How to anchor a chain to asphalt (to prevent scooter theft)

Tool Talk
#1

Hi all! This is not strictly about tools, but it’s way outside my field.

I just bought an electric scooter, and I should get delivery in a few months. I don’t want it to get stolen, naturally, but there’s nothing to lock it to in the parking lot. (All fences are wood, and there is no handy concrete wall.)

So Kryptonite makes a purpose designed anchor point ($75) that bolts to concrete floors. It has a 1/2" hardened steel shackle that sticks up from the ground, and also folds down, which is handy.

But it is supposed to attach to concrete (with included concrete anchors.) So:

  1. How do I anchor the thing to asphalt? Is there some kind of anchor that uses epoxy or maybe screw threads that work in loose aggregate? I would imagine it should go pretty deep, say a foot at least.

  2. Is there an alternative to this Kryptonite doodad I should consider? How would you create a secure spot to chain a scooter or motorcycle to?

I’d prefer not to dig a hole and pour in concrete, but I’ll consider it. (How do I even dig a hole through the aggregate?) Thanks!

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#2

When I was in college I had a similar concern with my motorcycle being stolen from my apartment parking lot. I ended up making a device very similar to the Kryptonite thing you posted. I purchased a big forged Eye Bolt like these:

…cut the threaded end off, and welded it to a steel plate with 4 holes in it. I drilled holes in the concrete and used normal concrete anchor bolts to secure it. If I had to do it again I’d just buy one of these instead:

I don’t believe that wedge anchors or threads will hold in asphalt. However, epoxy should. I’d bet you could epoxy a big eye bolt straight into a hole drilled in the asphalt. There is even special “anchoring epoxy” made for that kind of task.

2 Likes
#3

Brilliant, MechaMan, thank you!

The pintle ring looks like a better plan than the eyetbolt, because I could see an eyebolt being yanked around and maybe cracking the asphalt. Also, the pintle ring can be secured with ordinary bolts, and it’s easier to find 12" ordinary bolts than 12" eyebolts, especially in stainless steel.

The anchoring epoxy looks perfect.

But then the question is what kind of bolt do I use to hold down the pintle ring (or the Kryptonite doodad.) I like carriage bolts better than any of the various security bolts, because you can get really long ones (18") in stainless steel, and the smooth head gives no purchase for thieves. But the problem is the square collar behind the head, which won’t fit into the round holes in the pintle ring. There are carriage bolts with knurled collar, but apparently they aren’t available long, or hot dip galvanized or in stainless steel (at least not at McMaster-Carr.) Neither are the various tamper-resistant screws.

Any suggestions on what bolts I should use? Long (around 12" say), rust-resistant, not easy to turn with common tools, and preferrably cheap? Maybe I should grind the corners off ordinary stainless steel hex-head bolts? Or grind off the square corners on the collars of stainless steel carriage bolts? That seems harder. Of course, if a hot dipped galvanized option is out there that doesn’t need grinding, that would be best.

#4

So some digging finds BoltHold asphalt anchors.

https://www.asphaltanchors.com/

The anchor is a a steel sleeve, threaded on the inside for standard bolts, and threaded on the outside with a very coarse, wide thread that doesn’t actually thread onto anything. All it does is provide purchase for the epoxy or grout you use to fix the sleeve in a larger hole you drill into the asphalt. It has some clever features, like a washer welded around the top so it doesn’t drop too far into the hole, that also helps contain the grout in the hole.

The SP58-58 anchor, that takes a 5/8" bolt (which the Kryptonite thing uses), needs an 1 1/2" wide hole (!) about 9 inches deep. And the anchors cost $180 (!) for six for the stainless steel, a little less for the zinc-plated steel (and I’d only need three). Plus you need their special expanding grout or epoxy.

But the advantage is that the Kryptonite thing (or the pintle ring that MechaMan suggested) can be removed, and the anchors will be flush with the surface surface. And each anchor has a claimed 5,000 lb. pull force rating.

That seems like overkill, but the Kryptonite thing comes with 5/8" bolts (hex drive) with ball bearings sized to fit in the hole, to render them tamper-proof. Smaller bolts would likely be strong enough, but the Kryptonite thing might slide around a little, which won’t feel secure. And I’d have to source the right bolts, ball bearings, etc. So using the BoltHold anchors that take 5/8" bolts seems easiest.

Unless you have other ideas? :smiley:

#5

Home Depot and Zoro sell Vestil asphalt anchors. I don’t remember us ever using them - but here’s a link:

I do remember us having a a job to install removeable signage in a commercial parking lot. We bid and did the job by installing small concrete pads with embedded anchor points.

Here a a few other links that may be useful:

#6

For my installation I used wedge anchors that had male threads at the top. I used ordinary nuts and washers, but I hammered over the end of the threads that was protruding up from the nut so it wasn’t so simple as as just undoing the nuts. I suppose it could have been possible for someone to use a big enough wrench and shear off the anchors but you can drive yourself nuts trying to think of every possible weakness. Besides which, the lock or the cable/chain is likely the biggest security risk.

