[jochribs]

Proper torque is in the range of 350 in/lbs by the way. I've never used a torque wrench on a set of pedals in my life and time as a shop mechanic, but pedals require a good amount of force to be sufficiently tight.

 

[jochribs]

I have literally never had pedals come loose. Ever. They literally come out with a snap. I'm not sure many here are tightening their pedals enough.

 

[jochribs]

OP, if you need loctite to hold pedals in to NEW cranks that were stripped due to poor pedal installation, or have a shop drill out your crank arm and install a helicoil to hold pedals into NEW cranks due to a shops poor pedal installation, it is time for new cranks.

Those fixes are bodges that the mechanic/shop/manager can do with them on their own kids bike if they so choose to after the fact. It's not your problem. If the cranks don't hold pedals properly anymore, it's time for new cranks. And not on your dime.

 

[jochribs]

Generally the threads get so buggered from the loose spindle getting to wobble in the cranks threads that the ability to torque them properly after that, and have them hold is compromised.

One thing to look at is the pedals themselves. Are the bearings allowing the pedals to rotate normally? Have they seized at all? If the pedals seize, the pedaling motion will unthread the pedal spindle from the crank arm. Quickly.

Looking back at your post, I'm doubting the pedals seized, and am wondering if the pedals just weren't torqued properly. The motion of repeated pedaling (let alone jumping) will begin to loosen a pedal that hasn't been properly tightened. If it's not caught quickly, it will wreck the cranks.

****Edit: Missed a few things from your post.

-Tapping and cleaning up the threads on a crank that a pedal stripped out of is not something I would have any faith in. Might work for a while, but the threads have been compromised, and the tapping only cleaned up what was left so to speak.

-Loctite is not necessary for pedals installation crank arms. Just some grease and proper torque.

I'm still leaning towards the pedals not being installed/torqued correctly.

 

[jochribs]

You should not have to torque the crap out of pedals for them to stay put. any normal hex wrench is plenty long enough to give you all the leverage you need.

Torquing "the crap out of" is not the same as torquing properly. They still need to be tightened sufficiently.

The reason for them being threaded in oposite directions on each side is to that the pedals self tighten if there is any movement.


The reason for the massive pedal wrenches is to get them OFF

What you're referring to here is 'precession' where the bearings rotation lends to a tightening influence during pedaling, save for the situation where your bearings seize...then they're coming out as if a pedal wrench was on them. However, precession is not a cure for under-tightening. Hence the situations shared above, and fubared crank arms.

Put them in tight enough and they don't loosen. At all.

I would argue as well that the reason for pedal wrenches size is not to just get them "OFF" (as you say), but to also aid in applying the leverage to put them in easily.

Could a hamfisted moron mechanic do damage with one? 'Spose it could happen. Haven't seen it yet, but I have seen morons strip their cranks with loose pedals they didn't install correctly 😁. A good mechanic knows how tight is right.

 

[jochribs]

Thanks. They seem to hold fine (rode rest of day after it was cranked down) and there doesn’t seem to be any wobble at all. Just wasn’t sure if it was worth it to put some loctite to lower the risk of it unthreading again in case the issue just isnt that it wasnt tightened properly by the shop. I def wouldn’t be looking for the loctite to hold the pedals in because the threads got stripped and it wouldn’t hold otherwise.

Totally hear you. Just don't want you feeling like a repair of these cranks if they're damaged enough to require either suggested approach is on you to take care of in this case.

 

[jochribs]

Thanks, very helpful. The pedals (the second time around on the new cranks) was put on by the shop but I wouldn’t be surprised if I didn’t tighten it enough the first time around. I know when I brought it to the shop at the bike park after the pedal fell off over the weekend they noticed the other pedal was a little loose (like 1/2 a turn) and they really cranked both of them tight for me.

No problem. This is what I've been somewhat suspecting...installer error. The concern you have now is if the new cranks were damaged from the pedals not being tightened enough and ridden. Keep a close eye on them. If they start feeling loose or wobbling at all, it's new crank time, again. And in that case, have the shop foot the bill, come on here and we'll walk you through removal and install. Easy stuff, and a good project to get your feet wet on bike repair/maintenance.

Is it different shops doing the install and the subsequent tightening?

 

[jochribs]

Hmm that’s interesting thought on the bearings being seized. Now you mention it, they def do not spin freely like my one up aluminum pedals, though I don’t recall them ever spinning freely even new. I just tried it out and even with some force, the pedals only do 1 full rotation when I try and spin them. I vaguely recall noticing them when I got them and figured that’s just how the pedals were / less chance of slipping or pedal strikes since they were meant for kids?

I clicked on the link for the pedals and I feel it's a pretty low probability that the bearing seized on those pedals. You are probably feeing a good amount of seal drag from the bearings and any seal that's on the spindle to cage interface.

Since they don't have flats for a pedal wrench on the spindle, they have to be broached for either a 6 or 8mm allen. You need to put a good amount of force on the allen wrench (especially if it's a 6mm) to tighten them in properly/enough. The 6mm will bend in your hand a bit, for reference. 8mm is a bit stiffer and not as much. But don't be afraid to put some weight into them.