Wide spread titanium-toothed cassette
Reviews: Components > Sprocket Cluster / Cassette
Lightweight nine-speed cassette
Staggeringly lightweight cogs
While not strictly part of the Tiagra line, this all- steel cassette would usually accompany this groupset, though you can save weight by fitting the 9-speed version of the Ultegra cassette that uses an aluminium cradle and costs £32.95.