IRD skillfully designed this post ten years ago and the clamp style has been copied by others since then. The style of clamp assembly permits minute adjustments in the head angle, while preserving the sturdiness needed in a light weight aluminum seatpost. It uses two upper clamp pieces, (with 1/2" of rail grabbing surface) that are made of extruded and machined aluminum, drilled through in the middle from top to bottom. In the drilled hole a steel nut insert is pressed, so a bolt from the bottom has a hard, threaded surface to grip. The lower clamp piece, (with a 1 7/8" of saddle rail support), is turned on a lathe, drilled through to make rail supports and reduce weight. The head piece is sturdy aluminum tubing that has been "miter" cut (that is cut to fit the shape of the lower clamp piece's rounded bottom side). The bottom of the lower clamp piece is rounded so that "rocking" it forward or back, on the head piece, provides the angle adjustment for your saddle.
To hold the clamp assembly, saddle and all this adjustability in place, there is an aluminum rod through the head piece that has been drilled vertically at both ends. Through each of these holes, passing upward, is a 5mm by .8mm thread pitch, steel cap screw. The bolt is 38mm long and has a 4mm allen head. The bolts thread into steel nutserts pressed into the upper clamp pieces, from the top, producing a vise-like grip on the saddle rails. The head piece is pressed an inch and a half into the aluminum tubing section. The tubing section is precision lathed to provide a perfect fit to the seat tube. The IRD 375 post is available in two colors, with the clamp and head piece painted Black on a Silver anodized tubing section, or with the clamp and head piece painted Black on a Black anodized tubing section. With the clamp perpendicular to the tubing section, the center of rail to end of tube length is 372mm.
The weight of a 27.2mm IRD 375 post is 297 grams. The IRD is made in Oregon, USA, and is available in, 26.4mm, 26.6mm, 26.8mm, 27.0mm, 27.2mm and 27.4mm. Specify Black or Silver and the diameter.
No longer made, we sold these posts for $59.99
This is the same seat post in design and manufacture as above, except the aluminum tubing head piece is made longer, and it is inserted 1 3/4" into the aluminum tubing section for extra safety. The IRD 425 post is available with the clamp and head piece painted Black on a Black anodized tubing section. With the clamp perpendicular to the tubing section, the center of rail to end of tube length is 431mm. The weight of a 27.2mm IRD 425 post is 335 grams. The IRD 425 is made in Oregon, USA, and is available in, 26.4mm, 26.8mm, 27.2mm, 28.6mm, 29.4mm, and 31.6mm sizes. Specify diameter.
No longer made, we sold these posts for $119.99