Broken Pedal

Just a little warning “before” catastrophic failure.
I should have checked, but was always too eager to ride.
Warning signs:

a.) Felt like my right foot or shoe was “leaning” a bit.

I wear the same New Balance 481v3’s when unicycling and I thought the shoes were just falling apart. Like the fabric and the outsole were separating on the outer heel. I remember feeling this at least 3-4 times before the pedal broke off.

I was just about to ride on a steep offroad downhill. So, I was standing up on my pedal and kaboom…it slipped out. I also saw the ball elements from the bearing shoot out.

Not complaining about this brand, they’ve served me well for a few years with abuse. However, I should have paid attention to the weird feeling on one side, and then checked the pedal for play. I’m sure I would have caught it earlier.


Looks, like the axle snapped right off. Hopefully you weren’t injured.

Interesting place for it to fail, would have expected it to break closer to the crank (that’s where my pedals and some other ones I’ve seen broke).

I’ve seen quite a few snapped pedal spindles recently, I wonder if that is because pedal bodies have gotten so durable that they are not thrown out earlier, or because manufacturers have been pushing for flatter pedals (probably both). Or it could just be coincidence…
After my broken pedal mishap, I’ll certainly start to replace spindles after a few years…

Looks like it broke at the skinniest part, which seems to make sense in terms of stresses.


And the most outside part, where you find the lowest bending moment. Hard to say without doing the math where the highest stress is, but I wouldn’t have expected it in that spot.

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If the pedal was slightly loose previously and got ridden a few times, then perhaps it sort of hammered on the end until it pulled off. I’ve seen this happen with a stripped nut before but not with the pin actually breaking, gives me motivation to tighten my pedal because it’s slightly loose.

Yes I have had similar failures. But 3 rides after a twisting full summersalt jammed end of pedal on large rock UPD. It actually as Slamdance described felt “bent” because of the wobble it started. Then out of nowhere it let go at the farthest point from the trailhead three rides after. I pegged it home, broken at the smallest point.

That’s a good point Johnfoss.
The skinny part of the shaft is where it broke.
That also means that the bearing bore at the far end is a smaller and thus a smaller bearing size.
So, a larger bearing on one end, and a smaller(cheaper) bearing on the other. Hmmm…

I’m going to take this to work and try to disassemble in the shop area.
Standbye for more carnage.

It looks to have broken at the end of the threaded part, presumably because of a stress concentration on a crack at the root of the thread. Perhaps there was a bit of movement on it that caused it to cyclically stress it on every revolution.

Assuming that is how it failed, if you look at the broken end you might see where the crack started and how it grew.

Just to keep the thread going, here is a pic of my broken pedal.

I am still baffled why it cracked though where it did - both sides. There is rubber on the edges so no impact damage could have caused it. The bearings were running well.

I was training for a hill climbing attempt at the time.
3 weeks of hill climbing - Cycling every second day
Week 1 - 3027m elevation gain / ave grade 4.71%
Week 2 - 4086m elevation gain/ ave grade 6.49%
Week 3 - 1907m elevation gain / ave grade 7.90%

For the major event - Ski field access road in Queenstown , NZ (960m elevation climb / ave grade 9.6%), I was confident the plastic Welgo pedals standard on the KH29 wouldn’t crack and they survived.

The rubber should help lessen the damage by pedals hitting the ground, but it doesn’t completely remove the forces… The pedal seems comparitively thin in that area too.