2011 Tomac Diplomat 29 Frameset

The difficulty with producing a nice-riding full-suspension 29er is getting everything fitted nicely around the big wheels and long travel. But overcoming those constraints is also what makes the Diplomat such a nice riding bike.

For example, just to make the chainstays as short as possible, we designed a removable seat stay arch and attached the front derailleur directly to the chain stay yoke. This allows us to keep the chainstays at 17.5 inches, one of the keys to making the bike nimble handling.

The Diplomat uses our proprietary IAS suspension system. IAS is a simple yet effective system that improves overall suspension action without sacrificing pedalling efficiency or rear end stiffness. With IAS, a CNC machined link between the rocker pivot and seat stay end, carried by high end full-compliment bearings, allows the rear shock to initiate more quickly and the suspension to be more responsive. IAS suspension makes quick work out of bumps, especially repetitive hits (think braking bumps) where quick suspension action means less transmitted to the rider.

The Diplomat's main pivot is located so that it maximizes pedalling efficiency, but not in a place that would create excessive pedal feedback or minimize the bike's ability to absorb bumps. We used a Fox RP23 shock with XY secondary air canister because it's more linear from middle stroke and has low initial stiction (because you are running lower initial pressures). The Diplomat has a relatively flat shock rate, which maximized the character of the air shock. It allows the bike to pedal well, get full travel and still feel bottomless throughout the travel.

With the larger wheels, another major factor is getting sufficient stiffness in the frame. Because the swingarm typically sees the majority of lateral (side to side) flex, the Diplomat uses a fully triangulated rear swingarm to increase stiffness. Stiffness in the swingarm translates both into better rider control, but it also allows the suspension to be more active in rough terrain. When the rear end is suffering from lateral flex during suspension movement, it binds the shock and will limit suspension movement. The front triangle has also been designed with stiffness in mind. The top and down tube are specially shaped to maximize lateral stiffness, and are triple butted to ensure minimal weight.