Get-me-home advice - stripped crank

[Borderer]

In the summer we attempted to cycle from home to Glasgow to begin An Turas Mor, but had a mechanical on the way when my pedal stripped the crank. I tried threading the pedal through from the other side to rebore the thread, but that did nothing. I then tried a shim in the form of a piece of an irn bru can that happened to be lying on the road - this made it considerably worse if anything. At this point a rescuer arrived and transported us to a bike shop, but I wonder if there was anything else I could have tried. What would you have done if it had happened to you in the arse-end of naewhere?

Does wrapping cotton thread around the screw thread work? I was thinking that maybe I should start carrying a bolt or something that I could replace the pedal with - just to give my foot something to push against to get to where I needed to be, but I don't know if there would be enough clearance for the bolt head/nut in that case.

[Bearbonesnorm]

If the thread has pulled out from the crank arm then there's very little you can do really. You might be lucky (not in your case though Bridget) and find that a shim will provide enough purchase but it's doubtful given the force and load applied through a pedal. As you say - a long nut and bolt would be one solution but in reality, I'd probably just chalk it up as one of those things that's unlikely to happen again (as long as you check that your pedals are tight from time to time).

[benp1]

I would have thought that adding anything to make the male end of the pedal bigger would not work when putting it in the crank, it just wouldn't fit

Solid bit of branch maybe? Just to let you put your foot on it

[Bearbonesnorm]

I would have thought that adding anything to make the male end of the pedal bigger would not work when putting it in the crank, it just wouldn't fit

But if the thread's gone, the hole's bigger Ben.

[sean_iow]

Pedals are cleverly threaded so they undo as you pedal, so seized bearings in a pedal will unscrew it from the crank rather than tighten it up so you can't get it off. This does mean that if the bearings in the pedal aren't free it will start to unscrew.

As Stu has said, check the pedals are tight from time to time, and also make sure they spin freely.

I think that if I fitted a bolt into my cranks that was large enough not to just go through hole the head would stick out enough on the rear to catch the frame.

A crank striping is one of those once in a lifetime bits of bad luck so you'll be fine from now on

[Borderer]

It's actually the second time it has happened to the same side on the same bike. I think it is because that's the side that always gets put down on the ground to protect the derailleur on the other side. The first time I wobbled to a nearby bike shop and they had a crank in stock and fixed it in minutes - the second time it was a bit of a nightmare to source a new crank as the cycling craze in lockdown had emptied the shops of parts.

ETA - the incidents were just over a year apart.

[Bearbonesnorm]

TWICE WOMAN! What are you doing?

[Jurassic]

The same thing happened to my buddy Rambo in the middle of nowhere when we were on a bikepacking trip. We tried a few things to bodge the pedal enough for him to continue the ride but with no success. The final attempt was to use some big cable ties to hold the pedal in (one round the spindle and several more looped through that and round the crank to try to hold it together). He turned back while I continued on to complete our loop, pick up my van and then drive back to collect him. By the time I found him the crank was reamed out so badly that the pedal wouldn't stay put at all and he was walking.

[Cheeky Monkey]

Twice is impressive

Ally crank and steel axles (the former being "soft", the latter being "hard") is, IMO, a recipe for trouble unless you're carefully to align and keep clean when assembling or taking apart.

I've had one crank strip on a ride. Was the weirdest of feelings until I sussed what was going on. I stripped a second being a lazy, ham-fisted spanner monkey. I hope never to achieve a third

[benp1]

I would have thought that adding anything to make the male end of the pedal bigger would not work when putting it in the crank, it just wouldn't fit

But if the thread's gone, the hole's bigger Ben.

Ah, of course, I was thinking cross threaded!

[fatbikephil]

Its only happened to me when the pedal started unscrewing and then the thread stripped when the pedal was only a few turns out. There was just enough thread left to screw the pedal into and and I glued it with superglue bought from a nearby shop. It got me home and I helicoiled it. If the thread is totally gubbed there is nowt you can do in the field. A long bolt and nut may be a bodge to pedal you to the nearest bike shop (or home!) but the bolt head may foul the chainstay. Crank the pedals up to 30Nm and even if greased they shouldn't come undone.

[pistonbroke]

It's more common than you'd think. I used to maintain bikes for a young rider who was on the British Cycling World Class Performance Programme, the constant packing and rebuilding her bikes involving removing pedals took it's toll on the threads. I put it down to her always losing the washers, forgetting they were left and right hand thread and attempting to screw in the wrong pedal and not tightening them enough. CroMo or Ti axles and Aluminium castings don't like frequent tightening and loosening, I favour using copper anti seize, if the cranks are expensive, it is possible to helicoil the thread but this isn't a trailside fix.

