So I have been building my new bike and it is complete apart from wheels however my rear shock is giving me concerns. It is brand new RS Monarch RT3 that came with the frame.

I have never had a full suspension bike before so maybe just being stupid but the bike on its back the forks compress nicely as would be expected however when I push down on the rear drop outs it is totally solid no compression at all. 150psi in the shock

DAMPING Hydraulic with IFP, External rebound and 3 position Floodgate switch

http://www.sram.com/rockshox/products/monarch-rt3
This one?
Not an owner but you may have the damping set to firm/climb type mode.
Take a look at the blue lever. There may be some more info in the instruction manual (on the link or generally comes with a frame)
If you don’t get any joy with that then I’m guessing it’s a call to whoever you got it from and see what they say about return/warranty process. SRAM UK stuff is normally fairly fast if it is actually faulty.
If it’s from a bike shop you can visit they should be able to take a look and offer some advice on setup for you.

Rebound set to halfway floodgate is set to open.

[EDIT]

Could it be because it is brand new and I just need to get the wheels on and give it a good bounce with me on the pedals?

Try less air (The supplied air charts are sometimes just made up) and the lever in all the positions. If it’s brand new then call the shop in the morning and see what they can do.

[EDIT]

Could it be because it is brand new and I just need to get the wheels on and give it a good bounce with me on the pedals?
Hmm this may help, finish build then try!

Unfortunately my wheels most likely wont arrive until Tuesday.

Sounds like you’ve yet to open the other box of patience 😉

Wait until your wheels arrive and then bounce it.

If the frame is upright and you are pushing down on the dropouts wouldn’t that be extending the shock?

Take the mech hanger off and with the frame the correct way up push on the saddle. Unless your frame has a super low compression rate 150psi should be plenty soft enough for a squidge.

i wouldn’t worry about it.
i’ve recently bought an el guapo with monarch shock and mine’s the same; i haven’t got wheels on it yet but can’t move the shock by pushing the frame with my hands, nor would i expect to be able to tbh.
it’ll work fine once you get it properly built!

slackalice – Member
Sounds like you’ve yet to open the other box of patienc

I know but it feels like forever since I rode a bike!

I_Ache – Member
If the frame is upright and you are pushing down on the dropouts wouldn’t that be extending the shock?

Bike is on it’s back

xherbivorex – Member
i wouldn’t worry about it.
i’ve recently bought an el guapo with monarch shock and mine’s the same

That’s nice to know.

Being new there will be some initial stiction to the seals. Will be fine when it’s built up I’m sure.

Good, good you guys are filling me with optimism. So just need to get these wheels sorted roll it out of the house find that lovely sweet spot and do a nice big hop!

Dare I ask what size wheels? 😉

Try what I suggest anyway. You will be able to compress the shock, maybe not all the way but it will move.