Is that for sure how the 'trickle down' works?
I haven't every heard with certainty that they take their old group (or maybe just the levers), put on a new face, and sell it with a number that's 100 higher... I can see why, since it costs just about nothing to do.. and they only have to upgrade one group every couple of years. The parts go together a little like lego, so it's not hard to figure. It's always been legend and myth when I've heard it. It makes sense, but maybe it's an easy answer to connect dots for people, and not truth.
The way I figure, the difference in actual manufactured parts is only a few dollars when a group gets upgraded (maybe effort springs, return springs, lever fulcrum) which gets amortized over 100,000 or so units per year (I am estimating) so the parts cost is what, five bucks more? Amortized engineering and production tooling costs about the same... not counting bezel and trim differences, and only for one group, change costs aren't really great. This is how I figure that the new Tiagra is so highly regarded, because the old 105 was so good.
IMO, I tried the new 5700 105 and 4700 Tiagra, and 105 had much less effort and less action distance, and smoother. I was very impressed. The Tiagra felt like it needed a lot of distance. I almost wish I hadn't tried that 105.
