Originally Posted by
FBinNY
I hear this logic and can't understand the thinking involved. At the height where chain/spoke interaction is important, namely close to the flange, the spokes that are elbow out are the ones that matter. If these are leading, they act like turbine places coming over the top of the chain and forcing it inward until it is forced past the elbow and trapped.
Hmmm... I think you're assuming that the rider would immediately stop pedaling if the chain derails.
If you continue to apply pressure to the pedals (why else would you be downshifting?), elbow-out leading spokes (pointed forward tangent to the hub) will force the chain outward, that is, away from the flange. If the
pulling spokes have their elbows out, the chain will be forced inward, towards the flange, potentially jamming between the sprocket and the spoke.