Chainline Question
 

On older bikes with 6x2 gears set ups, are there chainline issues if you move to a triple in front? The older rear spacing is 126.

Not sure I understand the question. Are you worried about chainring to chainstay clearance? That depends on the frame. Of course, you can always push the chainline out enough to make any frame a triple but then you could have chainline issues; but with 126 spacing you could make it work if you don't cross-chain. Otherwise, just get a new spindle, crankset, FD (and RD if it's short cage) and you'll be good to go.

Hello there might be a bit of an issue in the extreme gear (large front/small rear) provided the innner chainring does not hit the chain stay and the middle ring is close to the same place you should be ok.

I have converted bikes with 2x5 and 2x6 gearing to triples, with good success. You are most likely to have problems with large-large crosschaining, which is why you want the small chainring as close as possible to the chainstay and the small freewheel cog as close as possible to the dropout (allowing for chain rivet clearance, of course).

John, How do I do that, i.e., how do I choose my crank/gear set/wheel dish?