The Montague Octagon adjustable steer tube extension allows you to quickly and easily adjust the height of your handlebars - up to 4" - without tools.
Octagonal shape keeps steering engaged while raising and lowering the stem.
Automatically maintains minimum insertion.
Clamps to top of steerer, your original stem clamps to top of Octagon device.
Due to variations in aluminum steerer tube wall thickness, the manufacturer specifies usage only with 1-1/8" threadless steel steerer tubes.
Must be installed by a professional bicycle mechanic.
Note: The height of the stem may be limited by brake/shift cable length, which is only one reason why this should be installed by a professional mechanic. This does not include a stem or handlebars.