Why have wheels remained the same?

[Brucey]

- are there any smaller tyres than 32x559 ie "skinny" ones?

loads... eg

http://www.acycles.co.uk/mtb-1/tyres-19/tyres-tubetype-62/dimension-26x120-1450,dimension-26x10-582.html

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!

the original reason was (quite reasonably) that you might want to fit wheels with the same OD but different tyre widths into the same frameset, thus you need different rim sizes to accomplish this. As CJ and others have said, originally there was one tyre width for each rim type, but over time that has changed out of all recognition.

As to 'why not choose one?', you might just as well ask why car manufacturers don't all use the same rim/tyre size.

cheers

[pete75]

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.

Probably because the rim diameter was the same as used for tub wheels hence maybe an easy swap for training wheels etc. Remember the 700a b and c designations were for rims and matching wired on tyre sizes not tubs. Until fairly recently everyone raced on tubs. I think it was the mid seventies Mavic Module E rim and matching Michelin Elan tyres which were the first hooked rim beaded tyre combination enabling tyres to take the high pressures suitable for racing. Module E rims were the same width as normal tub rims enabling a straight wheel swap without any brake adjustment.
Racing on tyres rather than tubs wasn't really feasible until the hooked rim was developed so the choice of 700C for racing was made only in the seventies/eighties - probably well after 700A was obsolete.

[JohnW]

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 would we do without him?

We didn't choose to, but we're going to have to

[Cunobelin]

... but there have been a whole load of changes and options for road bikes.

Remember the solid wheels, carbon fibre wheels, bladed spokes, tri spoke wheels, and others

Then there was the temporary fashion for dual wheel sizes with a lowered 24" front wheel



Then we could go into the argument by Thorn about the superiority of 26" wheel size for touring, echoed at least in part by other manufacturers such as Roberts who offer the choice of 26" wheeled models

There is an interesting history from Breton Bikes

[MikeF]

As to 'why not choose one?', you might just as well ask why car manufacturers don't all use the same rim/tyre size.

cheers

But the wheel diameters are standardised in inch (generally) increments, even though profile and widths vary. There aren't say silly in between sizes such as 14" 14.25" and 14.4" wheels, which analogous to the situation with say 650 bike tyres.

[Tigerbiten]

But most 20" wheels are not 20".
My 406 wheels are not 20" but somewhere between 18" and 19" depending on the tyre.
If you want true 20"wheels you need 451 rims, but they're rare.

[Brucey]

As to 'why not choose one?', you might just as well ask why car manufacturers don't all use the same rim/tyre size.

cheers

But the wheel diameters are standardised in inch (generally) increments, even though profile and widths vary. There aren't say silly in between sizes such as 14" 14.25" and 14.4" wheels, which analogous to the situation with say 650 bike tyres.

Ha... if only. There are plenty of metric sized wheel rims out there too; so there are in fact exactly the things you say there are not, which are lots of rims that are between integer inch sizes. If you look at all the diameters and rim widths alone you have many dozens of wheel sizes, and once you allow for offsets and stud patterns, hundreds. And to mount on those rims there are (literally) thousands of different tyres, with different widths, profiles, speed and load ratings. And I'm not even getting into different rim profiles with the same nominal diameter, or different tread compounds, temperature ratings etc.

The popular car tyre sizes are subject to the whims of fashion as much as anything else (remind you of anything?), thus the net result is that for cars that are only 25 years old you can get to the point that you cannot easily buy new tyres in many cases, either easily or at all, even. Which is daft, because functionally, many of these car tyres, wheels etc could be made to be the same as one another for little if any loss in performance... does this sound a familiar story?

cheers

[mjr]

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.

Except they aren't. When looking at new bikes recently, I was actually pleasantly surprised how many bikes have 590 rims. They're not racers or road bikes but upright roadsters from the likes of Pashley (maybe women's only), Bobbin and so on.

[Mark1978]

Many smaller road bikes could benefit from the 650 wheel size. But then it's non standard so would need a different frame geometry, different inner tubes, different tyres etc. These things are all available but in nowhere near the numbers for 700c.

[mjr]

Many smaller road bikes could benefit from the 650 wheel size. But then it's non standard so would need a different frame geometry, different inner tubes, different tyres etc. These things are all available but in nowhere near the numbers for 700c.

As long as they're readily available and the numbers in stock are proportionate to the demand, does it matter? For example, 650A tubes seem to be available in most shops that sell cycle spares except the supermarkets - even the small car spares chains around here still sell them.

Non standard? And what standard would that be, then? They seem OK under ISO 5775

[karlt]

Many smaller road bikes could benefit from the 650 wheel size. But then it's non standard so would need a different frame geometry, different inner tubes, different tyres etc. These things are all available but in nowhere near the numbers for 700c.

Decathlon use them on their smallest frames for their road bikes.

[Brucey]

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.

Except they aren't. When looking at new bikes recently, I was actually pleasantly surprised how many bikes have 590 rims. They're not racers or road bikes but upright roadsters from the likes of Pashley (maybe women's only), Bobbin and so on.

well in the case of Pashley, in some cases they appear to use the same basic frame (and fork?) geometry with 26" wheels (590mm BSD to accept 26 x 1-3/8" tyres) and larger ones such as various ' 28" ' sizes (37-622, 40-635 even). By my reckoning the BB height and mudguard clearance both should vary by an inch or so, but the deep mudguards hide this well, and the BB height is explained as 'a lower bottom bracket for easier mounting' . There is a trail variation (~14mm) with wheel size, but this seems OK and with hub brakes there are no other problems.

Another poster says '650 sizes' as if they are all the same effective diameter; whilst this may have been the case at one point it isn't so any longer. 650A tyres (26 x 1-3/8") still roll at 26" but a 650-23C fitment (23-571) is typically slightly less than 24-1/2" outside diameter, i.e. about 2" smaller than a 23-622 fitment.

cheers

[[XAP]Bob]

Lower BB for easier mounting is fine - that's a consequence of smaller wheels on a smaller frame, and is probably appropriate for a smaller person.

Of course it needs shorter cranks to ensure that the risk of pedal strike isn't increased...

[ChrisButch]

Perhaps another factor here is that smaller frame clearances and lower tolerances in other components mean that nowadays it's rarely possible to change the wheel size without changing the bike. That wasn't always so. I remember circa 1980 being able to switch from 27 x 1.25" to 700c on both my then solo and a tandem without needing to change anything else, not even the brakes - since the Mafac cantilevers on both bikes had enough adjustment to work perfectly well on both. Difficult to imagine being able to do something similar with a 2015 bike.

[Dave W]

Good point, My Landescape Tandem takes either 26" mountain bike wheels or 700c. V brakes or Disc brakes.