Mountain Biking - how to make my aluminum bike less bumpy

I have a Bianchi built with Easton Elite aluminum tubing. It has a rigid fork, I like that, kind of old school.
Other components are also aluminum, like stem, bar, seatpost, nothing exotic. running street tires, and
some older matrix/mavic rims.
However it is very bumpy, vibrations just transmit straight up to my spline. I have ridden stiff
road bike like old school Klein Quantum, but this Bianchi is more bouncy than the Klein.
I am just talking about flat road with less than ideal surface, not dirt road or trail.

I have a carbon bar coming, but I try to stay away from carbon seatpost...

Any remedies??

IMO, there is either something with your wheels or you are just a wimp (not trying to offend you or anything, but...). I used to have a full rigid that I did real mtbing with. I just used the biggest tires I could find and ran them as low as I could.

Edit: You might want to try a new fork. You might just have a really stiff fork.

Bigger tires, lower psi, tubeless if you can (allows really low psi).

FAT tires liek 2.5 low pressure, ergon grips.

You could run your spoke tension on the low end and or get a cushy seatpost. I have a Kent Eriksen titanium layback post that is very comfy.

Thudbuster.

I really want to continue to use my 1.25 street tires. My bike takes a 26.8mm seatpost, hard to find a size from carbon or Ti. What size is more popular with carbon or Ti, I could get a shim.

I really want to continue to use my 1.25 street tires. My bike takes a 26.8mm seatpost, hard to find a size from carbon or Ti. What size is more popular with carbon or Ti, I could get a shim.

Carbon or ti will get you negligible results in the bump transmission department, IMO.

Take 5 psi out of your tires, and if that doesn't work, take 5 more out. If you have disc mounts on your frame/fork, consider switching to BB7 brakes on road wheels. You can run proper road tires, and the wheels will have a wee bit more give to them.

Don't ride a rigid.