Giant timber bamboos, such as moso (Phyllostachys pubescens) and guadua (Guadua angustifolia) are potentially well-suited to the production of engineered strand-based structural composite building materials. There is no information available for guadua, but moso bamboo is known to produce good-quality, strand-based composites. However, economically viable commercial production of these composites is hindered by the lack of an efficient, automated method for converting culm stock to strands, and very little technical information is available regarding strand production and quality. In this study, moso and guadua culm characteristics and tissue re-saturation behavior likely to affect stranding were measured and compared. Strand size classification and the thickness and width distributions from stranding re-saturated moso and guadua quartered culm pieces using a CAE 6/36 single-blade disk flaker were determined. While node frequency was lower in guadua than in moso, the diaphragms and embedded wall tissue were much thicker and tougher, with strong negative effects on strand quality. When cut to a target thickness of 0.65 mm, moso bamboo produced strand thickness frequency distributions close to those found in sampled mill strands of trembling aspen, while guadua caused high wear on blades and yielded a greater proportion of excessively thick, broken, and very rough strands.