Originally Posted by
oldbobcat
I've worked with 4700 plenty of times and never had issues with it. In fact, that's what's on the Trek Emonda 3 that I bought my daughter a few years ago. But that was with double chainrings.
Although it is advertised as working with cassettes with largest cog between 25 and 34 teeth (on triple), it looks that Tiagra GS design can only shift crisp with cassettes with largest cog around 30-34. With smaller cassettes, shifting progressively deteriorates because B adjustment can not compensate the increased distance between upper pulley and cassette.
I use SRAM Force 22 for years and I have almost 100% crisp shifts with 2 cassettes: 11-26 and 11-32, because B adjustment is very effective. I obtained similar 100% crisp performance with low end Microshift 8 speed, 12-25. But Tiagra 4700 hesitates around 30% of shifts with 12-26 cassette. I would say it is simply a design flaw where B screw cannot compensate for smaller cassette, although the manual says it should work (in fact it works by shifting all the range, but with very low / hesitating performance).