I think you'd have to be riding very slowly for photochromic lenses to help O.P.

Riding some of the bike paths around Tucson, my Rudy Project photochromics would let me see at the end of the tunnels, but while riding the beginning of an underpass (occasionally with a turn at the bottom!) they were practically opaque. It just took that long for the lenses to lighten. Coming out was marginally better, since the lenses darkened faster, but it still wasn't a good for the first hundred yards or so.

How about the old fashioned way? Squint going into a dark zone and open wide as you hit the shadows. When you hit the sunshine, squint again and gradually open your eyes. It's almost like your body was designed for such shenanigans!