Triathlon / TT Bike Cassettes & Cogs

Narrow-range cassettes like 11-23t or 12-25t are best for flat or rolling courses because the close steps help you hold high speed. Wider options such as 11-28t or 11-32t give larger low gears for hilly tris so you can maintain cadence without grinding on climbs.

Make sure the cassette matches your drivetrain speed (10/11/12-speed) and that your rear derailleur can accommodate the range. A mid-range 11-speed cassette like 11-28t usually pairs well with a 52/36t setup, while very wide ranges may require more derailleur capacity.

Shimano Ultegra 11-28t is a great all-around pick for mixed terrain thanks to smooth 11-speed shifting and balanced ratios. Shimano 105’s 12-30t gives a slightly wider range that helps on steeper climbs if you prefer easier gears over the tightest spacing.

An 11-32t 11-speed cassette can work with a 53/39t chainring if your derailleur has the capacity and the B-screw provides clearance for the 32t cog. Expect much easier climbing with the 32t compared to narrow-range cassettes, but confirm your derailleur spec to avoid shifting or chain-wrap issues.

Most TT cassettes use high-grade steel cogs with nickel-plated or chrome finishes for corrosion resistance, while premium models use alloy or carbon carriers to save weight. Shimano cassettes are noted for durable cog materials that resist wear under heavy triathlon training, so pick a steel-cog cassette with an alloy carrier if you want a balance of lightness and longevity.