I used to have a lock mounted to the license plate frame on the fender until I moved the plate to the lower shock bolt.

I now have the lock for the end of my Isogrips, though I think it's a bit ugly and the helmet taps the tank if there's wind. It also requires a special bracket that feeds through the D-rings then into the lock. Luckily there's a great little pocket to slide the bracket on the outside rear of my Plunderdogs. Almost like that's what it was for.

I'd really like to go back to the other lock if I could figure out a good clean place to mount it. It's a XL1200C with wide touring seat and no highway bar.

 

The down tubes on the Sportster rubber-mount frames are 1 3/8", causing issues with most helmet locks.
Google "thumb cuffs", or get a set of plain ol' hand cuffs.
I briefly used a very small cable and pad lock in the past, but I got tired of dealing with it. One advantage of the cable solution, if the cable is long enough, is the ability to run it through the sleeve of a leather jacket to secure the jacket. I think my Leatherman Skeletool has the ability to cut such a flimsy/small cable. Locks are for honest people, and kids are cruel.
The lock on the "What you did" thread is on a solid-mount frame. Different animal.

 

Depending on where I park, and how long I will be gone, I either hang my FF helmet, by the chin guard, over the right turn signal and run a cable through the rear wheel, over the rear fender, and through the opening. Or I put it on a mirror and use a dog choke/chain collar through the face opening and between the handlebar and cables/wires.

 

This is the lock I have. It came with different screws, depending on where you mount it.
http://www.harley-davidson.com/store...-lock-45732-86

I put it on 4 years ago, so I don't remember which length I used.

 

WTF
Double double
Post post

 

Thanks for the info...the reviews are rather mixed.

 

Here's how I hang my helmet, and you can see how the D rings are close enough to the mirror stem that I can lock it to the mirror.

 

That is convenient and accessible but can't see your mirror or how it is attached to it. Is the mirror sturdy enough to secure the helmet? Don't want my $600 investment to walk away especially since the helmet is in the open and easily seen.

 

Yeah I don't wear a $600 helmet haha. My mirrors are flipped, so you can see it inside the helmet. No, like I showed in a previous post I use a luggage lock that has a plastic sheathed cable. The cable is tiny, you could cut it with some side cutters easily. I only lock it to prevent some kid from grabbing it and running off. I don't think others would waste their time to steal my biltwell gringo. If I had a $600 helmet, it wouldn't be locked to my bike like this, that's for sure.

 

Thanks for the response. It is actually a $450 Shoei helmet and $150 Sena Bluetooth....regardless it is still a big investment to lose if you don't lock your helmet properly.