Why haven't they started fiddling about with road cycle wheels?

a) Because (in a road race) it would give you a severe competitive disadvantage; it is a very good idea to be running the same size spare wheels as everyone else; if you don't then you can't use neutral service facilities.

b) Because they are not allowed to. UCI regs mandate that the overall wheel diameter should be between 55cm and 70cm.

55cm isn't small enough to build a really aero bike (although it would allow even smaller frames more easily) and 70cm isn't much larger than the presently used wheels are. Possibly anything over ~30-something mm tyre section on a 622 rim is liable to be over 70cm overall and thus illegal, even now.

cheers

[Dave W]

Racing aside - why have there been so few variations?
I find it odd that a 700c wheel is deemed the best size to race on and the best size to tour on for people from five feet tall to seven feet tall. I don't know if different sizes are even necessary. Just find it strange that manufacturers haven't fiddled about much with them over the years considering millions upon millions of cyclists don't race.

[RickH]

It would be relatively easy for bike/wheel manufacturers to vary wheel sizes but, and it is a big but (who are you saying has a big butt? ), you have to persuade tyre manufacturers to make a decent range (or even any) in that additional size. Without tyres you're not going very far!

Rick.

[Bicycler]

Of course the '29er's' are actually running 700c wheels just with bigger tyres. 20, 24, 26, 27, 28, 29" all refer to an over tyre diameter not the wheel size which is the Ertro figure. So 28 and 29 are both 622's for instance.

and, obviously 28" and 29" refer to wheels with a smaller diameter than 27" ones Examples like that and the way so many think that 29er and 700c are different sizes show that we really need rid of this antiquated nomenclature.

[Brucey]

Racing aside - why have there been so few variations?
I find it odd that a 700c wheel is deemed the best size to race on and the best size to tour on for people from five feet tall to seven feet tall. I don't know if different sizes are even necessary. Just find it strange that manufacturers haven't fiddled about much with them over the years considering millions upon millions of cyclists don't race.

Racing is easily explained and has been in an earlier post.

Re other cycling; you may be forgetting a few things;

1) the most common wheel size was, for years, 26" (in 590 and 597 form). You can fit most adults to a 26" wheeled bike.

2) the modern approach has been to use the 26" MTB sized wheel; the 559 rim allows (with skinny tyres) nearly all adults to be fitted to a large-wheeled bike.

3) most populations are getting taller; this means that (even though they are too big for some folk, especially many women) more people can be fitted to a 700C wheeled bike than in previous decades.

For as long as the safety bicycle has existed, people have sought the largest wheels they can manage because it invariably improves ride quality and lowers rolling resistance, all else being equal. Thus with this mindset (rightly or wrongly) in place, smaller wheels become relegated to folders, kid's bikes, and oddball ones like moultons. When you are growing up it is a rite of passage to get a 'proper bike' and once on one, there is usually no 'going back' for a long while.

cheers

[ChrisButch]

Remained the same? Perhaps 'recently become the same' would be more accurate.The '700c hegemony' is relatively recent, dating from the late 1970s. Before the general move to that metric size, imperial sizing in 26", 27" and even 28" was widespread. Generally speaking, 26" was preferred for touring and leisure riding, 27" for racing. There were fewer 28", but they were still used on quite a few utility bikes. The various versions of 650 were also widespread, especially on the continent, and never entirely disappeared, their cause kept alive by some framebuilders such as Thorn, some tandem builders and some TT specialists.

[Brucey]

'650 sizes' are 26" sizes.

650A is 26 x 1-3/8" is ~35-590 and 650B is 26 x 1-1/2" is ~40-584.

The practical exceptions to this are modern MTB tyres, which fit to 584 rims, but are larger than 26" outside diameter, and skinny 571 BSD fitments. Tyres often referred to as '650C' are nothing of the sort, strictly speaking. 650C is the same thing as ~47-571 or 26 x 1-3/4". 23-571 is not a '650C' size, it just happens to go onto that rim. Similarly a 23-622 is strictly speaking not a 700C size, either; it just goes onto the same diameter rim.

cheers

[Bicycler]

I sold on ebay the narrow slick tyres which had been on the old mountain bike I bought earlier this year. A potential buyer got agitated that I didn't give a simple yes or no when he asked "will these fit my bike with 26 inch tyres?". It really isn't made easy for people to understand.

[Bicycler]

Out of interest, why did the wide 700C become the racing standard, not the narrow 700A?

[pete75]

Out of interest, why did the wide 700C become the racing standard, not the narrow 700A?

