I know this isn’t about unis, but some of you might have background in MTBs.
On a XC MTB, is a shock absorbing seat post, like a rock shox seat post necessary? Would it provide any noticable affect for my back, considering there are already shocks built into the forks and one for the rear wheel?
I would think a seatpost shock would be redundant on a dual suspension MTB. People with hardtail mountain bikes like the seatpost shocks (especially as the riders get older) because the seatpost shock makes it easier on their back.
What kind of mountain bike do you have? How much travel in the rear suspension? If it’s a low travel XC racing style bike then the seatpost shock might be useful. Another thing to look at is to make sure your rear shock is tuned correctly so that it’s not too firm or too soft so you get the max amount of cush.
John,
I asked the question as I was looking for an easy and inexpensive fix for my twenty year old Diamond Back Ascent EX Mtb with no suspension.
I thought spending the 56 bucks on a rock shox seat post at price point.com would be a way to go. However, if that didn’t work, I was starting to consider looking at an xc bike. That would leave me with the left over new seat post. Then I would have wasted my money.
That lead me to the question.
The wiser move, looks like it would be to just get the XC bike. I use my MTB bike for scouting trails for MUni and the jaring ride even with low psi, is hard on the wrists, elbow and back.
I tend to use my MTB for the same purpose. To scout trails. I also use it for fun, but I’m not going to admit that here. I’m taking the bike out for a ride tomorrow. 
A bike with no front suspension is going to be brutal. I still remember borrowing a fully rigid MTB back in the late 80’s and riding it on a dirt road and then an easy trail. It was brutal. The dirt road almost killed my wrists. There are some hard core mountain bikers who ride fully rigid single speeds, but they go with a real fat tire on the front, like a Gazz, to help suck up the bumps.
Some of the older riders in the MTB club I’m in have put seatpost shocks on their hard tail XC bikes. The jolts from the hard tail bike were getting to be too much for their back. But now one of them (he’s an ex XC racer) just asked about full suspension. They’re moving to the dark side.
Look around for a good used full suspension bike. There are a lot of good deals to be had on used bikes. Lots of good full suspension bikes out there (along with some duds). You can find some deals on new bikes too. Just make sure the bike fits. It’s no good getting a good deal on a bike that doesn’t fit you.