Upgrading Shimano Tiagra shifters
Newer versions of Tiagra brifters route the shift cable under the bar tape. Do be careful though because Shimano has changed their cable pull on some versions. The 4700 series Tiagra uses a cable pull ratio that is different from any other Shimano models. If you get 4700 brifters you would need to replace your derailleurs to be compatible.