Originally Posted by southpawboston

I think Justin nailed points 1-3 on the head.

Just a couple of comments I'll add-- if you decide to file the teeth off your existing 54T outer ring to create a chain guard, then you won't have to purchase new double-chainring bolts, which might otherwise set you back $20-30 (I haven't checked prices recently). Also, keeping a pseudo triple/chainguard setup, you will only need to buy one 44T inner ring, which is cheaper than buying a new outer ring with the same number of teeth. So converting the outer ring to a chain guard can potentially save you some money, or at least offset the cost of having a machine shop do it for you.

Also, if you stick with double ring + chain guard (triple), you will need a longer spindle. Figure around a 122mm. I have several TA crank setups, and the one I have closest to what you are proposing is a 46/26T double. For that I'm using a 115mm JIS spindle and a 1.5mm spacer on the driveside. That leaves me with just about 2mm of clearance between the inner chainring teeth and the chainstay. Close, but that's how I like it.

Lastly, since the Q factor of the TA cranks is so low, if you are running a 10-speed cassette, you may get interference between the chain and the tip of the drive-side crank arm as the arm rotates past the chain when in the smallest cog. This will most likely occur if you run a double configuration on a 115mm spindle, but if you go with a 122mm spindle / triple setup, you should not have this problem. With my TA double on 115mm spindle, the chain just clears the crank arm by about 2mm when on the smallest cog of an 8-speed cassette. Rear spacing is 130mm.