Do frames with forward facing dropouts essentially have a variable chainstay length? My understanding is that chainstay length is measured from the center of the BB to the center of the rear axle. My droupouts are easily 3cm long so there is quite a bit of fore-and-aft space to move the axle.
My bike will be set up with a rear derailleur and 9-speed cog. Will the LBS have some latitude in deciding where to place the axle? I assume chain length dictates some of this but I don't know how small the increments can be when removing links. Will there be one spot that works, based on chain length, or will there be several spots that work?
I bring this up because I've been riding a bike with 43cm chainstays. This frame is listed as having 43.6 cm chainstays. I've been curious about the effect of longer chainstays so if shoving the axle as far back as possible would give a longer CS length, I might want to experiment with that. Measuring from the BB to rear axle when all the way back in the dropouts is in the 46cm range, although I may not be measuring along the correct axis (ie, my meausurement was along the chainstay, rather than a straight line).