Hi, my bike is kind of broken When i use it the pedal falls

File: 20151008_103724.jpg (3MB, 4128x2322px) Image search: [Google]

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Here's a pic of the nut

File: Nylon_Insert_Locknut.jpg (13KB, 291x300px) Image search: [Google]

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Take the nut up to your local hardware store and grab a matching size locknut
They have a little insert that grips on the shaft to prevent it from backing off

>>885590
Are the threads undamaged on the nut and the bolt? If they're not, replace or repair the threads.

Alternatively, get a lock nut, or pour locktite all over your nut. Not sure how long that last solution will last.

>>885590
>soldering it directly
weld it my son

>>885590
Do you live near yuppie bike shops?

>>885602
This, basically. Check threads on craftshaft. If OK, replace nut with new from bike shop and use blue locktite to hold.

>>885596
Normally I'd agree but OP really needs a flange nut in this application. He won't have enough threads for nylock to engage, with or without a washer.

Your problem is not the bolt or the bottom bracket. Check the inside of your pedal arm. Its bent out. So it doesnt matter how hard you tighten that bolt. Its gonna wobble itself loose. New pedal arm will solve your shit, son!

Are you trying to tighten the crank arm on with the nut, don't do it.
Tap the crank arm on with a soft mallet, then use some thread lock solution and snug the nut up to hold the crank arm on.

>>885663
This anon is right, replace the pedal arm and be done with it. Thread lock glue on screw will prevent this from happening sooner.

OP doesnt need loctite for this to work. Just replace the pedalarm and remember that sides pedalthreads is opposite. Lefty tighty righty loosy.

Working in a bikeshop for the last 5 years. I havent had the need for loctite yet. And id prefer people dont use it before they bring it to me all f'd up. Just tighten it down good. Itl be fine

>>885590
That happened to me years ago. I didn't own a socket wrench set at the time and could never properly tighten it enough. It always loosened up during normal use. Once I did get a socket set, I made sure to properly tap on that pedal arm as far in as it would go. Next, I tightened that damn nut on once and for all. Never came off again.

>>885590
As other anons have said, locknut and the proper socket to tighten it. A quick and dirty method uses a dab of fingernail polish on the threads. That will keep it from backing out and still be removable. Blue threadlock also works but that costs more than nail polish.

>>885740

This is likely the case, how are you tightening it?

ideally you would use a 6 point socket of at least 3/8 drive

>>885663
this guy^^^ is the most-correct answer so far.

when a bicycle crank nut comes loose, the spindle chews up the hole in the end of the crank, and then the crank won't sit properly on the spindle anymore. It is most likely to just keep coming loose.

You probably need a new crank, and (possibly) a new spindle (the center axle that the cranks turn on). You would have to see if that is damaged or not.

>>885590

In addition to what others have said, make sure that this nut isn't reverse-threaded. One side of those cranks is always reversed so it doesn't come off when you pedal.