Pedal arm falls off

[Davey Do]

I have a wide crank assembly on a four stroke 49cc motorized single speed and have had the pedal arm fall off. Thinking that I didn't have it on tight enough, I put Locktite on the treads and tightened the nut down with a big ole breaker bar. Believing the problem was solved, I rode the motorbike several miles, over a few rides, when the pedal arm again fell off.

Also worth noting is the fact that I've ridden the motorbike without the engine running for a mile here and there. Since the wide crank setup puts a different stress on my knees and other structures, I wanted my body to get use to the wide crank setup, should I ever have a need to pedal it home if unable to do a road fix.

Plus, the pedal arm has always fallen off when I pedal assist up a hill. I live in a rural valley, and there's a relatively steep 1/2 mile grade that's my main thoroughfare. In fact, there's quite a few hills around here. In a 6 mile trek that I call Around the Block, there's four relatively steep hills.

I did a Search on this site and could find nothing directly related. I've gone as far as to consider spot-welding the crank to the pedal arm. If need be, I could always grind off the weld in order to remove the pedal arm/crank. BikeDingleBerry mistakenly sent me another unrequested wide crank, so that too is covered.

Any knowledge or ideas you could throw my way?

 

[Sidewinder Jerry]

Is the pedals falling off or is the crank arm falling off?

 

[Davey Do]

Is the pedals falling off or is the crank arm falling off?

pedal arm

 

[Sidewinder Jerry]

Are they square tapper

 

[Davey Do]

Are they square tapper

L7. Yes.

 

[Sidewinder Jerry]

Are the crank arms old or new? Also do you pull them with a crank puller?

 

[Davey Do]

Are the crank arms old or new? Also do you pull them with a crank puller?

The crank arms came with the kit from BikeDingleBerry.

No need to use a puller, as it easily comes off of the crank. In fact, I used a mallet to hit the arm to assure seating before applying Loctite and tightening down with the breaker bar.

 

[Sidewinder Jerry]

If a tapered crank arm has been properly tighten down on a BB axle it'll be impossible to simply pull them off by hand.

 

[Davey Do]

Do I understand you to say Jerry, that the arm is not properly seated on the crank, and that may be the reason the arm's coming loose?

 

[Sidewinder Jerry]

Very much so. If you remove the axle bolt or nut which ever it might be the crank arm shouldn't come off unless you beat it off or use the proper tool a puller. That's why it's tapered.