How do I fit a ground anchor for a bike or a mower?

Choosing an anchor that matches the chain, getting the fixing into something that will actually hold, and the mistakes that leave an anchor stronger than its own fixings.

Difficulty: intermediate
Time: 2 hr
Read: 4 min
Safety: caution

Short answer

Match the anchor and the chain to the same security rating, fix into a concrete slab or solid masonry rather than a timber shed floor, and use the security fasteners supplied with resin or through-bolts. An anchor is only as good as what it is bolted to, so the substrate decides the whole job.

Bikes, mowers, motorbikes and power tools are stolen because they can be picked up and carried. An anchor removes that, and it is one of the few security measures where the product's rating genuinely maps onto the outcome. The failure mode is almost never the anchor — it is a chain that does not match it, or a fixing into something soft.

Safety

Check for buried services before drilling any floor — a garage or shed slab can have a heating pipe, a drain or a cable in or under it. Use a detector, and never drill blind near the wall line. Wear eye protection and a P3 dust mask when drilling concrete, and use dust extraction or wet drilling where you can.

What you'll need

A rated ground or wall anchor
A chain and lock of matching rating
SDS drill with the specified bit size
Resin anchor capsules or the supplied bolts
Cable and pipe detector
Dust mask and eye protection

Step by step

Choose the anchor and the chain together.A Sold Secure Diamond or Gold anchor with a low-rated chain is pointless, and so is the reverse. Buy them as a matched pair to the same rating, and check the chain will actually pass through both the anchor and the bike frame.
Pick the position before you buy.Somewhere the chain reaches the frame — not the wheel — with the item close to the wall or floor, so there is no room to work on the chain. Corners are good; the middle of a floor is not.
Assess what you are fixing into.A concrete slab at least 100mm thick, or solid brick or blockwork. A timber shed floor holds nothing useful. If the shed has a timber floor, fix to a concrete base beneath it, or fit a wall anchor into the masonry of the house instead.
Scan for services.A cable, water pipe or underfloor heating loop in or under the slab. A garage slab may have a drain run near the wall. Use a detector and take the extra ten minutes.
Drill the specified hole, exactly.The anchor's instructions give a bit size and a depth. Deeper than specified is fine for resin; the diameter is not negotiable. Clean the hole thoroughly with a blow pump and a brush — dust in the hole is the commonest reason a resin fixing pulls.
Use resin where the substrate allows it.Chemical anchoring spreads the load through the surrounding concrete rather than wedging against it, which suits a slab near an edge and old, slightly friable concrete. Follow the cure time before loading it.
Use the security fixings supplied.Shear-head, clutch-head or ball-bearing-capped bolts, or bolts that are covered by the anchor body once fitted. An anchor held on with ordinary hex bolts is undone with a spanner.
Chain through the frame, off the ground.Through the main triangle of a bike frame, not the wheel, and keep the chain up off the floor so there is nothing to rest a tool against. Slack chain lying on concrete is the classic mistake.
Anchor more than one item.A single anchor can take several bikes on one chain. Two anchors on opposite walls of a shed cover a mower and a bike without either chain reaching the door.
Check it annually.Retorque the fixings, look for rust in the chain links and around the anchor, and check the resin has not been undermined by water. Five minutes each spring.

Tips

Photograph the serial numbers and register them on a national property register. Anchoring stops the theft; registration is what recovers the item afterwards.
Check the insurance wording — many policies require a specified anchor and lock rating before they will pay for a bike stolen from an outbuilding.
A cheap chain defeats an expensive anchor. Spend proportionally, and never use a cable lock in an outbuilding.

Common mistakes

Bolting an anchor to a timber shed floor — The whole assembly can be levered up with the board it is bolted to. The anchor has to reach concrete or masonry to mean anything.
Leaving the chain slack on the ground — A chain lying on a hard floor gives something to work against. Keeping it taut and clear of the ground removes that entirely.

If it doesn't work

Drill breaks through into a void

Cause: Thin slab, or a suspended floor rather than a solid one — Fix: Stop and reassess. Use a wall anchor into solid masonry instead, or a longer resin-anchored stud into a thicker section of slab.

Resin fixing pulls out under load

Cause: Dust left in the hole, or loaded before it cured — Fix: Redrill oversize, clean meticulously with brush and blow pump, refill and respect the full cure time — which is longer in cold weather.

Anchor rusting after a winter

Cause: Cheap plating, or standing water at floor level — Fix: Choose a stainless or galvanised anchor for an unheated outbuilding, and if water pools there, fit a wall anchor instead of a ground one.

Questions people ask

Ground anchor or wall anchor?

Whichever reaches the better substrate. A wall anchor into solid brick is generally stronger than a ground anchor into a thin or crumbling slab, and it keeps the chain off the floor, which is an advantage in itself.

Can I fit one in a rented garage?

It needs permission, because it means drilling the structure. Many landlords agree, since it improves the property. A heavy portable anchor plate is the compromise where drilling is refused, though it is markedly weaker.

Will an anchor damage the concrete?

Not if you drill the specified size and keep sensible edge distances — usually at least 100mm from any edge. Drilling too close to an edge is what cracks a slab.