Originally Posted by
HillRider
The large chainring is swaged permanently to the crank arm and can't be removed or replaced. The smaller ring can be unbolted and replaced.
Basically, this is a very low-line crank and the nutted bottom bracket further indicates this entire thing was pretty much bottom of the product line. If you want to use this cranks as a single chainring, you've got to use the existing big ring as is.
You could replace it with any JIS square taper crank if (and this is a big if) the current spindle is the correct length. Frankly, I'd get a complete new crank and matching bottom bracket.
I have 2 presently installed BBs like Laundymat has-one working fine and another needing replacement as it no longer holds the crank very long.
But I also have 2 unusally long ones I got because of the spindles-one is a 123 offset with a 128 drive side equivelant, the other a 134 length. Thought these might come in handy when I need extreme chainlines such as a mod I made replacing the 125 mm dropout on a French wheel with a 140 dropout from a tandem or whenever I build something with quadruple or quintuple cranks.
Are these crank retention problems typical of this nut type BB axle? Or is there another reason for the disparagement?