U-lock holsters
There are an infinite number of ways to carry a U-lock on your bike frame, or on your person. People are devising new ways all the time, it feels like. They feel like something you ought to be optimizing because they are heavy, and just large enough to be a bit unwieldy. They come in several different sizes, and something designed to hold one style of U-lock may not hold any others securely.
When I park my bike, it's generally only in two or three well-surveilled or physically locked locations, so I generally travel with only a single U-lock. I use the Kryptonite Evolution, which weighs 3.5 pounds and costs around $100 - $120 USD. If you live in the US and are serious about your bike not being stolen, this is probably the cheapest U-lock you should consider buying. It's absolutely not going to stop someone from stealing your bike - no U-lock will - but it will make your bike marginally harder to steal than many other bikes on the same rack, which is pretty much all that matters.
On my main bike, I use a plastic frame bracket which came with the lock to hold it inside my center triangle. But on my minivelo, which I posted about last week, I don't have a second plastic clip. Buying one would cost around 16-20 USD, but that only handles one frame. I'd have to buy one for every bike that I own. What a pain!
So instead of getting two brackets, I started looking at other U-lock holsters. I ended up choosing something which costs about exactly the same as a plastic bracket: a belt holster that can come with me no matter what bike I am using. It is sized precisely to hold the standard-sized Kryptonite Evolution lock. When I slide the lock inside it, the pressure of the lock and the holster strap against my body keeps it from sliding downwards.
One alternate type of belt holster I see - and frankly, I see it more frequently than I see something like my belt strap - is a hip pack/fanny pack/bum bag type bag with a holster in the back of it. The bag and the belt strap together form the holster slot that the lock slides into, and the size of that gap plus the tension of the belt together hold the lock in place. This is a very bike messenger-type bag to have - it's a great way to hold a lot of little bits and bobs you might need for actually working on a bicycle, and to keep them accessible to your hand while you are cycling.
There is something strange about holding a U-lock on your body as opposed to your bike frame - it makes everything feel lighter! These holsters keep the lock close to your center mass, which makes it very easy for you to simply forget that it is there. Taking 3.5 pounds off your frame makes it easier to move the bike with your body or your hands, both while cycling and while rolling it around in buildings or up staircases. Lots of things do feel easier this way, even though I and the bike together weigh precisely the same.
The only limitation is that because it requires a belt, I can't wear this holster and wear lycra-style bike shorts at the same time. But I use this holster pretty much only when I am on the minivelo or the fixed gear, and I pretty much only use those bikes in street clothes, so I can always wear a belt when I'm on those bikes.
I wrote this post because I was pretty worried about using the holster when I first picked it up in early 2024. I was real worried that the lock would fall off me and hurt me on the way down to the ground. But a year later, it's been better and more convenient than I expected. If you have multiple bikes and want to carry one U-lock around with you in a low-stress way, I can't recommend one of these enough. You just gotta like belts!!