Poses of charging horsemen attacking English (to the left of shieldwall in Tapestry) look as caught just before throw. Maybe It is simply overarm style, but It seems different to that from right side of shieldwall (with no doubt overarm style), seems to be more "sprawling". It may be my oveinterpretationThere is, for example, precisely one Norman horseman throwing his lance on the Bayeux Tapestry. One.
If It is overarm style, horsemen throwing spears are just as numerous in Tapestry as... horse archers
Isn't there really any another evidence regarding Norman cavalry throwing their spears?
As you said, perhaps fence - this is why I think that one or two cavalry units in Frankish roster shouldn't change weapon to swords but use spears in melee.I can safely say he never existed in the Eastern Frankish/German lands. Ottonian and Salian cavalry would use their lances to thrust and, perhaps, in Ottonian time to fence.