If I was trying to do this and keep the budget low I’d use ordinary bolts. Drill holes slightly over the nominal bolt diameter. Blow or vacuum the dust out of the hole, degrease the threads on the bolt so the epoxy sticks well, slather the threads with epoxy, get epoxy in the hole too, tap the bolts in with a hammer. If you were concerned about corrosion you could use stainless bolts. Carriage bolts would work, just grind or file off the square corners under the head. This solution is probably not as strong as using proper asphalt anchors but they seem very costly, and I think so long as you’re using some large bolts the epoxy method will hold well. There is an awful lot of surface area for the epoxy to grip on the bolt’s threads and also flowing into the gaps in the asphalt.

Figure out how thick the asphalt is if you can. It might be two inches, it might be twelve inches. If it’s super thin then alternate plans are in order.

#7

I suppose if you could drill completely through the asphalt slab into the subsoil - you might be able to remove (compressed air, water jet or vacuum) just enough of the subsoil to be able to force in long toggle bolts (set in your anchor plate) and let them open their wings. Then backfill the oversized holes with epoxy and tighten the bolts down. Then the only task left would be to adequately damage the bolt heads to prevent easy removal.

#8

@fred,

Thanks for the links! I found the Vestil anchors on the HD site, but neither they nor the Zoro site provide any information on the things other than cost.

Those asphalt bolts look interesting, but the material is just listed as “steel”, and I’d want some corrosion resistance. (Grainger’s provides no information either.)

Using long toggle bolts (or putting the anchors on long bolts) seems like a good idea, because I can put the anchor at the very end of a long bolt. But I’d wonder about excavating enough space to let the wings expand. The aggregate is just sitting on compacted soil, right? Wouldn’t the aggregate fall into whatever cavity I made in the soil?

#9

@MechaMan,

Thanks, that sounds like the best idea. Stainless steel carriage bolts, maybe 10" long, with the square section ground off, set in oversize holes with epoxy.

I think I’d use the special grout from BoltHold instead of epoxy though. The stuff expands as it hardens, so it would seep somewhat into the aggregate, so the actual anchor becomes a mass of aggregate and grout. I guess I could even try to force grout into the aggregate using air pressure or a piston or something. At 10" long, the bolts may enter the subsoil, but I don’t see that as a problem.

I could also grind some shallow notches in the bolts to give the grout a better grip.

Another idea is to use threaded rod and some kind of security nuts, maybe those shear nuts, at top. That would let me remove the pintle ring if needed.

Prepping the holes will be a pain. I’ll have to at least blow them out, maybe with canned air and some kind of long thin tube. That BoltHold website advises brushing out the hole with a bottle brush.

By the way, I’ve read things like wedge anchors won’t work in asphalt. Asphalt flows under continuous loads, so eventually the wedges pressing outward in the hole would widen the hole and pull out.

Yes, the chain and lock are weak points, but I’m looking at hardened chain, 1/2" dia or more, and a hardened lock. Actually I’d imagine the pintle ring is the weakest spot, because it’s not hardened and a grinder could deal with that quickly. Am I wrong?

#10

Hard steel is extremely difficult to cut with a saw but it doesn’t really matter to a grinder. Whatever is thinnest is the fastest to cut, probably either the chain or the shackle on the lock.

Be careful with your lock selection too, many well known locks are honestly terrible when it comes to security. Here’s a great irony from the famous Master Lock. They make a lot of padlocks up to and including the No. 19, which is honestly enormous. The steel bodies are quite tough but the core inside is terrible for security. They are only 4 pins and the mechanical tolerances are very sloppy, even an amateur can easily pick them. Meanwhile they also make plastic bodied locks for industrial lockout-tagout safety procedures. They’re not really meant for security, yet they contain 6-pin cores built to tighter tolerances, and they include anti-bump pins which make them a lot more difficult to pick. So for some reason Master decided that their locks actually meant for security get lousy cores while the ones meant for a symbolic safety procedure get ones that are somewhat advanced. Makes no sense.

#11

@MechaMan

That’s good to know!

I’m looking at this lock:

With the right chain and shackle, nothing in the entire setup will be less than 1/2" of hardened steel.

#12

That’s a good lock, very strong and the disc detainer mechanism instead of a normal pin tumbler lock makes it essentially impossible to pick.

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#13

Assuming you have access to a welder, you could just weld a bit of all-thread (you can hit with POR15 or similar for corrosion after) or HDG bolt to a long bit of rebar. Pull-out strength in soil for rough “nails” of say 2-3 ft are crazy (similar to soil-nailing for retaining walls or friction piles), especially when that soil has been compacted. Certainly strong enough to the point where any determined thief would be bringing the tools to overcome whatever obstacles you create and/or isn’t concerned with destroying the asphalt. Probably much cheaper and more readily accessible than dedicated asphalt anchors.

#14

@indianajonesy

Thanks for the suggestion. I don’t have access to a welder, nor do I know how to use one!

But that’s interesting. I guess you’d drive the rebar in with a sledge hammer?

