Sub Bass can be challenging because they are so low and it tough to hear on small speakers. Depending on the character of the sound, the sub bass can have frequencies in that range. However, if you want it to stand out you'll need to add some harmonics plugins to bring the out like distortion or saturation, which the FUNK JUNKIE explained as well. So if you're looking for sub bass with more frequencies presence in the 100hz-250hz range do that. Or another cool technique would be to put another bass on top of the sub. The sub will act as the deep end of the bass so the overall low end will sounds nice if you mix them on top of each other correctly. You could also double a sub bass put distortion on one of them and blend them that way too. It's really a matter of what preference and what kind of sound you're going for.