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Pedals are obviously a critical interface with the bike. A broken pedal axle would be catastrophic, most likely causing injury or even death, especially considering that pedal failure would really only occur during massive impacts. In light of this, is there a standard for how strong pedals and pedal axles have to be? Are road/XC pedals necessarily weaker than their burlier MTB counterparts? I've never seen a pedal marketed with a maximum load rating or anything. Pedal breakage, although rare, does occasionally occur for reasons other than manufacturing defects, so it is a valid concern.

Hypothetically (or in real life!), would I be able to safely ride a road pedal down Red Bull Rampage or some other similar event with gigantic drops and jumps?

What about other components of the pedal interface? The threads? The threaded insert in a carbon crank? How about the cranks themselves?

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    Some pedals do have load ratings, though it is uncommon. The Speedplay Nano, for example.
    – Adam Rice
    May 1, 2021 at 20:10
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    Most pedals with titanium axles had an 80kg rider weight limits. For some reason they've been removed from their catalogue. Speedplay Ti are only available with the short spindle, steel versions may have short, medium or long spindles.
    – Carel
    May 2, 2021 at 14:18

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What about other components of the pedal interface? The threads? The threaded insert in a carbon crank? How about the cranks themselves?

I'll use the "pardo" durability index to answer. The durability index is based on the number of failures at http://pardo.net/bike/pic/index.html.

For pedals, we see three failure events.

For cranks, we see 55 failure events.

So it seems based on this that the crank pedal eye fails far easier than the pedal connected to it.

One reason is that the pedal to crank attachment has a design flaw, and the crank, being made of aluminum, is the component that suffers as opposed to the pedal spindle made from steel, a far stronger material. The design flaw can be seen from the left pedal having a left hand thread -- a proper design would not be sensitive to threading direction. It can also be seen from old cranks, from which the removal of pedals sometimes is a Herculean effort and even when it isn't, the pedal eye of the crank is visibly worn. The pedal to crank pedal eye attachment should have a 45 degree taper, similar to automotive lug nuts.

Of course, non-catastrophic failures of cheap plastic pedals happen often. Those are used only in inexpensive bicycles intended for little kilometers in their lifetime, for light riding.

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  • Those numbers nicely underline my own experience: I believe I've only broken one cheap set of pedals (nonproblematic failure), but I have definitely broken a steel(!) crank and several BB axles (all but one catastrophic failures). I don't ride aluminum cranks because I don't trust them, so I do not have the pedal eye problem: The screw-in design for pedals has been developed in a time when all cranks were steel, and steel is perfectly able to withstand the stresses on the thread virtually indefinitely.
    – cmaster - reinstate monica
    May 1, 2021 at 9:26
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    "The design flaw can be seen from the left pedal having a left hand thread -" NO! Just to remind you that sports cars with a single central wing-nut for the wheels also have/had (the type is rare these days, except for F1)) right or left threaded nuts depending on the side, for exactly the same reason as pedals.
    – Carel
    May 1, 2021 at 11:51
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    @Carel Jobst Brandt would have disagreed (sheldonbrown.com/brandt/left.html): Left-hand threads would not be required on left pedals if a design common on cars were used. Before the advent of conical lug nuts, many cars used left-hand threads on left-side wheels. Today, stories of wheels rolling away from cars no longer make news, the conical seat having solved this problem on car wheels as it could on bicycle pedals.
    – juhist
    May 1, 2021 at 12:29
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    @juhist I'm not sure the car analogy is valid. Car lug nuts (multiple lugs) don't need to withstand bending forces (only axial forces plus tangential-radial ones). Pedal joints do, so even with the 45° taper you can't completely avoid the precession movement unless you tweak the design even more (multiple bolts, or another tapered section on the other side of the crank).
    – leftaroundabout
    May 1, 2021 at 18:04
  • @juhist : Introducing a taper would also mean the loss of downward compatibility and the need for two production lines for pedals & cranks because there still millions of bicycles around with left and right threads. The cycle industry would be very happy to retool. (Speaking of cars again, I also remember that my old Alfa Romeo 75 had tapered wheel-nuts, 5 per wheel, with left & right hand threads! The tapering ensures that the wheel is correctly centred on the axle.)
    – Carel
    May 2, 2021 at 13:58
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The part that fails seems to be the thread in the crank arm, and that mostly due to poor installation with cross threading and/or riding it loose, if we go by the number of questions about pedals asked on the site.

Bearings will wear out over time naturally, due to usage. This gets accelerated by riding in the rain, dirt, and storing the bike outside.

In all my life I have bent one pedal axle, and while it was perceivable, it did not stop me riding that bike for years more as a teenager. I have also lost a Look pedal body once, when the retainer ring unthreaded and the whole platform fell off the pedal axle while I was walking the bike.

I would estimate that outside of collision damage, any pedal will last for many years until gradual wear claims it, in bearings or clip interface or similar.

I'd suspect that the subgenre of cyclist who is most likely to bend a pedal axle would be a BMX rider who is doing stunts and tricks.

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  • That said, I've never used specifically lightweight pedals, that part of the question will need an answer from someone who has experience of them.
    – Criggie ♦
    May 1, 2021 at 2:38
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    There are also titanium-spindled pedals to consider, of which I have several, and which must be weaker than steel ones.
    – BetterSense
    May 1, 2021 at 2:50
  • @BetterSense they exist, and Titanium is used for lightness. However can't show if they're weaker because of that. mbr.co.uk/news/this-titanium-pedal-is-only-50g-405745 for example are 50g each.
    – Criggie ♦
    May 1, 2021 at 7:36
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    That Element22 looks like they saved weight by moving most of complex parts to cleat
    – ojs
    May 1, 2021 at 12:23
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    @ojs: Agreed, similar to Speedplay. Their pedals are mostly just an axle, bearings and a small body for the cleats to latch onto. The springs and clamping mechanism are in the cleats. The main advantage is that you can clip in from both sides without duplicating the springs.
    – Michael
    May 3, 2021 at 9:21

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