At 148 pounds, Ossa's new trials bike the TR 280i is as light as it looks. What isn't as apparent is what was done to make the bike so light.
First, the 272 cc two stroke engine is tilted back at an extreme angle and facing the wrong way. This arrangement allows for a forward facing airbox and intake manifold.
Second, the exhaust appears to be part of the subframe. Erik Buell experimented with incorporating an exhaust manifold into a swingarm but I have never heard of using the subframe as a manifold.
Third, close tolerances, just look at the exhaust manifold snake around the Ohlins shock. Marzocchi handles suspending the front forks.
Fourth, the radiator is located behind the gas tank. I'm not sure how this could help save weight but it does reduce a motorcycle's frontal profile not that that is important in trails riding. The combination aluminum and chrome molybdenum steel
frame is nice too.