switching crankset for Surly LHT
 

I've become so accustomed to a double with 172.5 arms that I'd like to change the 175mm Sugino triple on my LHT to a 172.5 double with 34/46 rings. So here's the question, are all square tapers the same should I find a 110 BCD road set, or should I be looking at a whole new bb for a double.

And just to complicate the switch I'm thinking of a road triple (to get the 172.5arms) and putting a bash guard instead of the outer ring. In that case could is it possible to put a 34t on the 74mm inner ring and a 46 on the middle?

Are you making this switch solely based on 2.5mm of crank arm length?
I have bikes with crankarm lengths ranging from 165mm (fixed gear) to 175mm (mtb) and every length in-between, and I honestly can't tell much difference among them.

oh no,,5mm when you add the two together

Wow. That's a lot of thought and consideration just to go from 172.5mm crankarms to 175.

Just get whatever gearing you want, and if it's different from what you already have, make sure to get 175mm crankarms if you have to change the cranks. If you like your current gearing (it's not clear if you do or not, just that you don't like the 172.5mm crankarms), stick with what you have. Or if you can, just switch out chainrings on the current cranks.

If you change to a different model crankset, yes, you'll likely need a different bottom bracket. And yes, you can put a 34t ring on a 74mm BCD crank-

reverse, the triple is 175mm and I want 172.5, my regular touring bike has 172.5mm double just like the road bike I've had for 24yrs.

Either way, I'm afraid it's all in your head.

thanks for the help guys