Keeping feet warm.
Keeping hands warm while riding was an issue until I discovered Bar Mitts/Pogies.
Keeping myself warm if a mechanical issue would force a stop.
Keeping hands warm if a mechanical issue would need to be fixed mid-ride.
Occasionally, the rear Derailer would freeze up.
Keeping the bike in working order despite being liberally doused with sand and salt daily.
A lamp with poor charge indicator.