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What is the typical and generally accepted minimum clearance between the ground and pedal? Does this vary between different bike styles (road, gravel, mountain)?

I've read that designs with low clearance are generally more stable, due to lower center of gravity, but I could not find a number for what "low" actually is.

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    A lot depends on the surface. Roads tend to be flat and predictable, whereas off-road has more variability needing more space.
    – Criggie ♦
    Commented Oct 9, 2023 at 0:55
  • Does a low center of gravity really help for balancing on a bicycle? It probably helps if the bike’s CoG is low relative to the rider, but apart from that I doubt it makes a difference. It’s not a 4-wheeled vehicle where you risk tipping over.
    – Michael
    Commented Oct 9, 2023 at 6:53

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Clearance is a function of the bike's geometry, crank length, bottom-bracket width, tire width, and pedal design. So it's difficult to talk about a single number that takes all these variables into account.

The number that we look at in the frame's geometry is "bottom-bracket drop," which is how far the centerline of the BB is below the centerline of the hubs. This is usually about 70 mm for road bikes. I've never seen it as high as 80 mm.

There are other factors that play into stability too: head angle, trail, wheelbase, probably some others.

[added later]

The other consideration is the type of riding you're doing. Clearance determines whether you can pedal through a turn when leaning over without striking your inside pedal. If you're on a touring bike, maybe you don't need to pedal through turns at all. On a track bike, you absolutely do need to pedal through turns, and you're on a banked track to boot. So track bikes need a lot more clearance.

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    Consider suspension (especially full squish) sag has a big impact on BB Drop, therefore BB height and becomes a dynamic measurement.
    – mattnz
    Commented Oct 9, 2023 at 1:30
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    Just out of interest, I randomly checked a few bike measurements on geometrygeeks.bike and largers frames tend to have slightly lower BB drop, for example a 2023 Look Blade RS has 73 mm in its smallest size and 68 in XL. Same to a certain degree for all (road) bikes I've checked. I assume that is mainly done to compensate for the higher center of gravity on large frames?
    – DoNuT
    Commented Oct 9, 2023 at 6:48
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    @DoNuT: Large frames often ship with 175mm crankarms while the smaller ones come with 170mm or less. So it stands to reason that the BB drop would be at least 5mm different for the same ground-pedal clearance.
    – Michael
    Commented Oct 9, 2023 at 6:50
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    @Michael Ah yeah the other way around, actually. Makes sense, indeed and true for Look, for example (XS-S 170 / M-L 172,5 / XL 175 - exactly matching the BB drop of 73/70,5/68)
    – DoNuT
    Commented Oct 9, 2023 at 7:01
  • The banking on a track helps with pedal clearance because the surface under the inside pedal is lower than under the wheels. As for touring bikes, carrying speed through a bend into a climb is quite desirable with a load, and they can often be ridden on rough tracks (even when being used for actual touring, rather than as endurance road bikes). They also make good commuters, when the rider might be in a hurry. My tourer has slightly less BB drop than my gravel bike, at least when the latter is running the same 32mm slicks I use on the tourer
    – Chris H
    Commented Oct 15, 2023 at 11:16

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