The Tiagra chainset is now a two-piece design and is outwardly similar to the Hollowtech II components further up the Shimano range, but with cost-saving C-section crank arms that are available in 165mm, 170mm and 175mm lengths. The chainrings have ramped and profiled teeth that shift the chain very smoothly under pressure, but the two outer chainrings - also used on the 105 chainset - wear more rapidly than the machined ones found on the Ultegra chainset. As well as the 30-39-50 triple, the chainring options available are 39-52 (double), and 34-50 (compact), both of which cost £10 less.
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