[ScotRoutes]

Pedals are cleverly threaded so they don't undo as you pedal,

FTFY

[Borderer]

TWICE WOMAN! What are you doing?

well, Joe had been riding my bike so I blame him. The first time he had been coasting along off the bike, but standing on the left pedal as we went through the pedestrian area of a city in the states, Albany I think.

The second time I think was caused by putting a loaded bike down on the grass which made it pivot on the pedal. It might also be that my cheap pedals aren't machined to quite the high standard they could be. I dunno, I'm guessing. We have taken our bikes on a fair few planes so we had to keep removing the pedals, which isn't great for them.

Either way it's pretty much game over. I did manage to sort of push on the end of the crank with my foot to help things along but you would be doing well to travel a mile that way.

Thanks for your replies. Good to know that I didn't miss an easy fix. Cheers.

[Borderer]

Pedals are cleverly threaded so they don't undo as you pedal,

FTFY

FIFY

[sean_iow]

Pedals are cleverly threaded so they don't undo as you pedal,

FTFY

Are you sure, the right hand one has a right hand thread, so pedaling clockwise with the pedal held still it would undo?

That's how I work out how to undo mine, and then confuse myself as they use hex keys on the inside which reverses the direction to turn

[ScotRoutes]

Precession tightens the pedal.

[Lazarus]

when it happened to me nothing fixed it and i cycled hiome on one leg thankfully only 10 miles and flat

Worst bit was i was just going up a steep hill so put the power down and immediately hit the floor and i crashed. This confused me and when I stood up only then did i realise my pedal was still clipped to my shoe and understand why I crashed.

Thats once in god knows how many thousands of miles.

[sean_iow]

Precession tightens the pedal.

That only works if the bearings aren't seized/stiff so the greatest force is the friction of the bearings on the spindle and there is clearance still between the bearings and cage to allow the action of the torque to rotate the opposite direction. If the bearings are tight that force is greater and the pedal unscrews?

[In Reverse]

It's happened to me twice too. Both times with SRAM cranks.

First time was at the top of Jacob's Ladder, which made the ride back down interesting...

[Moder-dye]

Happened to me, drive side on sram cranks. Luckily, though I was on holiday, I was not in the middle of a bike packing trip.

It seemed impossible for the local bike shops to order (through their stockists)and fit them for me, so good old wiggle was engaged after some faff with the LBS saying they get them (and then not) and a new crankset arrived the next day!

I think mine might have been because I often remove that pedal when I have the bike stacked on the back of the car with family bikes too. Possibily hadn't been tightening it up enough as I new I'd be having to take it off again each time we moved so it had ground itself out. I'm bigger than your average bear so probably helped the grinding out.

[Borderer]

Pedalling tightens it up. That's why it is designed like that with a reverse thread on the left - otherwise you would undo it as you rode.

[psling]

Pedalling tightens it up. That's why it is designed like that with a reverse thread on the left - otherwise you would undo it as you rode.

Except when, as others have posted above ^^ the pedal axle itself is seized or sticking in which case the effect is reversed. Workshop tip - You can wind pedals into the cranks quickly by holding/locking the pedal axle and reverse-pedalling the cranks; if you do the same pedalling the cranks forwards they will undo

[fatbikephil]

Errrrrr......
LH thread on left hand crank - pedaling anti clockwise as you look side on = loosens thread as you pedal
RH thread on right hand crank - pedaling clockwise as you look side on = loosens thread as you pedal

Put a spanner on the flats in line with the pedal and stand on it - the pedal thread will loosen. It's a typical stupid bit of bicycle design to stop them getting tightened up (by pedaling that is) to the point that you can't get them undone. In reality (and now that most pedals have a nice 8mm AF socket bolt in them.) it should be the other way round to stop them coming undone mid ride.....

[psling]

This is one of those things that's hard to get your head around! (well, for me, anyway!).
htrider and myself have said exactly the same thing using different words (as Sean & Colin did earlier). I think the critical point is to remember that the pedal platform rotates around an axle which is itself fixed directly to the crank. So, if the pedal platform is rotating around its axle freely it won't undo from the crank whereas if the axle is seized and the pedal platform does not rotate freely around it (the axle) then the axle can unscrew/loosen from the crank whilst pedalling forwards. When you fit or remove pedals you are turning the axle, not the pedal platform. When you are riding, you are turning the pedal platform and (hopefully) not the axle. The waters are muddied a bit by what I think Colin referred to earlier (precession) when a freely rotating pedal will tend to tighten to the crank slightly with forward pedalling.
It is a (very) long time since I last studied physics so the above may of course all be a load of spherical objects