Octalink is definately fine for backpedaling. So I wouldn't worry about it.
well the problem i see in octalink is that the grooves of the bb and crank are not conic so if the grooves of the spindele dont match exactly up with the ones of the cranks you can slightly turn the spindle in the crank while packpedaling what results in a loose crank bolt. if the force is all the time in the same direction like on a freewheel it should be fine but not on a fix.
so how does the conection of left crank and bb look like is it conic like a squeretaper or more like the splinted octalink?
Gary Fisher Aquila (retired), Specialized Allez Sport (in parts), Cannondale R500, HP Velotechnic Street Machine, Dented Blue Fixed Gear (retired), Seven Tsunami SSFG, Specialized Stumpjumper Comp Hardtail (alloy version)
I've been riding with this crank on my bike for a year now and right through a Wisconsin winter. I have no complaints about it. Skidding would be no problem if I were geared down and on a bike with a shorter wheelbase.