nails are a good idea. you could fashion home made spike strips with a bit of scrap wood and some nails and screws. if one of the little bastards runs over it and blows a bike tire they’ll get the message pretty quick. trust me I’m a teen and i know how we work. and if they come up to your door to complain about a flat from your spike strip just tell them that they’re trespassing and shouldn’t be in your yard in the first place. teens are crafty not smart so the odds of them being able to come up with a solution to your spike strips is little. and when you need to mow just put the strips aside until your done

Try planting bushes and being VERY liberal with staking them, to the point where it almost makes a fence.

Another option is to make a path along one side of your property that is inviting to bikes. That way they kids will go on the path instead of randomly across the yard. At least then it won’t wreck the lawn.

Really there’s nothing you can do to stop kids from going across the lawn – even a fence is only a deterrent, and if you do anything TOO aggressive, they will take it out on your house/lawn, which you definitely don’t want.

Contact the HOA and ask them what you *can* do to stop the traffic. Complain that it’s ruining your yard and they shouldn’t be trespassing on your property in the first place. HOA members are usually pretty much jerks when it comes to someone breaking the HOA rules. I’m sure they would be all over this (those little old ladies love nothing more than enforcing stupid rules on people, especially kids).

And, don’t put down anything like a nail strip. If one of the kids gets hurt, you will be liable.