Crank keeps coming off

[dmgraham8]

Hi CC gurus,

I bought a used Giant Sedona.

Left Crank keeps coming loose and falling off. Can I just replace crank or is the spindle / BB a problem?

Photos attached.

Thank you in advance!
Dave

 

[Paulus]

That crank has had it. It has come loose at some point and has rounded off ever so slightly so that it it will always , no matter how tight you do the bolt up, it will always come loose again.
You can easily get a replacement left crank of the same size, ie. 170/172.5/175, the size should be on the rear of the crank.
You may get an exact model, but something very similar would do.
Your local bike shop could provide one from it's parts bin, or there is always the Bay of E. As long as it is a Square taper crank.

 

[Paulus]

PS, check that the right hand crank bolt is tight, or the same could happen.

 

[Ming the Merciless]

That looks stuffed. Been loose for too long and under pedalling forces. Must have been making a racket and being ignored.

 

[Jameshow]

If desperate get a brick or concrete block and place crank on it bottom bracket on next and damaged crank on top give it a big wack with a club hammer so that the alloy is deformed by the steel bottom bracket and tighten up very tight!

 

[ColinJ]

If desperate get a brick or concrete block and place crank on it bottom bracket on next and damaged crank on top give it a big wack with a club hammer so that the alloy is deformed by the steel bottom bracket and tighten up very tight!

And then don't pedal standing up when this starts to happen...

 

[ghawks100]

No point in doing a bodge job. It will only come off when you least expect it too. It could even injure you when i5 comes off.
It will almost certainly be when you are furthest away from home too.
Replace the worn crank with a new one.

 

[lazybloke]

I remember cycling up Box Hill many times as a teenager and pressing my nose against the glass of a very flash bike shop: Dauphin Sport.

Aged 17 I somehow fitted 3 jobs around my A Level studies, and there came the day when I went in and bought a lovely, shiny, brand-new Campagnolo chainset.

I was gutted when a year or so later, one crank had same problem described by @dmgraham8.

Will never know what I did wrong... probably I mixed up Newton Metres and degrees Farenheight my torque wrench settings.

I still haven't thrown away the chainrings; they're the manifestation of my childhood dreams!

 

[presta]

And then don't pedal standing up when this starts to happen...

View attachment 694825

Or else this will happen.

 

[HMS_Dave]

Looks like neglect on the previous owners part perhaps. Looks like someones had a go with a hammer on it. As suggested a new crank required.

 

[Ajax Bay]

Likely the BB (spindle of steel) is not an issue. The OP can check it's still smooth by feel.
Just get a new LH crank of the same length and install. The inexactness of the colour/make match is up to the OP.
Ride on, on that chain with a great reddy-orange colour (maybe just the light).