Can suspension be set up for a 330# rider.I don't mind sending it out for special work if necessary.This is for the street and smooth trails no off road its just to ease my back.
I'm looking at a FS 29er or a Bluto equipped fat-bike or just a fat-bike if the suspension won't work or deemed unnecessary for trails.
I have ridden 26inch rigid mountain bikes and love the handling but is too harsh on a arthritic spine.

I don't have a definitive answer for you, but I would think that since the rear wheel carries the greater share of the rider's weight, an air sprung fork should be able to compensate.
Edit: Just realized you may be talking full suspension. No idea about that, but having test ridden a fat bike, I can tell ya that those monster tires run at low pressure will smooth the ride considerably.

Short answer - Yes --- Maybe.

Many can be set for the added load, but it may come at the expense of travel. Most bikes are leveled by compressing the spring more (added preload). On many (most?) suspensions the spring is short enough that over compression can compress it to where the coils are fully compressed.

Air shocks may do a better job handling the added load, but in all fairness, you'd have to ask the question on a case by specific case basis.

Long travel Fork, air-oil, can have travel left after pumping up the pressure so pre load sag does not take up most of the travel .

but for the riders use 'street and smooth trails', that is over spending .. just rely on the fat tire and stick with a rigid fork ..

your arms are pretty good shock absorbers if you dont straight-arm and lock your elbows.

330 pounds exceeds the weight capacity of the Cane Creek suspension seatpost, so thats Out.

Maybe a super wide tires will do with its air volume in the 4" wide tires

Sun Crusher , comes wit smooth tread Street tires where the Pugsley ships with knobby.

so there is practical options

I agree with Bob. For smooth trails/pavement, let fat tires be your shock absorber.
You can also get out of the seat for bumps and "ride light" when needed.

I have ridden at weights from 300 - 365 and have found that higher volume tires are better than a shock.

I don't have a bad back, so I can't say for sure how it will work for you, but going with large volume tires at near max pressure provides good comfort for me.

Going with as low a pressure as you can without pinch flats helps the comfort level too.

I haven't ridden a fat bike, but the few people I have talked to that ride them, they say they are wonderful for rough terrain, but even at relatively high tire pressure (for a fat bike tire) they are pretty sluggish on pavement or smooth trails.

I think a non suspended fat bike could be ideal for you, the big tires do a lot to smooth out the ride and rolling resistance is much better than you would expect.

If you end up with suspension, Rock Shox has what is called "bottomless tokens" for a number of their forks (bluto included) and it would be worth using as many as the fork can take. In short they will reduce the volume on the air spring causing the air spring to become stiffer quicker as you go through your travel.

I would love to have a 29er with full suspension for the lower rolling resistance but I guess it will wait till I peel off the pounds.I have a super road bike but until I break 250# she will gather dust.I'll order a fat-bike next week and get some road tires for it.I'm new again with bikes but feel secure with the experience shared on this forum.Here's the winner what do you think!