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Do you know the history of 700c wheels in road bikes?

by Martin Yang 06 Oct 2024
Do you know the history of 700c wheels in road bikes?

Though we take for granted 700c, what does it really mean?

Road bike components feature an almost endless set of "standards," with fresh ones developing practically annually. On almost all road bikes and many hybrid cycles, the 700c wheelset is a long-standing standard used for years, though.

700c denotes what? Why is this crucial? Furthermore, why, in some respects, are alternative wheel sizes threatening its supremacy?

 

What is a 700c wheelset?

The 700c wheelset is the standard configuration for road bikes.

Most road bikes use 700c wheels, although the name doesn’t accurately represent anything specific.

The "700" part refers to the approximate diameter of the tire’s outer edge in millimeters.

A wider or narrower rim will shape the tire in different ways.

 

The breadth of a bicycle tire will determine its real outer diameter in particular. Usually having a greater outer diameter than a 23mm tire, a 28mm tire fitted on a rim with the same internal width can have a somewhat different overall diameter depending on its form.

The internal width of all 700c wheelsets was essentially the same in the past, but today the range of rim widths for road bike wheelsets vary greatly, from less than 15mm to over 25mm, which will affect the ultimate size of the tire's outer diameter.

 

How large is a 700c wheelset?

The diameter of a 700c wheelset is 622mm, as specified by the ISO 5775 standard.

 

Measuring 622mm, a 700c wheel set's diameter is the breadth between tire bead seats.

The ISO 5775 standard specifies this size, which is significant since it implies that any tire meant for a 700c wheelset should match any 700c rim. Still, the tightness of this fit might differ greatly.

 

Why the "c"?

 The bead seat diameter is not as important now.

 

Let's look at the "c," as it's now abundantly evident that the "700" component has little bearing on modern bicycles. Not unexpectedly, this section is out of date and has minimal pragmatic value either.

There used to be additionally 700a, 700b, and 700d wheelsets historically. Depending on their use, riders would alternate between a, b, c, and d wheelsets; 700c and 700d were preserved for racing; the broader 700a and 700b wheelsets were used for early 20th century training on rough, unpaved roads.

The 700a, 700b, and 700d wheelsets had different bead seat diameters than the 700c; hence, you would need different tires to match each type of rim even though they all finally achieved an outside tire diameter of roughly 700mm.

 

The old wheelset standards had different bead seat diameters, which meant that different tire sizes could be mounted on the same frame.

The good news is that you can be quite certain that they all fit your frame.

However, this posed a bit of a challenge for riders and tire manufacturers. As a result, European wheelset and tire manufacturers decided to establish 700c as the optimal wheelset standard for road bikes on the increasingly improving road surfaces at the time, and they stopped producing 700a, 700b, and 700d rims and tires.

 

700c vs. 650b Wheelset Sizes

The 650b wheelset is popular on gravel bikes, and many frames are compatible with this wheelset size.

 

Following the phase-off of 700a, 700b, and 700d, the 700c wheelset practically controlled the drop-bar road bike market. Many hybrid bikes also include this wheel size; some have smaller wheels too.

Originally adopting 700c wheelsets, gravel bikes followed this trend, although these days they usually include 650b wheels. Remember that 650b is equal to 27.5-inch mountain bike wheels; hence, riders may install wider gravel tires while still keeping a comparable total diameter to a 700c wheelset with narrower tires.

This means that although the frame has to be built to provide greater tire clearance, you can retain similar frame geometry and handling. Equivalent gearing from the powertrain is also possible, as wheel size determines the distance covered with each pedal stroke. Lower tire pressure made possible by wider 650b tires lets you ride more comfortably and increases traction since more rubber comes into contact with the road.

 

The 650b wheelset allows for the use of larger tires.

 

Many gravel bike frames let you alternately use 700c and 650b wheelsets.

Small-frame bikes also include the 650b wheelset. Using 700c wheels might complicate road bike design for frames less than 50 cm since they often need a smaller head tube angle to place the front wheel far enough from the bottom bracket to minimize toe overlap.

Smaller bikes thus handle differently than bigger bikes of the same brand.

Some brands, including Canyon, are now providing 650b wheelsets on some of their smaller-sized road and gravel bikes such that the frame geometry stays roughly like that of their larger bikes.

 

Are 700c wheels the same as 29-inch wheels?

29 inches and 700c: different names for the same thing.

 

Mountain bikes started in the United States, so they measure usually in inches from frame sizes to wheel sizes (the same holds true for children's bike wheel sizes).

Mountain bikes were first commonly featured 26-inch wheels.

This has altered over the past ten years; most contemporary mountain bikes include 27.5.5-inch or 29-inch wheels. These two diameters match the 650b and 700c wheel sizes specified in the European ETRTO standard and include the identical bead seat diameter.

This helps to explain why 700c tires should fit 29-inch mountain bikes and vice versa.

 

The cassettes on road bikes and mountain bikes may look similar, but the standard length for road bikes is longer.

 

In fact, mountain bike wheels tend to have wider rims than road bike wheels to support the wider tires used on mountain bikes, so they are not completely interchangeable.

Additionally, it's important to note that the standard Shimano/SRAM freehub and SRAM XD freehub on mountain bike wheels are slightly narrower than those on road bike wheels. As a result, road bike cassettes do not fit mountain bike wheels, and mountain bike cassettes require spacers to fit road bike freehubs.

 

 

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