U-lock shackle brace on the cheap
 

So, my roommate had his bike stolen a few days ago (Gavin Durus) while he was in the gym on campus here in Fresno, CA. Any area within a 1-mile radius of Fresno State is like New York as far as bike theft - if it's worth taking, it won't be there very long. He also deserved it - leaving a $650 road bike (that he barely rides, so it's in good condition) locked with a chinsy $5 cable that's about as thick as a toothpick was stupid.

This got me thinking though (read: paranoid). Combined with the stories I've been hearing recently (about once a month since I moved into a house) about bikes being stolen from garages (where my bikes are kept) and I decided to beef up my security. I have all of my bikes locked with some standard (not very secure, to be honest) 450lb test chain (at least the links are welded) and protected shackle padlocks. It's not going to stop a determined thief, but it'll do.

For my commuter, however, I've only been using an OnGuard cable lock. Since everyone else around here uses a U-lock, I figured I was automatically more secure by using something different. Now, I feel like having two types of locks is the ideal standard for stopping a thief. I know the biggest weakness for U-locks, however, is prying/wedging (jacking) the shackle apart, and I also know that they sell expensive plates that prevent this. This got my friend and I thinking, and I came up with an idea.

One trip to OSH later and I had something: 1/2" thick, 4,500lb test galvanized chain. It can pass something about 17mm thick (most U-lock shackles are 15-16mm thick if you account for the plastic coating) through the entire link (end to end).

Here's a picture of my find...
http://bikeforums.net/attachment.php...hmentid=199689

This has two benefits:
1. It keeps the shackle from being spread apart by prying or jacking
2. It takes up space between the crossbar and whatever else is inside the shackle, making it harder to fit tools inside to try and pry.

The cost for this chain was $6.50 for a foot (7 links). Each one only requires 6 links though, so once you cut the 7-link section into two (you lose a link in the process) you pay $3.25 for each one (+tax).

It took a 200-lb employee several minutes (and 2 sets of bolt cutters) to cut this stuff for me, so I am feeling good about it. If my bike DOES get stolen, then maybe I can finally convince the wife to let me buy one of these:
http://fresno.craigslist.org/bik/2345379996.html
:D

Please, any opinions?

It took me a while to understand what u did lol.. but now it makes sense and is a pretty good idea :)

Damn good idea - gonna head to the marina supply and get one of my own (well, two, but you know what I mean.)

Nice idea.

You know about this, right?

http://www.youtube.com/watch?v=bphyY1pnjg8

Given enough equipment you can defeat any lock. If the thief brings an angle grinder and can use it without getting caught - they win.

I think the OP's idea is very clever, and will certainly make his bike a less attractive target than the one next to it!

Lacking a blacksmith, to forge and weld something.. not bad..

Thanks for the feedback guys! I'm glad you like the idea.

I'm not trying to be bulletproof here, just trying to be better than the bike on either side of me. I am fully aware that nothing will ever stop a determined thief, but the average thief won't be showing up with a car battery and power inverter or portable generator (in the middle of a college campus, no less) to run his angle grinder... so I'm not too concerned about that.

Plus, even if he grinds off my U-lock he'll still have to defeat my cable lock and for that, an angle grinder is not so handy (unless he brought his workbench/vice with him, too).

By the way - if you wanted to carry two (since most places will only sell you 1-ft increments), it would be handy when you lock up to something small - the additional one will act as more of a space filler and make it difficult to attempt to pry/wedge on the lock.

My next idea (if I couldn't find the right size chain) was to use flat-stock steel (let's say, 1-1/4" x 1/8" or 3/16"). Drill the right sized holes in the right places and round off the corners with a grinder (so they don't cut holes in your bag or rip your legs off when you walk by). I think the chain is more imposing and difficult to destroy, plus it takes up more space. The flat-stock would be (most likely) a lot less weight, though.

I had to cut two cable locks off a bike today. I timed it: With a set of Crescent brand diagonal cutters, the first cable took me one minute 7 seconds and I wasn't in a hurry. The second one took me 23 seconds, but my wrist was sore for about an hour.

Cable locks are useless. U-locks are much better, and your 'hack' makes them better yet!