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I don't understand why virtually all road bike sizes use the same wheel size. To give an example, the Pinarello Dogma F12 comes in 13 different sizes, and, as one may guess, the smallest is significantly smaller than the largest. The crank arm comes in three different lengths (depending on the bike size). However, the wheels are always the same size.

Why is 622 mm (700C) so special?

Wouldn't (some) riders benefit from smaller (or larger) wheels?

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  • 1
    many manufacturers spec smaller frames for 650b or even 26" wheels. Feb 9 at 18:04
  • List of UCI approved wheels for racing assets.ctfassets.net/761l7gh5x5an/5qmS7gxC8fdXjctyqgwNph/…List_of_approved_wheels-_FRA-ENG.pdf
    – Criggie
    Feb 9 at 18:32
  • Along the similar lines, MTB wheel sizes vary (old school 26, 27.5" and 29er) , but while some spec smaller wheels on smaller frames, most use same sized wheel on all frame sizes.
    – mattnz
    Feb 9 at 18:48
  • Follow-up: bicycles.stackexchange.com/questions/82816/…
    – fho
    Feb 10 at 11:51
  • Gravel bikes (that are technically road bikes) are using two wheel sizes: 700C/622 and 650B/584. The goal is to keep the same outer wheel diameter if using different tire width: thin tires with 622 rims and larger tires 584 rims, but it's a workaround given the reference outer diameter is still 700C, so it doesn't add much to the question tough (more recent gravel bikes start to have enough clearance to have 45mm tires with 622 rims though).
    – Renaud
    Feb 10 at 14:04

1 Answer 1

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Smaller wheels, yes. Bigger wheels, not necessarily. This is a matter of being able to build a frame that fits the rider and the wheels; any differences in rollout can be compensated for by changing the gearing.

In the past, 650C was a somewhat-common wheel size for small road bikes, and there was one brand that specialized in bikes for women (Terry) that used a 24" front wheel on smaller frames, but these designs have become very uncommon (I've seen one bike that uses 24" front and rear, which solves the problem of needing to carry two innertube sizes).

I agree it's unfortunate because there are inevitable design compromises trying to fit big wheels on a small bike. Here's an essay by a custom builder on wheel sizes for small bikes. Long story short, there's not enough volume to support frames and tires for 650C wheels in the mass market. More recently, 650B (which is slightly larger, 584 mm vs 571 mm) has emerged as a fairly popular size with a good selection of tires available, although I'm not aware of major bike manufacturers speccing them on smaller frames.

With big bikes, there's obviously no problem fitting a 700C wheel, and there's not really a need to put bigger wheels on bigger bikes beyond aesthetics, perhaps. That said, there are a few companies that specialize in building bikes with 32" and 36" wheels. One of the presenters on GCN is very tall, and they did an episode with him riding a 36er.

In short, there's nothing special about 700C beyond the power of having a standard wheel size. I'm curious myself how the industry landed on that particular size as the standard.

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  • Also: using different wheel sizes for different frame sizes would imply that they'd require stock-keeping of different wheels, tyres, tubes, rims, spokes but more annoyingly different gearings, both for chainrings and cassettes to keep uniform RPM habits, especially on group rides. Also when on a group ride you won't be able to help out a mate with a tube when theirs is shredded but of a different size.
    – Carel
    Feb 9 at 19:48
  • 2
    canyon endurace and rose pro sl both use 650B for smaller sizes now
    – calofr
    Feb 10 at 7:59
  • @calofr good to know!
    – Adam Rice
    Feb 10 at 14:15
  • @Carel inner tubes are cross-compatible between 26" - 29" or 24" - 27.5". It may require a bit of stretching or squeezing, but it'll generally work. Feb 10 at 16:57
  • @leftaroundabout: Those two yes, but I would not try with PU tubes, though.
    – Carel
    Feb 11 at 18:10

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