Reddit reviews Kryptonite KryptoFlex Looped Bike Security Cable, 4' (10mm)

The cables are cheap! Doesn't need to be a full on lock. The u-lock should connect your back wheel, frame, and the thing you're locking to. The cable is just to connect your front tire if it has a quick release. Something as simple as this should work (and not break the bank!).

A visualization, just in case.

Alternatively you can get a cable and run it through the seat and your bike lock

http://www.amazon.com/Kryptonite-720018210818-Kryptoflex-Looped-Cable/dp/B000NORUJW/

The only downside to the Sheldon Brown method is if people mimic the way he has his bike locked up in the image on his page - u-locking the bike to a rack through the rear wheel and nothing else.

Brown actually recommends using the u-lock to lock the rear wheel and seat tube to a sturdy object and using a cable lock to lock the front wheel to the frame; this uses the u-lock to protect the two most expensive parts of your bike - the frame and the rear wheel.

I personally use an OnGuard Bulldog Mini U-Lock and a Kryptonite Kryptoflex braided cable lock. The mini u lock leaves no space for a would-be thief to put a jack in lock and pop it open.

It should be noted, however, that there are professional thieves who are brazen enough to actually use an angle grinder, acetylene torch, or some other power tool to defeat a u-lock. There is not a lock or locking method invented that can stop a determined professional thief. You have to decide the acceptable risk you're willing to take when leaving your bike in a public space.

It was a quick in-n-out. I usually have a cable lock with me for the front wheel, but forgot to grab it. Also, these BLB King hubs use 8mm allen bolts opposed to traditional wheel nuts.

Water bottle cage: https://www.amazon.com/Elite-Custom-Race-Bottle-Cage/dp/B01278EEF4

Water bottle: https://www.amazon.com/CamelBak-Podium-Water-Bottle-Carbon/dp/B015DJGYA2

Lock: https://www.amazon.com/dp/B005YPK8R6/ref=cm_sw_r_cp_apap_8CwnXlbqFlmyY

Optional cable: https://www.amazon.com/dp/B000NORUJW/ref=cm_sw_r_cp_apa_JX1CAb8VGDAVH

Helmet: there's a lot out there, you really don't need to spend a ton, but don't buy used.

Just because this is what I use doesn't mean you have to. Look around and buy what you think is best for you

Instead of trying to get a U-lock around a crappy bike rack, pick up one of these double loop cables and keep it in your bag. It's just a short cable with a loop on each end. Put the U-lock around the seat tube and through the rear wheel (making the bike unrideable), then loop the cable around the rack and lock it to the U-lock. This technique also allows you to lock up to trees, lampposts, etc.

Edit: words

I use this heavy ass lock. A hacksaw can still cut through it, but it takes more time.

I also use a cable to secure my quick-release front wheel.

There's no sure way to secure your bike, all you can do is use good locking stratagy. Lock it to something solid in a well lit place where people are more likely to notice a theif holding a saw or bolt cutters.

Use the U lock to secure a rigid part of the bike to something. The less airspace, the better (to prevent leverage attacks.) If you want to secure your wheels or other parts of your bike, get a cable to go with your lock, something like this. In a pinch you can even use the cable with your lock to attach to something really large like a tree trunk (though it won't be as secure obviously.)

ABUS 540 U-Lock supplemented with a Kryptonite cable
(A) https://www.amazon.com/dp/B00HN47G1M/ref=cm_sw_r_cp_apa_i_w9thDbFAY40XT
(B) https://www.amazon.com/dp/B000NORUJW/ref=cm_sw_r_cp_apa_i_f.thDbBGHKB6P