Not sure about a 1090 crusade, but the HRE does join some crusades. Just bear in mind the HRE is in near perpetual succession type wars and rarely has the means to participate in external conflicts. Also, perhaps it has something to do with the HRE being free investiture compared to many other catholic kingdoms that are papal investiture. Perhaps that reduces their chance of involving themselves in crusades. Nonetheless, the HRE does take part in crusades, just not as often as some of the smaller Kingdoms.