MattyP1985 wrote:Stupid question; will 700C wheels be suitable for a 28 inch wheel frame? I assume it might require brakes with extended arms?
630 mm / 27 inch Clincher for older road bikes
This is the size used on most "10 speed" bikes sold in the U.S. before the early 1980s.
Click here for 630 mm/27 inch Rims
622 mm / 700C / 29 inch
This is the size used on modern "road" and touring bikes, most hybrids. It is also sometimes known as "29 inch" for mountain bike use. In northern Europe, this size sometimes called "28 inch."
The Duckmeister wrote:Going back to the really dark ages, 28" was actually a common wheel size. With a 635mm rim diameter, they're bigger than a 27" rim (630mm) and 700c (622mm).
barefoot wrote:The Duckmeister wrote:Going back to the really dark ages, 28" was actually a common wheel size. With a 635mm rim diameter, they're bigger than a 27" rim (630mm) and 700c (622mm).
That's true of English bikes, using 28 x 1 1/2" wheels.
But old Australian bikes used yet another 28" size - 28 x 1 3/8", which used 642mm rims. These were rare enough in the rest of the world that Sheldon doesn't even mention them.
A bit of head scratching led me to the realisation that they all correspond to the lesser-used French 700-series sizes:
700A = 642mm
700B = 635mm
700C = 622mm
For those not familiar with the history, these sizes were all designed to give a rolling diameter of 700mm, using different tyre/rim combinations. "A" tyres were narrow, "C" tyres were fat.
For whatever reason, Europe standardised on the 622mm rim that was meant for fat "C"-section tyres, then started making different sized tyres for it so it no longer rolled on a 700mm diameter.
For whatever other reason, England standardised on the 635mm 700B rim, but called 28" because nobody understood that foreign measuring system.
And Australia standardised on the 642mm rim, also called 28", just to be confusing.
In some parts of Asia, 622mm rims are also called 28".
I guess 28" is pretty close to 700mm... which is about how big they are when fitted with the original French-standard tyres... which they rarely if ever are.
Don't get me started on the new wisdom of calling 622mm MTB rims 29"...
I know all this because I recently found a (now understood to be) 1950s bike in hard rubbish, with 642mm rims. You can still get the 642mm tyres if you search hard enough... but one of my rims is rusted out, and they're completely unavailable. Luckily, though, this old girl has no rim brakes, so I can convert it from 700A to old-school fat-tyre 700C without changing the rolling diameter .
As best I can figure out (the interweb is very vague on this), A-profile tyres were about 32mm (~1 3/8) and C-profile tyres were about 44mm (~1 3/4"). I have clearance for about 48mm tyres, so I'll play it safe and go for 700 x 40C tyres.
Anyway... how this relates to this old frame... if it really is an old Australian 28"er, the rims were quite a bit bigger than anything you can get today, and you'll have a hard time getting calipers to reach far enough to contact 700c rims. Or even 27" rims. But you might be lucky. The other option is to go for a coaster brake. Or brakeless fixie. Then you can run whatever rim/tyre combo you like to get somewhere near the right rolling diameter.
sneezy wrote:just to add to the mix...I have an old bike with 700D rims
The Duckmeister wrote:Going back to the really dark ages, 28" was actually a common wheel size. With a 635mm rim diameter, they're bigger than a 27" rim (630mm) and 700c (622mm). If the frame was actually built for 28" wheels, you will not find brakes with a long enough reach for 700c. However if it was built for 27" you should be able to get brakes with enough reach to suit the smaller wheels.
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