I thought I read or was told the lower level GRX calipers and Tiagra were very similar if possibly identical except for the branding - ? - but I have not compared them
the upper GRX 800 series caliper uses ceramic piston (similar to 105 / Ultegra) - the lower level GRX uses resin piston (same as Tiagra) ... ?
GRX calipers might use different hose attachment (banjo vs straight ?) - again not sure / can’t recall
Tiagra calipers are flat mount and accept the finned pads ... ‘narrow track’ ... (same as GRX ?)
currently in the final steps of Sora 9 to Tiagra / GRX / etc conversion ... GRX FD is definitely different compared to other Shimano FD’s ... additional setup steps and adjustments ... cable routing is even unique (after it exits the securing pinch bolt) - loops and passes through a small plastic top cover that snaps into place
Last edited by t2p; 04-03-23 at 08:42 AM.