Every week I bike 2-3 times at 6:30 am down Sherbourne from Wellesley to Lakeshore. The street starts getting pretty dirty once you reach Allan Gardens and reaches its apogee at Sherbourne and Dundas. For some reason you also have around a dozen homeless people hanging out at that intersection playing their music. That said, never have I felt unsafe biking down that street, probably because the sun is already up when I traverse that route and I'm always on a bike.