For the 2020 model year, Shimano has upgraded its entry-level Tiagra road components with new designs that are more ergonomic and offer better performance. The new line will see upgraded Tiagra-branded components that replace former non-series components and more premium features and form factors cascade down to this entry group. The components will be available in June 2019.
New DUAL CONTROL (brake/gear) LEVERS (ST-4720-L/R) replace the previous non-series ST-RS405 units and now follow the pattern set by premium Dura-Ace, Ultegra and 105 groups that utilize a slim body to house the hydraulic disc brake controls and increased adjustability for optimum bike control.
The TIAGRA 10-speed shifting mechanism within the lever body has also been upgraded from the non-series levers to provide quicker rear gear shifts thanks to a redesigned internal shifting unit. An optional extra feature with the new TIAGRA Dual Control Levers, also found in new 105 and Ultegra ST levers, is a version with a short reach lever and more outboard profile (ST-4725-L/R) for riders with smaller hands.
A lower 48-34T front chainring combination for the TIAGRA FC-4700 2-piece crankset now appears alongside the existing 52-36T and 50-34T cranksets. This smaller ratio closes the gap to 14T between the big ring and small ring, reducing the number of compensation shifts needed in the rear cassette and making TIAGRA more in line with a wider number of riders.
Finally, a new 12mm E-THRU hubset (HB-RS470/FH-RS470) for disc brakes appears at TIAGRA level. When combined with compatible frames, thru-axles increase the rigidity of the wheel and allow for more accurate alignment of disc brakes. This 10 or 11-speed hubset is available for 28H or 32H rims and comes with a disc brake-specific O.L.D. of 110 and 142mm respectively.