How much effort goes into seat comfort?
Seat design sounds easy: make it comfy. But thereõs more to it than that. The first issue is shape. Shape determines the type of support the seat offers and the freedom it gives to shift position, for comfort or to enhance control. So a dirt bike has a long, thin seat for room to shift bodyweight fore and aft.
On sportier bikes the riderõs weight focuses through two bones called the ischial tuberosities (the bones you feel if you sit on your fingers), so the seat is wide at the back to support, tapering at the front to get feet down Ð a classic saddle shape. Yet despite using arms and legs to support bodyweight pressure points will bring discomfort. So riders need space to shift from side-to-side and front to rear. Cruiser seats are tricky because their riding position puts legs too far forward to support bodyweight. And thereõs no point making a saddle with space to move because you canõt Ð your feet are out in front of you. Itõs a sit-in position, what designers call Ôsocketedõ. What you want is a wide, arse-shaped seat. Most arses are broadly similar; therefore so are most cruiser seats.
This means the manufacturer has to rely on another seat design fundamental: material. In their Commander and Horizon cruisers, Triumph used three solutions. The first was 95mm dual-layer seat foam. The top 15mm is made of lower density foam that feels nice in the showroom. The bottom 80mm is a higher density layer that supports weight (foam density is set by altering the ratio of two liquids that, mixed together, solidify into the foam). Triumph also add a separate wedge of foam, using a third density Ð under the riderõs coccyx as a sublumbar support. They say it combats cruiser back-ache, resisting Ôslumpõ.
The seat vinylõs elasticity and grip has to be right. If itõs too rigid it wonõt yield and may mask the foam, and it also needs grip to stop the rider sliding about.