One issue is that I expect people would try to pull the shackle sideways, so I’d want it to be secured close to the surface. Otherwise they could widen the hole in the soft asphalt. They wouldn’t be able to pull it OUT, but they could still mess with it.

#15

Gotcha…I suppose you could just use a really long HDG bolt or maybe stainless all-thread, but not sure how accessible (or cheap) they would really end up being.

For the rebar, yeah…just a sledgehammer works pretty well. It’s a great way to anchor wood landscape walls/raised beds as well.

Trust me from experience that these things are terrible to try and work out of the ground. It takes a good bit of effort (usually a combination of a sledgehammer and directed high pressure water) to widen the hole enough even without asphalt/soil compaction involved and with a decent amount of tail on the rebar to use as a lever. In this application, there would be little to no available leverage with which to widen the hole, especially as you would (I assume) have two of these rods, providing a decent amount of shear resistance. I guess if they hooked a chain to a vehicle and the shackle, you’d have an issue. If they’re that desperate, though, they can damage it no matter what you use. Nothing is really going to hold up to that level of attack (short of a proper bollard or concrete footing). At that point it’s either targeted malice or a more professional thief. There’s not much you can do to prevent either other than provide a level of difficulty which disuades them from your scooter as a target.

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#16

You could drive the rebar with a sledge, though if my experience driving electrical ground rods is anything to go by it’s pretty miserable work. I imagine rebar would be worse because it’s ribbed. If you have access to an air hammer like auto shops use or an electric rotary hammer one can get “ground rod driver” tools for them. These make it much easier to drive. I think I’ve even seen these for rent at Home Depot.

and indianajonesy is right about them being difficult to remove. I tried to pull a ground rod I had to move when my business got a new CNC machine and managed to break a 2-ton rated cable grab trying to pull it with a forklift.

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#17

reading this a few times I have to say how much is the scooter and is it worth all this effort vs some insurance claim. which I assume here you would have insurance of some form.

and I’m envisioning something vespa like as the device only electric. maybe post up what the scooter is as there may be other options. Like wheel removal or a power disconnect where you take the switch with you. etc.

Then sure they might toss the thing in a truck but you’d have rendered is nearly useless. maybe even consider a GPS tag.

Otherwise of the options I like this rebar idea or maybe even use all thread if you don’t want to weld… take a bar of all thread like I don’t know 3/4 - grind a slight point - cut to say 18 inch or so - getting more of that into the ground. Might even be worth starting the hole with a drill auger (I do this with rebar and landscape timbers)

then you could put nuts on the top and say epoxy them on. if you’re that worried about it.

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#18

@Napalm

Yeah, good to keep that in mind. The scooter is about $4,000, but fairly light. Two people can toss it in a truck easily. So I think things like brake locks or steering locks aren’t enough. It needs to be secured to something.

But I’ll be removing the battery each night to charge. It costs about $1,500 by itself, and the scooter is not operable without it, but I don’t trust thieves to know that, and I’d still be out $4,000 (though I might make a sign saying “No battery” to put on the rain cover.)

I like the rebar option, though I’ll likely use stainless threaded rod (why do things halfway?) But from what you and others say, the rod will hold well to compacted earth, but I doubt it’ll hold well to the crushed aggregate that’s under the asphalt. So for those top few inches, I’ll use the grout recommended for those asphalt anchors I mentioned. The grout is cheap.

So with shackle, lock, chain, stainless threaded rod, grout, and shear nuts, I’m looking at about $300. That seems reasonable to protect a very common theft target that costs $4,000, right?

#19

My only concern w/ threaded rod vs. rebar is the ability to handle deformation. Rebar is meant to handle the loading during install, not so sure stainless will hold up as well (plus obviously the minor diameter of all-thread is much thinner than the nominal dimension, so you’d want to size up). I think a better option (if you can find them or are willing to special order) would be to go with a 1/2" x 24" (or longer) HDG bolt and cut off the head (maybe even point it a bit to aid driving). Downside is the smooth shaft, but I don’t know that that would make a ton of difference honestly. Otherwise, I would definitely consider predrilling to close to the minor diameter so as to make it less likely to deform under that loading.

#20

@indianajonesy

Yep.

I think I’m abandoning the idea of driving some kind of rods into the compacted earth under the aggregate. I don’t know how long it will take, and I’d have to rent an SDS, and it could be a noisy, lengthy job.

So I’m thinking I’ll use threaded rod in oversize holes with anchoring grout. The Kryptonite shackle comes with a 5/8" concrete bit. I could use that it to drill through the aggregate and maybe a bit into the compacted earth underneath. fill with grout, wait for the grout to flow a little into the aggregate, then drop in 1/2" threaded rod. Should be quicker.That will also give the rods have a little wiggle room, for better alignment with the shackle. Fasten the shackle with with shear nuts, which are not expensive, then cut off the excess rod.

If it turns out the aggregate is not very thick, I might still drive the rods some inches into the compacted earth underneath. But either way, grout in aggregate would the primary anchor.