Mason 180

Sturdy, very light weight. Perfect size for my hybrid bike in a large city.

I bought the Mason 180 as the main lock for my Trek Dual Sport bike, and on arrival was blown away by the quality of this thing. The key turns smoothly, the lock opens and shuts nicely and it isn’t near as heavy as other locks of the type. I’ve seen complaints about the zip ties that come with the mount for this but I found they worked really well (even after my dog chewed halfway through one, leaving it held on by only 1.5.

Definitely recommend the mount too, but mounting was my only disappointment with this thing. I have a decently large frame bike and there is nowhere on my inner frame I can mount this while also having a water bottle mounted. I found most of the rest of the recommended mounting angles awkward or in the way of body motion while biking, fortunately my bike has a back rack mounted on it and I was able to mount the lock to that instead.

Overall, great lock at a great price. Just check the measurements against your fame before buying for mounting reference!

Mason 140/180 locks are a relative joy to use. The 140 has been just enough in all situations so far with my steel-framed road bike. Rigid & grippy, no wobble on Seatylock mount, and a significant bit lighter to make these next level products to own. I do wish that it had been made more clear that (3) keys are included, as I had purchased as many spares again with the lock order and at a very high cost. Gotta make some time to follow up on that ~ No time for photos of this type either, but you get the picture -

Very nice lock, You can feel the quality. Just the right size, fits back wheel through the triangle to a post every time.

Somebody can always bust your lock, but they’ll break a sweat to get to your bike

Great size for getting the frame and wheel without much extra room

I'm really impressed with the design and light weight of this lock.

Seatylock Mason U-locks have all earned the highest Sold Secure Diamond rating along with only a few of the top models from bigger brands that are much heavier and way more expensive. Mason model numbers refer to the inside length in mm. The Mason 140 & 180 are 85 mm wide inside while the 220 & 300 are 115 mm wide.
I chose the 180 because it fit within my frame along with a bottle cage and tire pump with enough room to easily mount and remove it from the bracket attached to the seat tube.
Considered a compact U-lock, the Mason 180 is just big enough to attach one wheel and part of the frame to a post with no room for a thief to get in with large wrecking tools. Otherwise it will fit around most posts and just one tube, but you should also carry a good foldable lock, chain or cable (at least 10 mm thick) if suitable posts are not available and also to secure removable parts like wheels and the saddle.
The shackle is hardened steel with a triangular profile for the 140 & 180 and pentagonal for the 220 & 300 and is thick enough to stop a bolt cutter and really slow down an angle grinder. The locking bar is steel, reinforced where the shackle is secured at both ends by a spring-loaded mechanism that prevents it from rattling and falling out when unlocked. The pick-resistant lock cylinder has a spring-loaded dust cover. The optional bracket can be mounted in various locations on the bicycle, attached by 2 plastic hose clamps. It has a push-button lock and is snug enough to resist vibration.
Shipping is free in the U.S. The shipping cost to me in Canada was mostly offset by the fact that no sales or import taxes were charged. You can contact the Seatylock site for prices and availability. Even if it may take a few weeks to get the Mason size you want, it will be well worth the wait.

I haven't used it yet (still haven't bought a new bycicle), but it looks and feels very strong and solid.
The delivery was super fast: less than 3 days to another continent - the fastest delivery I ever had!
And the price is really fair, too.
Great job, guys, definitely recommended!

Absolutely happy with the Mason 180 lock - soft covering saves bike from scratches, key can't fall out from the lock in open condition + secure, and the most awesome feature for me is that when both parts are connected but the lock is not in closed condition - the lock stays as one! It can be locked with one hand - thats super for me!
I like that 180 size allows to use lock with different parking stations, in case of narrow tubes on the station I can lock the frame and the back wheel which allows me not to use line if I have to leave my gravel for a short time.
Thanks to seatylock for good lock, I enjoy using it! Thanks for the answering my questions and fast shipping!
This is a great lock that you be proud to use!