Monostable pulled fronts and logarithmic drifts

In this work we investigate the issue of logarithmic drifts in position level sets solutions monostable reaction–diffusion equations, with respect to traveling front minimal speed. On one hand, it is a celebrated result Bramson that such drift occurs when reaction KPP (or sublinear) type. other also known phenomenon disappears speed nonlinearly determined. However, some equations fall neither those cases and our aim fill gap. We prove always linearly determined, but surprisingly find factor term may be different from case.