Are there smaller chain rings available for Shimano Tiagra Triple?
Unfortunately the asymmetric four bolt pattern that Shimano switched to for these cranks is a new patttern and so far there are no small inner rings available. The best advice I can give is to switch to the older five bolt style crank, for which many small rings are available. I use 26-39-50 on the previous generation of Tiagra with no trouble.