I have a 26-36-46 on my new LHT. It will be great on tour, fully loaded, climbing steep hills, and I'd even like to try a 24 or 22, but around town I'm missing my 50-tooth top chainring. My top speed on flats or slight downhills isn't very fast. I think I'd really be frustrated with a 42.

I'm going to look into buying two sets of chainrings - one for around town and one for tours. I typically go on only one serious tour per year in the summer. I wouldn't mind a few hours making the switch if I didn't have to do it too often.