Shimano 10 speed shifters used with 9-speed drivetrain using RD position B?
So I the possibility of purchasing a set of Shimano 105 10 speed shifters for a great price which I would like to use to eventually upgrade my 9-speed 105 drivetrain to 10-speed. However I just changed the chain and cassette and would like to put them to some good use before doing the full conversion, and would like some more time to be able to search for good deals on 10 speed cassettes and chains. I have heard mixed results doing this using the alternative routing method using position B on the RD shown on SB's page Derailer Adjustment, but it will likely be a temporary solution to get me through the end of the riding season. Does anyone have any experience with using this technique to use 10 speed shifters with a 9-speed drivetrain?
Yes, it can be made to work very well. We set a bike up the other day in the shop using that cable routing with mismatched shifters/cassette, it took a little tweaking with the position of the cable to get it working just right, but in the end it worked just fine. If you try it and it doesn't work perfectly, don't give up, move the cable's position a bit and try it again.
I went through the same thing as you. I ran the alternate cable position and downshifted one click before securing the cable.
Collector of Useless Info
I'm running a 9-speed chain and cassette with 10-speed brifters right now, using the alternate cable routing on the rear derailleur. No issues at all, seems just as solid as my full 10-speed system.