700c, When??
03-07-09 | 04:53 AM
#26
Senior Member
Joined: Nov 2004
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While I do not have a definitive response to the OP’s questions, I would like to make some observations regarding the various responses, most of which are correct. Unless otherwise stated, all my statements are made in reference to clinchers, as opposed to tubulars..
700C is simply a metric designation for a tire with a nominal outer diameter of 700mm and a bead seat diameter of 622mm. Equivalent, compatible tires exist in imperial sizes. These imperial tires all have a nominal outside diameter of 28”, though there are variations of bead seat diameters among 28” tires, so not all 28” tires are 700C compatible. Basically, the same size tire exists in both metric and imperial measurements.
The French and English were the original leaders in the bicycle industry and developed separate standards around metric and imperial measurement, respectively. A 622mm bead seat diameter is equivalent to 24.49". This is so close to 24.5", that I suspect the English 28" tire, with a 25.5 bead seat diameter, is the actual origin for the size. If the French had originated the size, I would think that a more convenient bead seat, such as 620mm or 625mm, would have been selected. Most likely, the French simply re-engineered the imperial tire to a metric measurement, so it could be understood in France and other nations where the population and bicycle industry employed metric standards (i.e. Belgium, Spain and Switzerland).
Based on catalogs I own, tires in the imperial designation equivalent to 700C go back at least as far as the 1940s. While it would not be unreasonable to think that the French were manufacturing tires with 700C designations at the same time, I don’t have any objective evidence. I’ve seen French catalogs from the 1950s referencing 700C, though it is unclear if these are tubular or not. Tires with 700C designations were definitely being marketed in the USA during the 1960s, though primarily as specialty items.
With the 1970’s boom, the USA finally became a major market for European, derailleur equipped bicycles. The common tire size was 27” x 1-1/4” but there were also substantial sales in tubular tired models. Many tubulars were actually labeled 27” x 1”. This appears to have been purely marketing, so as to not alienate a potential buyer who was not familiar with metric. While it might seem logical to apply a 28” designation, based on the rim diameter, it was too difficult to explain why a tubular with a 28” designation had a outer diameter smaller than a 27” tire. Visually, 27" was the imperial size, that a tubular was cloest to.
Due the fragility of tubulars, many owners replaced them with clinchers or purchased a set of clinchers for training. The most popular option was 28” x 1-5/8” x 1-1/4”, generally of Italian manufacture. Typically these were more widely available, partially because of their imperial designation and partially because the Italian brands typically had slightly higher pressure ratings. As the boom progressed and consumers became more knowledgeable, tire manufacturers started marking these tires with both metric and imperial designations.
The 28” x 1-5/8” x 1-1/4” tire was not without drawbacks. Even though you did not have to reset pad height, the rim was wider than tubular rims, meaning you did have to reset brake clearance. Additionally, this tire was non-round, having a higher profile. Aspects added to weight and caused clearance issues on some racing models with tight frame design. This opened up the door for the 700C breakthrough, in the form on Michelin’s Elan tire. Introduced in 1976, it was lighter, provided more clearance and a had a slightly higher pressure rating than the existing, competition. As a bonus, it was designed in conjunction with Mavic’s new, narrow, box section rim that was stronger and lighter than existing clincher technology.
The 700C version of the Elan (it was also available in 27” x 1”) quickly became the popular choice of performance orientated cyclists desiring more reliability than tubulars and manufacturers started specifying them as OEM equipment on bicycles. Several major bicycle brands were employing 700C by the end of the decade and by the mid-1980s, 700C was the dominant tire on mid-range, performance oriented bicycles.
700C is simply a metric designation for a tire with a nominal outer diameter of 700mm and a bead seat diameter of 622mm. Equivalent, compatible tires exist in imperial sizes. These imperial tires all have a nominal outside diameter of 28”, though there are variations of bead seat diameters among 28” tires, so not all 28” tires are 700C compatible. Basically, the same size tire exists in both metric and imperial measurements.
The French and English were the original leaders in the bicycle industry and developed separate standards around metric and imperial measurement, respectively. A 622mm bead seat diameter is equivalent to 24.49". This is so close to 24.5", that I suspect the English 28" tire, with a 25.5 bead seat diameter, is the actual origin for the size. If the French had originated the size, I would think that a more convenient bead seat, such as 620mm or 625mm, would have been selected. Most likely, the French simply re-engineered the imperial tire to a metric measurement, so it could be understood in France and other nations where the population and bicycle industry employed metric standards (i.e. Belgium, Spain and Switzerland).
Based on catalogs I own, tires in the imperial designation equivalent to 700C go back at least as far as the 1940s. While it would not be unreasonable to think that the French were manufacturing tires with 700C designations at the same time, I don’t have any objective evidence. I’ve seen French catalogs from the 1950s referencing 700C, though it is unclear if these are tubular or not. Tires with 700C designations were definitely being marketed in the USA during the 1960s, though primarily as specialty items.
With the 1970’s boom, the USA finally became a major market for European, derailleur equipped bicycles. The common tire size was 27” x 1-1/4” but there were also substantial sales in tubular tired models. Many tubulars were actually labeled 27” x 1”. This appears to have been purely marketing, so as to not alienate a potential buyer who was not familiar with metric. While it might seem logical to apply a 28” designation, based on the rim diameter, it was too difficult to explain why a tubular with a 28” designation had a outer diameter smaller than a 27” tire. Visually, 27" was the imperial size, that a tubular was cloest to.
Due the fragility of tubulars, many owners replaced them with clinchers or purchased a set of clinchers for training. The most popular option was 28” x 1-5/8” x 1-1/4”, generally of Italian manufacture. Typically these were more widely available, partially because of their imperial designation and partially because the Italian brands typically had slightly higher pressure ratings. As the boom progressed and consumers became more knowledgeable, tire manufacturers started marking these tires with both metric and imperial designations.
The 28” x 1-5/8” x 1-1/4” tire was not without drawbacks. Even though you did not have to reset pad height, the rim was wider than tubular rims, meaning you did have to reset brake clearance. Additionally, this tire was non-round, having a higher profile. Aspects added to weight and caused clearance issues on some racing models with tight frame design. This opened up the door for the 700C breakthrough, in the form on Michelin’s Elan tire. Introduced in 1976, it was lighter, provided more clearance and a had a slightly higher pressure rating than the existing, competition. As a bonus, it was designed in conjunction with Mavic’s new, narrow, box section rim that was stronger and lighter than existing clincher technology.
The 700C version of the Elan (it was also available in 27” x 1”) quickly became the popular choice of performance orientated cyclists desiring more reliability than tubulars and manufacturers started specifying them as OEM equipment on bicycles. Several major bicycle brands were employing 700C by the end of the decade and by the mid-1980s, 700C was the dominant tire on mid-range, performance oriented bicycles.
