The preference for bimoraic stressed syllables in pre-Old High German necessitated the phonological restructuring of syllables with stressed, short vowels either by early implementation of open syllable lengthening (non-shifting dialects north of the Benrath line) or by triggering an autochthonous phonological shift of +t, +p, +k after short vowels (shifting dialects). From there, the OHG dialects “progressed” though the rest of the shift in a largely parallel fashion. Asymmetry of the shift of +-p and +-k and geminate +-pp and +-kk was caused by place bias, however, especially in the Rhenish dialects where tone accents could sometimes delay or block the shift of these segments. The greater susceptibility of the more marked labial and velar affricates (-pf- and −kx-) to weakening limited their later occurrence to dialects outside the Rhineland. The reanalysis of aspirated +t- [th], +p- [ph], +k- [kh] as affricates in initial position was possible only when the corresponding geminate had already shifted, exemplifying both the effects of place bias as well as a kind of phonological reanalysis Blevins (2004) calls “choice.”