Originally Posted by
grumpus
"Performs best when combined with inForm IsoZone grips" according to Trek - it doesn't seem likely there's anything special about the shape or size of the bar where the grips fit, just that the bar has an internal custom butted profile to improve comfort, with the specific grips tuned to offer additional damping. Allegedly.
Unfortunately the bars have a unique diameter. Ergon confirms this and advises Trek customers accordingly.