Originally Posted by bikemig

Tough to beat a 110 bcd crank which you can run as a triple. With 7 on the back and the ride you're talking about (150 miles, 10000 ft climbing), I'd run a triple. I like the old school MTB set up with 46/36/24 rings and an 11-28 7 speed cassette. 11-28 7 speed cassettes are available new even if the supply has been drying up with the pandemic. If you go with a freewheel, 14-28 is the most likely combo new but there are older freewheels out there with 13-28 or even 12-28 but they may be hard to source. Bottom line is first you have to figure out what kind of wheels you are running (freewheel or cassette) as that will likely make a difference as to what kind of rings you want for the crank.

For new 126 OLD wheels, I'd check out what velomine has for sale as well. They have reasonable prices and good products.

For a crank, a 110 bcd crank is your best bet but you'll find more supply at 175 mm than 170 since 175 was a pretty common size on MTBs. The supply of square taper bottom brackets is shrinking but you can still find 68 x 127 BBs. Those seem to work the best with the shimano deore triples I've set up.

For shifters, 7 speed shimano bar ends are a great choice. For derailleurs, just run shimano deore derailleurs.