The 700C refers to diameter. 700C rims are available in all sorts of widths certainly narrow enough to take an 18mm wide tyre. In any case the narrowest tyre is often not the one with the lowest rolling resistance for most riders. Rolling resistance is increased by tyre deformation on contact with the road. A wider tyre at the same pressure deforms less so may be faster for the same rider.
However for many years almost all road racers and testers used tubs and most pros still do. These almost all came to fit 700c wheels. In olden days - 1970s - most English club riders had 27" wheels on their training/club run bikes and 700C on their tub equipped competition machines.

[Bicycler]

My understanding of the French designation was that the number related to the external diameter of the tyre in mm and the letter referred to the width, with A being the narrowest and C being the widest. I think they required different diameter wheels to make the external diameter the same with different profiles of tyres, hence 700A and C (I assume there were also Bs) have different bead diameters. This was before our time Pete. I accept that the width distinction was lost and 700C designation came to include some very narrow tyres (as Brucey notes above with 650C).

Anyway, my question was why the historically wider 700C was chosen over the historically narrower 700A as the wheel size for racing on narrower tyres.

[JohnW]

Just wondered why road bike wheels don't seem to be a target for manufacturing companies for road bikes?
Mountain bikes have gone through three different diameters overnight with the middle size of 650b being the current No1 hit when in reality it makes little difference to the end user.
Road bikes seem to have always been the same size to me, with the exception of small wheeled folders. Maybe a slight change when going from imperial to metric.

Why haven't they started fiddling about with road cycle wheels?

They're ok as they are - if it's not broken, don't mend it.

[Bicycler]

I found this post by CJ on an old thread. Which explains the French sizing system and discusses the 700A/700C issue: viewtopic.php?f=5&t=34426&p=273129&hilit=700C#p273129

700C is what the French chose to call 28×1¾ (or 1 5/8, back then they weren't all that precise), because - being French - they couldn't abide inches. But 28 of them was near enough 700mm and tyre widths were coded A, B or C according to how fat they were: i.e. 1 3/8, 1½ and 1¾ respectively. The pneumatic tyre was invented in Britain of course, so everything originated in inches where the Dunlop factory produced both tyres and rims. Thus we generally kept the outer diameter of the wheel constant and offered a choice of tyre sections by tweaking the bead diameter of the rim.

Over in France, tyres and rims were NOT usually made in the same factory, so as roads and tyre technology improved to the extent that tyres could be made slimmer, they made them fit existing rims - never mind that this reduced the overall wheel diameter a bit. If that tyre proved popular the rim manufacturer would reduce the width of his product also, but obviously keep the same bead diameter. By this evolutionary mechanism, the original big fat 700C got a whole lot slimmer, ultimately giving rise to tyre of 32mm section or even less. That's 1¼ inches: even slimmer than with "A" - never mind width "C"! To describe these evolved sizes the French inserted the actual tyre section, in mm, between the 700 and the C thus: 700×32C.

Since 700A became extinct and 700B is nowadays common only on roadster bikes in India and Holland, which isn't something "real cyclists" tend to know much about. So it's commonplace for otherwise well-informed riders to omit, mangle, misplace and/or wrongly attribute the purpose of that final letter "C". If I had a pound for every time I've read about 700cc tyres!

Such negligence leads to a whole lot more actual confusion in the nominally 26in or 650 sizes, since all of them remain in existence, in various more or less evolved stages, in various parts of the world. 26×1 3/8 = 650A, has a bead diameter of 590mm and used to the one size of tyre you could rely upon finding everywhere in the world. Nowadays that'll be the 26in mountain-bike size, which doesn't fit into the ABC series at all but evolved separately from an American 2in balloon tyre (resulting in a 559mm bead, since that's what you get from subtracting twice 2in from 26in) and is distinguished from European sizes by the subtlety of expressing it's actual width in decimal inches instead of fractions. Thus 26×1.5 is nothing at all like 26×1½ = 650B = 584mm bead and still a popular size in France and Japan. Then you have 26×1¾ = 650C = 571mm, which underwent a similar evolution to 700C and nowadays exists only in its narrowest forms.

It is curious that 700C and 650C, the widest two sizes in the ABC series, both gave rise to the narrowest tyres in present day use. I think the reason for that is they're both very old sizes, probably dating back to the invention of the pneumatic tyre, way before the ABC metrication, at a time when 1¾ inches was as slim as a tyre could be made and when the method of attachment to a rim had not been settled upon. Back then: wired-on and sew-up (tubular) tyres existed side-by-side in the popular sizes of 26×1¾ and 28×1¾ and for some reason, as the sew-ups got slimmer they always kept the same rim size. It might have been because racing brakes acted on the sides of the rim rather than pulling up on the spokeface, whatever: the orginal "C" sized fat tyres evolved side-by-side, both getting slimmer as the state of the art improved, to ensure that racers on the continent at least, always had a choice between wired-on or sew-up.

What would we do without him?

[Brucey]

...Anyway, my question was why the historically wider 700C was chosen over the historically narrower 700A as the wheel size for racing on narrower tyres.

