Ulock - very comfortable and reliable bike protection, only thick and heavy (4-6 kg) chains are better than ulocks.
Ulocks are very convenient devices to use... but how carry them? For 10 years I have been trying to invent, make and test the perfect Ulock bike mount. I bought and ... threw away most of the available on the market (Kryptonite, ABUS, aliexpress, etc.). They all have the same disadvantages: THEY DAMAGE THE FRAME, they don't hold Ulock and they are terribly hard to handle. I specifically tested Kryptonite solutions which are one of the worse of all, they clatter, scribe the varnish and simply crush any carbon element. Of course, in case of those heavy Ulocks (2-3kg). After many years I decided to make a prototype. The inspiration were pendants for the well-known and once popular Maglite offensive-defensive flashlights. The idea was a simple loop of wire or sheet of metal attached to a belt. There was no time for shaping the metal, so I took a piece of Kevlar rope (Dyneema diameter 4 mm) and tied it to the rack. It was supposed to be a prototype, it cost about PLN 2 (USD 0.50) and I've been driving with it for 12 months now. Kevlar rope is a tough beast, it doesn't stretch and doesn't rub. The curvature of the rack and the geometry of the Ulock cause the Ulock to be pressed against the rack. Nothing crawls, nothing clatters on bumps. On mega-large curbs it will jump up, but it will quickly return to its place.
A similar solution can be purchased, they are made of leather or textile straps / belts. For example, the one in the picture (U-Lock Holster or BLB Lock Holder). These are very nice solutions but ... unfortunately they have three disadvantages: 1. You need to know the exact width of your U-lock 2. Under the influence of time/rain/frost it works less and less reliable, it strats tapping or wobbling ulock while driving. 3. The mounted mounting blocks the possibility of mounting panniers, lamps, luggage.
The overstretched strap starts to fit badly and it's hard mount an ulock in and even harder to take it out - it gets stuck. In my opinion, the belt is also difficult to attach to the bike, you have to combine with washers, Velcro. For me, it was an insurmountable problem, although ... I must admit that I already bought the belts and almost sat down to the sewing machine. The biggest problem for me, however, was taking up space, which I sometimes use to attach panniers or luggage.
Although the strap mount is one of the best you can buy..
The solution turned out to be a piece of string... a simple piece of string (line, rope, wire), unevenly cut, tied "only for a moment". It was supposed to be a prototype solution before bending a piece of wire, because originally I wanted to make a metal wire hanger. A piece of string (dyneema lines, diameter 4 mm) tied more or less to the size of the Ulock worked out great. It is light, flexible and does not interfere with anything. Ulock is stable and secure. The line must be tied tightly and securely, because it is gets large dynamic loads.
How to tie a rope? English sailors have a saying "tie a knot or tie a lot" meaning tie a knot (if you know how) or tie a lot (many times if you don't). It works, if you know how to tie a knot do it, if you can't tie it, tangle it, wrap it a lot, many times.
You can see how it looks below:
It even works with kids bikes. We have Woom bikes, quite expensive, worth protecting. So in the Woom 3 you can mount a woom rack, it come with a rubber band. It just took 3 loops to fix the band do the Kryptonite U-lock fits perfecly. No wobbling, no scattering, zero soumd. Silmple and great solution. Super easy to take out ulock super easy to put it in. Even for 4 year old it no problem to mount a fully grown u-lock. This would not be possible with officak Kryptonite or ABUS ulocks mounts.