General Cycling Discussion - Suspension Seatpost

Has anyone used or have any experience with this seatpost? It is a Rock Shox GPS. Most of the Rock Shox have the blue paint on them but this one is black which i want.

I don't really want a blue seatpost on my all black bike. I know all about the Thudbuster but I don't want it. It is too expensive and i like having seatpost room for seatpost attachments.

I also know that many don't like S-Seatposts. I am ready to give one a try. I don't ride any technical trails but do ride a lot of bumpy gravel roads. I just want to take the sting out a little.

Also it looks like i will have to shim nearly any seatpost that i buy because i have a 31.6mm and I can't find a S_seatpost that is that big. Is shimming a BAD idea? It seems a little rigged to me.

that looks tight! i wouldn't mind investing in that.. where can i buy that one from and what's the price??

BIKENASHBAR (http://www.nashbar.com/profile_moreimages.cfm?category=117&subcategory=1187&sku=9025&brand=)

that's not bad for $40. i was thinking about getting a suspension sitpost and then get a suspension front fork for my bike... :D

I had the blue one on my hardtail MTB for about four years. It was pretty good. It takes the edge off of the vibrations and if you are seated (by mistake) and take a hard bump, it really helps.

They do take a little maintenance. You need to take it apart, clean and regrease it fairly often.

I wouldn't get the GPS. That is the bottom basement meant for hybrids post. I have also heard that the shims suck. You can get the MTB one in 31.6mm and the RS web site says they are now grey. I would not buy the crappy one just to get black.

Has anyone used or have any experience with this seatpost? It is a Rock Shox GPS. Most of the Rock Shox have the blue paint on them but this one is black which i want.

I don't really want a blue seatpost on my all black bike. I know all about the Thudbuster but I don't want it. It is too expensive and i like having seatpost room for seatpost attachments.

I also know that many don't like S-Seatposts. I am ready to give one a try. I don't ride any technical trails but do ride a lot of bumpy gravel roads. I just want to take the sting out a little.

Also it looks like i will have to shim nearly any seatpost that i buy because i have a 31.6mm and I can't find a S_seatpost that is that big. Is shimming a BAD idea? It seems a little rigged to me.


My wife rides one and she seems to think it is okay. We had to shim hers and have had no problems

I had the blue one on my hardtail MTB for about four years. It was pretty good. It takes the edge off of the vibrations and if you are seated (by mistake) and take a hard bump, it really helps.

They do take a little maintenance. You need to take it apart, clean and regrease it fairly often.

I wouldn't get the GPS. That is the bottom basement meant for hybrids post. I have also heard that the shims suck. You can get the MTB one in 31.6mm and the RS web site says they are now grey. I would not buy the crappy one just to get black.


Anyone have a link to that seatpost? (the 31.6mm in grey) The RockShox website doesn't show it.

Here you go:

http://www.rockshox.com/seat/mtb.asp

I just looked closer. It is grey. But, it says SHIMS fos 31.6mm. Sorry for the misinformation.

Here is what it says:
MCU bumper: For superior rebound and reduced topout
Easy Adjust: Spring preload and MCU length helps fit a wide range of rider weights
7000 series aluminum tubing: lightweight, stiff and strong
Gray Anodized with laser etched graphics

Travel: 50mm
Weight: 390g
Spring: MCU
Adjust: Preload
Damping: MCU
Sizes: 26.8 or 27.2mm
Length: 350mm
Shaft: Alloy
Body: 7000 AL
Colors: Grey
Options: Shims 28.6, 30.9 and 31.6mm

So what about shimming seatposts? Has anybody tried it? Does it work?

sorry to be a newb.. but what is the purpose of shimming a seat post? is it like a width adapter or something? cuz i measured the seatpost hole from the bike frame, and it's at 30mm. so should i buy the 28.6mm model from Rock Shox, or should i getthe 30.9mm model? please teach me. thanks.

I have had no trouble with the shim for my seat post.

ruirui,

The shim makes up the differance between the size of the seatpost and the inside of the seat tube.

Pull your seat post out and look for the size stamped on it. I would trust that more than a measurement, unless you used calipers.

ruirui,

The shim makes up the differance between the size of the seatpost and the inside of the seat tube.

Pull your seat post out and look for the size stamped on it. I would trust that more than a measurement, unless you used calipers.

ok, i'll check for that stamped marking. but yeah i was using my dial calipers when i measured it. thanks for the help!`

ruirui,

The shim makes up the differance between the size of the seatpost and the inside of the seat tube.

Pull your seat post out and look for the size stamped on it. I would trust that more than a measurement, unless you used calipers.

Avalanche325, i've checked my seat post. it has 30.4mm stamped on there and total length is 95mm, i think. but for sure it's 30.4mm. so should i just get a seat post suspension with 27mm or 29mm? would i still need a shim?

Avalanche325, i've checked my seat post. it has 30.4mm stamped on there and total length is 95mm, i think. but for sure it's 30.4mm. so should i just get a seat post suspension with 27mm or 29mm? would i still need a shim?


I know this is a slightly aged post: but yes, you need a shim. If you try to tighten down to a smaller size, you're going to damage your frame.

I know this is a slightly aged post: but yes, you need a shim. If you try to tighten down to a smaller size, you're going to damage your frame.

How timely! How much smaller? I have recently wanted to put my 26.8 post into my 27.2 frame. It's pretty close but like you said I didn't want to damage my frame. The 27.2 frame is aluminum. Does this small size difference need a shim? I went Nashbar and left a little confused with my numbers vs theirs. They talk of converting a 25.4 to 27 or so. Thanks for any input. Charlie

I'd definitely use a shim; they make them in all different sizes, and considering teh expense versus the cost of a new frame, I myself just wouldn't take the gamble. If you've got an aluminum frame, you risk cracking it by trying to crank down to a smaller size; steel won't crack, but you'll force the seat tube out of round, which will make it difficult to use a properly fitting post in the future...

If you can't find a shim to fit, you might experiment with using a piece of a soda can to make your own... I haven't done it, but I know people who have!