I'm just in the process of putting a shed up on a gravel base, so I'm thinking of digging a hole and putting a D lock in the hole in the 'U' shaped way, filling the whole with concrete.

At an old house I had a ground anchor screwed in to the concrete but it was always low down and a pain to unlock/lock

Will the rubber coating on the D lock be a problem?

No, but it'll be dead easy to break out. You'll need to anchor it in with some rebar or something similar.

make sure you put the locking end into the concrete so you have a loop sticking out ready for a chain to slide through.

What PP said

If you thread a couple of bits of steel re-bar through the U before back-filling with concrete you will get a lot better pull out strength. Would also fit the Lock head to the U while casting to make sure you dont get any deformation

If you anchored the U end in concrete, it'd take ten seconds to jemmy the other end off with a big long crowbar or pole.

Get a proper ground anchor, and chain. You can get long stake things designed to be set into concrete.

The whole point of locking anything in a shed though is only to delay them taking it.

If its your opportunist they will just carry a crowbar etc at most, and a D lock set in concrete will with stand that.

However if some one really wants your bike they will get it whatever.

A ground anchor might be strong but the cable/lock attached to it is surely the week point?

Personally I'd set the whole lock in the concrete – with the 'u' end sticking out to anchor to.
To give it more setting strength, I'd wrap some simple chain around the 'flat' end (no need to lock it to it, just wrap it around a few times) before pouring the concrete over that. The chain wrapped around it will make it harder to simply pull the lock out of the concrete.

DrP

what DrP said plus I'd smear the lock with lots of grease or wrap it in loads of duct tape or soemthing – concrete's pretty caustic stuff.

Can you simply set the bike into the concrete?

I would just concrete your rear wheel in. Sorted.

Just fill your entire house and garage with concrete. Sorted.

concrete's pretty caustic stuff.

It is, yes, but don't do that! Every single concrete structure you see has metal (Usually mild steel) in it. The concrete won't attack it.

BUT if water can get to the steel, the steel rusts and cracks the concrete as it expands. All you're doing by trying to cover the steel is giving water more of a chance to get in. As long as you use plenty of cement when mixing your concrete, and not too much water (Keep the mix nice and stodgy) then tamp it down in layers as you fill the hole, it'll be fine.

PS – I got qualifications in concrete. I know my stuff. 🙂

I put a ground anchor in our shed.
Ordered online
The business..
J.

"I got qualifications in concrete"

What was your aggregate score?

😉

Almax chainsUse one of these chain/lock combo's…

I keep ummming and aaahing about getting one of these.

http://www.yanchor.com/

If you google 'ground anchors' there's another security website that does a similar thing, but it's a curved pipe, rather than a Y. They also sell some reet chunky chains & locks too.

Found it – http://www.torc-anchors.com/proddetail.php?prod=ConcaveAnchor