Tyre sizes
- Thread starter mrcpea
- Start date
This is a nightmare, according Sheldon Brown some tyres marked 28" are the same or similar to 700 size tyres, others are not.
The ISO/ERTO system is the most consistent system. It measures the bead seat, i.e. where the inside edge of the tyre connects with the wheel rim when the tyre is mounted.
If the diameter of the rim bead seat (measured where the inside edge of the tyre meets the rim) measures the same as the inside diameter of the tyre, the tyre is the right size.
Is that clear? Not sure it makes sense now I've written it down.
The ISO/ERTO system is the most consistent system. It measures the bead seat, i.e. where the inside edge of the tyre connects with the wheel rim when the tyre is mounted.
If the diameter of the rim bead seat (measured where the inside edge of the tyre meets the rim) measures the same as the inside diameter of the tyre, the tyre is the right size.
Is that clear? Not sure it makes sense now I've written it down.
Rainbowdave
Dirt Disciple
You're right that 27x1 1/4 is bigger than 700c (which is 28x1 5/8 if my memory serves me correct) 28x1 1/2 is bigger than both.
ian.allen2
Retro Guru
Saw this on wikipedia
700C road bicycle wheels / ISO 622mm
700C front wheel
Plastic BMX wheel
Touring, race, and cyclo-cross bicycles may have vastly different design goals for their wheels. The lightest possible weight and optimum aerodynamic performance are beneficial for road bicycles, while for cyclo-cross strength gains importance, and for touring bicycles strength becomes even more important. However this diameter of rim, identical in diameter to the "29er" rim, is by far the most common on these styles of bicycles. It rolls more easily than smaller diameter tires. Road wheels may be designed for tubular or clincher tires, commonly referred to as "700C" tires.
Mountain bike wheels
A 29" and 26" mountain bike wheel
Mountain bike wheels are described by the approximate outer diameter of the wheel plus a wide, ~2 inch tire.
26 inch / ISO 559mm
26-inch clincher tires (with inner tubes) are the most common wheel size for mountain bikes. This tradition was started initially because the early mountain bike pioneers procured the wheels for their early bikes from American-made bicycles rather than the larger European standards in use. The typical 26-inch rim has a diameter of 559 mm (22.0") and an outside tire diameter of about 26.2" (665 mm).
27.5 inch / ISO 584mm / 650B
Main article: 27.5 Mountain bike
27.5-inch mountain bike wheels (which some also refer to as 650B) use a rim that has a diameter of 584 mm (23.0") with wide, knobby tires (~27.5 x 2.3 / ISO 58-584) are approximately the midway point between the 26-inch (ISO-559mm) and the 29-inch (ISO-622mm) standards. They carry some of the advantages of both formats, with a smoother ride than a 26 inch wheel and more stiffness and durability than a 29" wheel. As 27.5-inch wheels have just started to be embraced by larger manufacturers, one of the primary disadvantages has been a reduced selection of compatible frames and forks. However, an increased availability of 27.5-inch forks, wheels, tires and tubes is expected in 2013.
29 inch / ISO 622mm / 700C
Main article: 29er (bicycle)
“29-inch wheels”, which also conform to the popular 700C (622 mm diameter clincher) wheel standard are becoming more popular for not only cyclocross bikes but also cross-country mountain bikes. Their rim diameter of 622 mm (~24.5 inch) is identical to most road, hybrid, and touring bicycle wheels, but are typically reinforced for greater durability in off-road riding. The average 29-inch mountain bike tire has an outside diameter of about 28.5" (724 mm).
700C road bicycle wheels / ISO 622mm
700C front wheel
Plastic BMX wheel
Touring, race, and cyclo-cross bicycles may have vastly different design goals for their wheels. The lightest possible weight and optimum aerodynamic performance are beneficial for road bicycles, while for cyclo-cross strength gains importance, and for touring bicycles strength becomes even more important. However this diameter of rim, identical in diameter to the "29er" rim, is by far the most common on these styles of bicycles. It rolls more easily than smaller diameter tires. Road wheels may be designed for tubular or clincher tires, commonly referred to as "700C" tires.
Mountain bike wheels
A 29" and 26" mountain bike wheel
Mountain bike wheels are described by the approximate outer diameter of the wheel plus a wide, ~2 inch tire.
26 inch / ISO 559mm
26-inch clincher tires (with inner tubes) are the most common wheel size for mountain bikes. This tradition was started initially because the early mountain bike pioneers procured the wheels for their early bikes from American-made bicycles rather than the larger European standards in use. The typical 26-inch rim has a diameter of 559 mm (22.0") and an outside tire diameter of about 26.2" (665 mm).
27.5 inch / ISO 584mm / 650B
Main article: 27.5 Mountain bike
27.5-inch mountain bike wheels (which some also refer to as 650B) use a rim that has a diameter of 584 mm (23.0") with wide, knobby tires (~27.5 x 2.3 / ISO 58-584) are approximately the midway point between the 26-inch (ISO-559mm) and the 29-inch (ISO-622mm) standards. They carry some of the advantages of both formats, with a smoother ride than a 26 inch wheel and more stiffness and durability than a 29" wheel. As 27.5-inch wheels have just started to be embraced by larger manufacturers, one of the primary disadvantages has been a reduced selection of compatible frames and forks. However, an increased availability of 27.5-inch forks, wheels, tires and tubes is expected in 2013.
29 inch / ISO 622mm / 700C
Main article: 29er (bicycle)
“29-inch wheels”, which also conform to the popular 700C (622 mm diameter clincher) wheel standard are becoming more popular for not only cyclocross bikes but also cross-country mountain bikes. Their rim diameter of 622 mm (~24.5 inch) is identical to most road, hybrid, and touring bicycle wheels, but are typically reinforced for greater durability in off-road riding. The average 29-inch mountain bike tire has an outside diameter of about 28.5" (724 mm).
Rainbowdave
Dirt Disciple
That's definitely the technical way!
I like the fact that this new size of MTB tyre means I can run knoblies on my 40's French bike and take to the woods for the winter.
I like the fact that this new size of MTB tyre means I can run knoblies on my 40's French bike and take to the woods for the winter.
ian.allen2
Retro Guru
Sounds good. My first bike was a Hercules Balmoral and went through many guises. I remember when knobbly tyres came out in the 70's and were 50p each. We bought some and there was nowhere we could not go. We even used to go over logs and rocks before the program 'Kick Start' started on the tv.
Rainbowdave
Dirt Disciple
I never knew nobly 26x1 3/8 tyres exsisted till a mates da showed me his old 'tracker' frame and bits from the end of the 70s/beginning of the 80's. still never found a set to place my own.
Any old photos sir?
Any old photos sir?
ian.allen2
Retro Guru
Sorry, no photos. I last rode a bike properly when I was around 16 - 17 years old. I never had any pics taken of any of my bikes. I think the knoblies I had came out when I was about 14 yrs old, back in '72. The tytres were just like speedway bike tyres with nobbles on. No pattern to them. They were 26 x 1 3/8 and very cheap from our lbs. They seemed poorly made compared to the michelin tyres which were common in those days. But, we used to do a lot of back wheel skidding. No such thing as slicks in them days unless the tread was worn and then the local bobby was on your back. It was bad enough being chased by the old bill for no lights or reflectors or brakes. I wore a few trainers through on on the sole stopping my bike by putting my foot on the front wheel just behind the forks at the top.