Good question. I think I've only ever seen maybe one bike ever with 700A (642mm BSD) rims. Wikipedia describes 'most old English sports bikes' as having this fitting which I find hard to believe. I note with interest that the 630mm BSD size (27 x 1-1/4") was never given an allocation under the old French system (which goes straight from 635 (700B) to 622 (700C)), even though it was for many years by far the most common size on British made sports and touring bikes.

One of the first 'proper bikes' I had was a 1976/77 Dawes Mirage which was fitted with 27" wheels (630mm BSD) with Mavic E2 rims shod with 23mm width tyres. A few years later the same kind of bike would have been for sure fitted with 622mm BSD rims, and in the meantime my brake blocks were going up and down like nobody's business whenever I swapped in my sprint wheels.

The 'excuse' I've heard for sprint wheels being the same brake drop as 622mm BSD rims is that it allowed easy swaps between racing wheels and daily use/training wheels. The thing is that this would mean that 700C was a popular size (which I guess I can believe) and that racing bikes were able to use some kind of wire-on tyre on such rims, such that they would work OK in a racing frame.

I struggle with the second and third bits, I really do; I don't see much evidence that there were skinny rims and tyres that were like tubs, but OK to train on. Maybe it all goes back further than that, but I look at pictures of continental racers and racing bikes from the 1940s and 1950s and I see machines that would not easily accommodate a true 700C (~40-622) tyre under the brakes, and I don't see loads of photos of people training on HPs; dedicated racers seemed to me to use sprints and tubs for training too.

Certainly that was the case when I started racing, although many British riders who used their bikes daily would run 27" wheels normally (commuting and winter training) and then run sprints when racing, putting up with the dreadfully 'gappy' look that resulted when in racing mode on a single frameset, or using a whole different bike for racing. I gather that a previous generation may have swapped between 26 x 1-1/4" HPs and sprints in the same frame which made a bit more sense in a way, because the overall diameters were about the same, even if the brake drops were way off one another.

Interestingly I think it was about 1976 that Mavic first produced genuinely skinny 622mm HP rim types ('Module E' and 'Module E2'). Prior to that I'm not sure such things were commonplace, if they existed at all. Arguably only once such rims became available did the whole idea of having 'HP training wheels' (that were a straight swap with sprints in your racing bike) become truly viable.

Maybe folk who were racing in the 1960s and 1950s can comment further; I remember asking 'why?' when I started racing and I didn't get a very satisfactory answer...

cheers

[MikeF]

Racing aside - why have there been so few variations?
I find it odd that a 700c wheel is deemed the best size to race on and the best size to tour on for people from five feet tall to seven feet tall. I don't know if different sizes are even necessary. Just find it strange that manufacturers haven't fiddled about much with them over the years considering millions upon millions of cyclists don't race.

Racing is easily explained and has been in an earlier post.

Re other cycling; you may be forgetting a few things;

1) the most common wheel size was, for years, 26" (in 590 and 597 form). You can fit most adults to a 26" wheeled bike.

2) the modern approach has been to use the 26" MTB sized wheel; the 559 rim allows (with skinny tyres) nearly all adults to be fitted to a large-wheeled bike.

3) most populations are getting taller; this means that (even though they are too big for some folk, especially many women) more people can be fitted to a 700C wheeled bike than in previous decades.

For as long as the safety bicycle has existed, people have sought the largest wheels they can manage because it invariably improves ride quality and lowers rolling resistance, all else being equal. Thus with this mindset (rightly or wrongly) in place, smaller wheels become relegated to folders, kid's bikes, and oddball ones like moultons. When you are growing up it is a rite of passage to get a 'proper bike' and once on one, there is usually no 'going back' for a long while.

cheers

I agree with Dave W and that was the point I was trying to make earlier. Different frame sizes ought to have different size wheels. However it seems all adult bikes are built around 622 rims with frame compromises to make them fit.

Maybe three sizes would accommodate a wide range of adults and "pre adults" and reduce this "bike fit" problem. If the aim is to encourage as many people to cycle then the one size fits all approach won't work. Few bike manufacturers seem to have come to this conclusion though, although there are some road bikes with 650c wheels often marketed as "Junior" bikes which implies they are not the "real thing".

Today the situation seems to be:-
For 622 rims there is a huge choice of tyres in sizes 18-47 (or more?). For the now common size of 559 rims smaller tyres and rims are either unobtainable or not readily available - are there any smaller tyres than 32x559 ie "skinny" ones?
Between those two sizes of tyres there is the great mix up of 650 sizes, ranging from 571 to 590 rims. I'm puzzled why manufacturers haven't standardized on a rim size - 571 seems only for small road tyres - 584 for off road tyres and so on!