The Ashtabula crank is simple, robust, and easily serviced... it is also heavy and limits one to using 1/2 inch pedals which is fine on cruisers but can be a problem on bikes when you want to run clipless or toe straps and cages.
I do have some 1/2 inch road pedals on order...
Converting an English bb to an Ashtabula would be an epic bit of work and cannot see why someone would want to do this.
Now relegated to being used on the least expensive bikes they tend to be of lower quality than those cranks of old with high quality forged arms and good quality bearings.
There was also a conversion kit / adaptor that would allow one to use cottered cranks with an Ashtabula bottom bracket... I have a few of these.
Those old one piece cranks can be very beautiful and very smooth... I won't be converting this one.
