How to mount a U-lock on a Brompton folding bicycle

I got a new Brompton folding bicycle recently, and after my recent unfortunately experience, security is foremost on my mind. Obviously the best solution is to carry the bike everywhere with you.  But that is not always practical or possible, which means you have to lock up your expensive wheels on the mean streets where bike thieves are just waiting to pounce. So a smart locking solution is required.

The problem: where to mount a lock on the tiny frame of a Brompton that won’t get in the way when folded and won’t interfere with your riding when unfolded?

Here’s some pics of my solution…

The Brompton is an amazing piece of bicycle engineering, a nearly perfect balance of economy in scale and efficiency in bicycling power.  Because its so space efficient, there is very little room for add-ons like water bottle holders, lights and baskets.  So I knew, whatever lock solution I found, it would have to be tiny.

I went to my local bike shop on Vanderbilt (the excellent Bicycle Station), where they sold me the OnGuard Bulldog Mini u-lock, which supposedly ensures your bike for up to
$1,200 if its stolen while locked.  Krytonite has an almost identical model, but Bicycle Station didn’t carry that one.  The Bulldog is quite small, but big enough for locking your frame to a street sign or fence.  Apparently small is not necessarily a bad thing, since a small lock can be harder for a thieve to wedge a cutting device in.

The Bulldog comes with a fairly standard lock mount and gives advice on where the optimal places to put the lock, none of which were really an option on the Brompton.  In fact the only spot I found that was a remote possibility was the handlebar post.

I tried attaching the mount a couple different ways before finding a mount point that works well both folded and unfolded. 

Here you see that with the lock on, the lock points straight ahead in front of the bike, totally out of the way of your legs.  You obviously can’t use this with any kind of front bag, but then you could just put the lock in the bag. Doh.

After a few tries, I couldn’t find any way to keep the lock on the bike while it is folded.  So every time I fold the bike, I have to take the lock off, which is kind of a pain.  Still it’s way better than having to carry around a heavy lock in my bag or have it rattling around on the handlebars when I ride.

Here you see the folded up Brompton with the mount clearly not in the way of anything.  When the handlebars are unfolded, you are shooting for around a 75 degree angle on the mount. 

Don’t attach the mount very tightly the first time and play around with folding and unfolding it before tightening the mount.  After tightening the mount, attach the lock and ride around a bit and make sure it doesn’t wobble at all.

I’ve ridden all around Manhattan and Brooklyn for a few days now and it works great. 

I hope this helps other Brompton owners to keep their bikes safe so what happened to me doesn’t happen to them.  Happy riding!