Starting with a frame and building it into a complete bike is generally for people who either already have a complete bike and are looking to upgrade the frame or people who have somewhat eclectic tastes and prefer a custom build. Having the right frame pays off. Building the best triathlon or tt bike from components might take more work, but if the resulting ride makes you happier by being exactly what you want, the effort is worth it. A big reason people switch frames is to get either a more aero frame or a better fit because bodies change with fitness and age. The best triathlon and tt bikes are not only fast, but fit right. Used triathlon bikes are usually great deals and are in great condition because they aren’t typically subject to the abuse that other bikes get.
A time trial bike frame is almost indistinguishable from a triathlon frameset. We have a detailed explanation. The key is that “time trial” refers to a discipline of bike racing, and, as such, tt frames are subject to certain design limits. But those parameters also work for triathlon bikes; many make one that does both.
We have more used triathlon bikes and framesets for sale because simply more people do triathlons. It’s also why there are beginner and entry-level triathlon bikes. The features that generally distinguish tri-specific frames from tt-specific are more dramatic aero shaping of the frame, more on-bike storage options, sometimes more adaptable handlebar/extension systems. That’s why they’re often referred to as modules, like the Felt 1A frameset, which includes accessories with the frame. There’s lots of triathlon gear; much of it can be fitted to the bike.
Trek has been making cutting-edge time trial and triathlon bikes since 2000, when they debuted their carbon TT bike frame, the Team Time Trial frameset, then the TTX. That was succeeded by the Speed Concept in 2009, and it has been their tri’ bike platform ever since, with 2022 showcasing their third iteration. As time has gone on, component integration has increased, storage has increased, and aerodynamics have improved. They even added comfort: the rear end has an IsoSpeed decoupler.
Cervélo’s debut bicycle was a cutting-edge aero ride, the Baracchi. The Baracchi was so far-out in its design, that it was banned. Today, their PX-series comes close to that original, while the Cervélo P-series frames have a highly refined, if somewhat conventional design, something you’ll see doing double-duty as time trial bike frames.
Specialized got into the tri’ bike game in the early ‘90s with the Transition, one of the first mass-produced bikes built with the steep seat angle we now expect from the category. As they developed new iterations, the tubing got ever more shaped by the wind tunnel, with handlebars, aerobars, seatposts, and storage systems becoming integrated. Now they both have the tri-specific and tt-specific Specialized Shiv disc frameset.