attacco manubrio bontrager comp 31 8mm31. 8 Blendr compatible stem for road, city, and mountain bikes Blendr compatible stem, great for both road and mountain bikes The Bontrager Comp 31. 8 stem is Blendr compatible and provides a secure, versatile connection to 31. 8 handlebars for road, city, and mountain bikes. Product details 6061 T6 forged body construction Removable 4 bolt alloy clamp ensures stiffness and reduces weight 2 bolt opposing clamp attachment for the steerer tube clamp