As to weather, I was commenting on the relative number between summer and winter. In both years, they hold up better than I would have thought, at around 50%. That would fit with, for example, commuters using the bike year-round, with the other half in summer consisting of tourism, generally increased activity, joyrides, etc.

As to Giffen: people are shifting public transport -> car & bike. The "budget" (road capacity) is fixed and close to full utilisation. Increased demand with inelastic supply results "inflation", which is the somewhat convoluted way the income effect comes about. Aaaand... yeah, I can't quite remember how I made the next part fit. so you may be right.