I want to change my gearing. I have a Sugino XD600 26-36-46. I want to switch the outer and middle chainrings for 44 and 48. I was thinking of buying TA chainrings, because I hear they last long enough to pay for their higher price. However, Peter White Cycles says TA rings don't work well with Sugino cranks. Assuming I buy 48 and 44 tooth chainrings and keep my 26 tooth ring that I already have, what do I need to do to make sure what I buy works with Sugino?

How many bolts do your cranks have? You'll need to match the bolt circle diameter with the chainrings you want (BCD).

After you know these two things, just search for the rings.

For example, my crankset is a 4-bolt shimano SLX mountain crank (triple) 22-32-44. The BCD is 104 for the middle and outer ring, and 64 for the inside ring.

So I would need to find 2 chainrings of the tooth size I want, in the 104 BCD and the other chainring as a 64 BCD.

Also, note that your front derailleur is matched to certain sized chainrings, so changing them around can sometimes affect shifting. If you change the middle from 36 to 44, I would venture a guess that your current front derailleur will rub on the middle chainring and not shift very well.

For a 26-44-48 you'd probably need a standard double front derailleur instead of a triple, since your're wanting rings closer to half-step gearing.

According to Mr White, the compatibility issue you are concerned about exists when you use a TA inner ring on a Sugino triple, since the TA rings are made to the Shimano standard which puts the teeth of the inner ring slightly further inboard than does the Sugino inner ring. Since you'll be using your 26t Sugino inner ring...and only replacing the middle and outer ring...you shouldn't have an issue.

TurbineBlade: My cranks have 5 bolts in a 110mm diameter. I know about the need to switch to a double derailer, and I am indeed going for half-step plus granny.

desertdork: Makes sense; thanks for the help.

Question two: Peter White sells outer, middle, and inner TA rings. Harris Cyclery just sells TA rings without specifying where they go, but they're much cheaper. What is the difference between outer and middle chainrings, and why would one seller distinguish between them while another wouldn't?

The difference between middle and outer chainrings from TA is which side the ramps and pins are in relation to the recessed side of the bolt holes. An outer chainring will have the printing on the outside of the ring as well as the recesses for the chainring bolts, with the pins on the inside. A middle chainring will have the printing on the outside, but the bolt recesses and ramps on the inside. The tooth offset is also a little different between the two. We don't carry the 44T middle, but Peter White does.

On our 110 BCD chainring page, the chainrings are differentiated between inner, middle and outer rings:
https://www.sheldonbrown.com/harris/chainrings/110.html

Oh; I didn't notice. You're right of course. Too bad about no middle 44-tooth, though.