GB4 Universal 400mm Seat Post

I ordered the GB4 post from because I wanted to tip my saddle up a bit. The GB4 post tips the saddle up about 5 degrees compared to the stock post - not too much, just enough. With a Miyata the only way to do that is to change the post or start shimming between the saddle and post, which I wasn’t comfortable with.

The first thing you notice is that it’s really long. Of course that’s probably why most people buy it, but I had to cut it down about 7cm. Not a problem, a regular tube cutter does the job and you can round off the end with a grinder and clean up the inside with a rat-tail file. At this point I noticed a seam inside the post, meaning it was made by bending a plate into a tube and welding it rather than drawing a tube (which would be stronger). It’s steel though, so it should still be plenty strong.

The next thing you notice is that it’s really well made. The Miyata post looks like garbage next to it; the top plate of the GB4 is cleanly cut and very nicely welded to the post, and the plate has a nice even bend. A minor quibble is that the holes for the Miyata saddle, while big enough for the stock Miyata hardware, are a bit small for the 1/4-20 hardware that fit the broached holes in the top plate of the saddle. No big deal, out comes the rat-tail file again, being careful to remove material towards the thicker part of the plate (the holes in the post head are pretty close to the edge).

Finally, when you put it on the saddle you notice that the plate is a bit narrower than the Miyata post head, making it much easier to slide the post head down between the clips onto the bolts.

The only downside is that it doesn’t have seat depth insertion markings. This is no big deal if you set your seat height and forget it, but I’m still finding my best height and I like to drop it a bit for Muni. I made my own marks by (very gently) running the tube cutter around the post to score the chrome.


  • it’s really long
  • it’s well made and should be very strong
  • nice fit and finish
  • narrower head is easier to mount to saddle


  • it’s really long
  • Miyata holes snug for 1/4-20 hardware
  • no height markings


I would have to agree with all these statements. But, I did have to cut the head of it to fit my KH saddle, also the length. I have found the angle to be too much for me. I feel like I’m going to fall off the back, and I keep having to move my feet closer to the crank (pedals don’t feel big enough, cause of the added angle).

I’ve had the GB4 seatpost on my freestyle uni for a couple months now. The only problem I’ve noticed is that the curvature of the top plate on the seat post didn’t quite match that of the bottom of my saddle(Sem deluxe). But when I tightened the saddle bolts, the plate bent just a little, so problem solved (if it ever was a problem). The seatpost seems really strong, and has held up to abuse which my previous Sem and miyata seatposts couldn’t take. It is a little long, though. It would be nice if it were also available in like 350 and 300mm lengths