If you have a small frame, or bikepacking luggage taking up your main triangle, the Guee Mag One is a clever combined bottle and cage that pivots out sideways thanks to its nifty magnetic attachment.
Instead of a cage, the system has a mount that incorporates neodymium-iron-boron (NIB) magnets. Since their invention in 1982 by General Motors and Sumitomo Special Metals, NIB magnets have become ubiquitous in applications that require high-power permanent magnets. They're the reason earbud headphones work, they allow modern hub dynamos to produce useful amounts of power and without them ebike motors would be much bigger and heavier.
The Guee Mag One has four NIB magnets, two in the mount and two in the piece that fits into a moulded recess in the bottle. You attach the mount to your bike with the included pair of M5 dome-head 3mm Allen key screws and you're away. Get the bottle reasonably close to the mount, and the magnets do the rest. It's not the same as putting a regular bottle into its cage, but it's just as easy, and rapidly becomes second nature. Lightly sprung plastic latches on the bottle help to keep it in place.
It stayed put while I bounced over some of the roughest local drove roads. Cambridgeshire's fens are intercut with knackered old concrete-surfaced byways, often with steps or gaps between the slabs, or chunks of the surface simply missing. Some of them were tarmacced over sometime in the late Paleolithic and that tarmac is now full of holes. If a bottle doesn't jettison over this stuff it'll stay put anywhere.
To remove the bottle, you twist it clockwise. That means it doesn't matter if there's something in the way of the upward path of a traditional bottle. The Mag One is therefore perfect for bikes with restricted space in the frame, whether it's because they're very small or because there's a frame bag under the top tube getting in the way.
The bottle comes out to the right-hand side of the bike if you've mounted it on the down tube. If you're left-handed, that might be a problem. I certainly found it awkward to remove the bottle with my left hand, but I'm very right-handed. Left-handed folks who are used to compensating for a right-handed world might have less difficulty. With the Mag One on the seat tube, it comes out to the left, which is definitely awkward for me. It'd be nice if Guee made versions that released clockwise and anti-clockwise. That way you could get one of each and fit them to the down tube and seat tube to match your dominant hand.
The bottle magnets sit in a plastic moulding that's recessed into the bottle, and can be removed if you want to put your bottle through the dishwasher. Make sure you put it back in the right way up, following the arrows, or the magnets will repel those in the mount and it won't work. You lose a little capacity because the mounting is moulded into the bottle. A standard water bottle like a Camelbak Podium can hold just over its claimed capacity of 710ml. The nominally 600ml Guee bottle will take 645ml if you fill it right to be brim. Most of the Podium's extra capacity comes from it being a few millimetres fatter than the Guee bottle.
Judged as a bottle, the Mag One does the job just fine. Its screw-on lid fits snugly and its silicone pull-valve dumps plenty of water into your mouth. It's quite stiff though, requiring a decent tug to get it open. The main body is made from food grade polypropylene and has no discernible effect on the taste of the contents. The polypro formulation here is a bit stiffer than most, but that's a very minor niggle.
Guee isn't the first company to come up with a magnetic bottle mount. Vincero Design's Stratus system has been around for a while, and works well. The Stratus design doesn't provide the space saving you get from the Mag One, though its low-profile mount looks tidier when you don't have a bottle on the bike. Swings, roundabouts.
At £45 the Guee Mag One is expensive; over three times the price of a typical good quality bottle and cage. However, you can get the same thing under other labels for about £30 (see below). That's a reasonable premium for the space saving it offers and the extra parts and mouldings necessary to get there, but £45 is a bit silly.
I think Guee has missed a trick in making the mount work only with a proprietary bottle. The conventional bottle and cage is one of very few remaining universal standards on bikes, and a small player isn't going to change that, however clever its alternative. If the magnets and latches from the Guee bottle could be fitted to a conventional bottle, that would open up the market for the Mag One. I'm imagining something like a pair of hose clips (but much tidier) to attach the bottle part of the system. Then you could use your favourite bottle, or a pair of Zefal's one-litre Magnum bottles if you want to carry lots of water, or you could carry anything else that's roughly the diameter of a water bottle.
This bottle and cage pairing here is available under at least three brands. The Restrap Mag Bottle is exactly the same thing and so is the Fidlock Bottle Twist. The Guee bottle is actually marked Fidlock on the bottom. Fidlock is a German company that makes buckles and fasteners like the magnetic buckle on some Abus helmets, so it seems likely it originated the design.
Whichever version you get, the Guee Mag One is a well-executed answer to the problem of cramming water bottles into tight spaces. It fits to your bike just like any other bottle cage and it stays put on rough roads better than some cages I've used.
Clever answer to the question "How do I fit a water bottle on a small frame or under a frame bag?"
road.cc test report
Make and model: Guee Mag One Cage Free Bottle Holder
Size tested: Volume: 600 ml
Tell us what the product is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?
Cage free bottle system, simple & elegant way to attach bottle. Perfect solution for small or unique-shaped frames! BPA free, bottle replaceable.
Tell us some more about the technical aspects of the product?
A perfect solution to the cramped spaces of small or uniquely-shaped frames.
A simple and elegant way to attach bottles effortlessly to the frame.
Restores the beauty of your frame when bottles are not mounted.
Engineered with neodymium magnets for secured mechanical locking. No more dropped or ejected bottles, no matter how rough the road or how little fluids you have left.
Toxic-free cap and large sized valve gives an easy liquid flow while using.
100% BPA free bottle, convenient size.
Volume: 600 ml
Bottle: Food grade PP
Bracket: Plastic & neodymium magnets
Tidy mouldings, very good fit and finish.
Does what it's supposed to do very, very well indeed.
About the same as a typical standard bottle and cage.
There's no getting around the fact that £45 is a lot of money for a bottle and cage, and the Restrap and Fidlock branded versions of the same thing are substantially cheaper.
Tell us how the product performed overall when used for its designed purpose
Very well; very straightforward and easy to use.
Tell us what you particularly liked about the product
The satisfying click as the magnets pull it into place.
Tell us what you particularly disliked about the product
The pull-valve is a bit stiff. It's right-hand-use-only when mounted on the down tube.
Did you enjoy using the product? Yes
Would you consider buying the product? No, but only because I don't have an application for it.
Would you recommend the product to a friend? Yes, if they had a very small frame or needed a bottle that fitted with a frame bag.
Use this box to explain your score
The Guee Mag One works very well, but it's expensive, which pulls its score down.
About the tester
I usually ride: Scapin Style My best bike is:
I've been riding for: Over 20 years I ride: Most days I would class myself as: Expert
I regularly do the following types of riding: commuting, touring, club rides, general fitness riding, mountain biking
Our official grumpy Northerner, John has been riding bikes for over 30 years since discovering as an uncoordinated teen that a sport could be fun if it didn't require you to catch a ball or get in the way of a hulking prop forward.
Road touring was followed by mountain biking and a career racing in the mud that was as brief as it was unsuccessful.
Somewhere along the line came the discovery that he could string a few words together, followed by the even more remarkable discovery that people were mug enough to pay for this rather than expecting him to do an honest day's work. He's pretty certain he's worked for even more bike publications than Mat Brett.
The inevitable 30-something MAMIL transition saw him shift to skinny tyres and these days he lives in Cambridge where the lack of hills is more than made up for by the headwinds.