Chris_F

I posted this over in the road bike forum but it was suggested that I post it here instead (sorry about the double post, mods feel free to delete the one in Road bikes).

I'm thinking of switching my triple crank out for a double. I've got Shimano 105 shifters. Can I just use the same shifters and set the Der stops to accommodate the double or do I need to get new shifters? I assume I can use the same front Der (Shimano Tiagra)?

Retro Grouch 

How many cogs do you have in back?

Shimano rates their 9-speed shifters as either double or triple compatible. I don't know what the exact difference is. If it was my bike I'd give it a try and see if I could make it shift to my satisfaction.

FWIW, I own two bikes with Ultegra 9-speed shifters. On the tandem triple I get 1 shift position for the granny, 2 shift positions for the middle ring and 1 shift position for the big ring. The klein double has 2 shift positions for each chainring. Both bikes have flight Deck computers and both indicate the appropriate chainring in all shift positions so I know I've got them set up as Shimano intended.

Chris_F

I've got 9 in back. Thanks, didn't know the shifters did both. IIRC there are four stops on the front shifter just like you indicate.

JiveTurkey

If the shifter works for a triple, it will also work for a double. You'll need to decide which two of the three positions to use on the shifter. There are pros and cons of using either inner/middle or middle/outer.

The front derailleur should be fine.