Crank arm coming loose

[marting]

I replaced the chainset on my Single speed (Genesis Flyer) a few months ago (I'm now running a Miche Primato Advanced chainset).

Twice now the non-drive crank arm has come loose mid ride. Is there solution to this other than doing the bolt up RFT? The crank arm states to torque the bolt to 35nm, I'm dubious about going RFT as the old crank-arm was well and truly stuck (My crank arm extractor broke removing it).

Has my new crank arm killed itself when it first came loose, deforming the ally and now it'll never fit?

[marting]

Fluffsri said:

Is this on a square taper? I had the same problem on my SS. In the end i ignored the torque value, applied lots of thread lock and grollied it in. Probably ridden a couple of hundred miles now and still tight, it was coming loose around 6/7 miles of riding.

Yep its a square taper. My SS only sees short journeys (my commute at ~5 mi/day), I reckon its come loose within 30 mi of last torquing it.

Its reassuring to know you've had the same issue and sorted it! I'll get some thread lock and swing on the wrench tonight

[marting]

walm said:

I dunno - the UN55 and UN26 are £10-15 usually, while the hollowtechs, octalinks and powersplines are all in the £10-20 range too.
Not sure there's a huge price difference.
Campag square taper is £50!

Or Phil Wood square tapers at £75!