I have a broken STI for triple chain ring but still would work for double chain ring. I would like to ask about the measurement of my present bottom bracket spindle used in conjunction with my triple chain ring. I'll be replacing it with a couble chain ring that fortunately I have already. I just need to buy the correct spindle length. I went to LBS this morning but they're clueless about bottom bracket specification.More info:My bike is a road bike and I'm presently using a sealed cartridge bottom bracket with tapered spindle.
Bottom bracket spindle length depends on the actual crank you will be using, and also the frame design. There is no universal bottom bracket spindle length for double cranks, low profile designs can use spindles as short as 102 mm, while other types can be as much as 20 mm longer. If the bike shop you went to has no idea about spindle length, try another. You could also try to see if your crank is sold on the internet, often websites give suggestions for the correct bottom bracket to go with the crank you are buying.
If you pull out the current bottom bracket, you might be able to find the axle length listed on the bottom bracket itself. See the attached link and see if you can find your triple crankset listed in there with the axle length. Make sure you get the right type, octalink vs. square taper vs. external bearings. Also, you will most likely run into some issues since your left shifter is made for triple cranks instead of a double crankset. The cable pull may not match up correctly. Your front dérailleur will most definitely require some adjustment. Why not just replace the broken chainring? They're relatively cheap. Don't want the embarrassment of being the guy with triple crankset? The triple-double conversion is rarely worth the cash and effort.
