Can a Rear Rack fit on a full suspension mountain bike?

I have a mountain bike with a rear suspension system on it. The back fork is attached to a spring and a piston so that it can give a bit when I hit a bump. Will one of those rear pannier racks fit on it or would it lock itself onto both the wheel and the frame. If it locked to both the frame and the wheel I suspect the up and down movement of the rear wheel would break it.

Sure can IF you get a rack that mounts on the seat post. They have a quick release lever for easy mount and dismounts of the rack.

Here is one example -- there are others.

http://www.performancebike.com/shop/prof...

Be shure that you have good quality seat post and rack if you carry decent size panniers on trails , Axiom made one nice strong seat post rack designed for panniers and affordable .

If you only need to carry a modest amount of gear a seat post rack like McG recommends will work. This type of rack won't support enough weight to carry much gear, though. Plus, be sure you have a good, metal seat post. It'll toast a fancy carbon post in the first couple of rides.

In any case, you are correct. You can't mount a rack that affixes to both the rear dropouts and the seatpost on a full suspension bike.

Basically, you can mount a rack on any two points that don't rotate or move independently.

Depending on the design of the rear triangle of your bike, you should be able to mount a rack that affixes to the rear dropouts and upper seatstays. Or, if your bike is equipped for rim brakes, you can affix the rack to the rear brake bracket. If there is a pivot at the dropout and seatstay, you should be able to affix the bottom of the rack to the lower seatstay.

Personally, I'd recommend taking the bike to your favorite bike shop and get them to help you out.

Hope this helps.

There really isn't a good rack for full suspension bikes.

The seat post mount models mentioned earlier do not carry much weight at all, and as you approach the weight limit they tend to either pivot around the seat post or force the rack, seat post and saddle to rotate in the frame.

Why don't they make a rack for full suspension bikes? Easy. These bikes are intended for off road use... the cheap full suspension models, although intended only for on road have to LOOK like they are off road capable to complete the illusion, so you get "stuck" with the same limitations when it comes to a rack.