B'Twin 500ml Insulated Water Bottle

The B'Twin Insulated Water Bottle is a large bottle that sets itself apart from your usual water-carrier by being insulated and promising to keep your drink nice and cool in the summer and warm in winter.

At 264mm tall it's a bit bigger than a standard large water bottle, about 30mm lankier in all. Some of that height is taken up by the flappable cover on the top to save you drinking from a nipple that's been covered in road spray and maybe worse. This dome rattles and when flipped open for drinking can smack you in the face if you don't rotate the bottle so the hinge is at the bottom. Luckily the lid can be removed quite swiftly and simply.

It's not a volume efficient water-bottle. Despite its large size the B'Twin bottle doesn't hold much liquid. In fact for the generous size of the bottle its capacity is remarkably meagre. Even the stated 500ml is a bit optimistic; 450ml is a more realistic measure. That's less than the capacity of a standard small water bottle, but it's as bulky as a 650ml one. Empty it weighs about twice as much as a normal small bidon too, should that matter to you, but significantly less when full, thanks to its reduced liquid capacity.

So it's heavier, bigger and holds less liquid than a standard bottle. It had better do a brilliant job of keeping your drink hot or cold to make up for it.

As an insulated water bottle it's not a complex piece of equipment. Sandwiched between the outer body and the inner liquid holder is a 4mm thick sleeve of foam that performs the insulating duties. A coin of foam insulates the base but the top 55mm of the inner container are uncovered.

The side of the bottle displays a confusing graphic that I think suggests it takes 3 hours for a 90°C liquid to cool down to 35°C, or hold a 23°C liquid at that temperature for that long. I'm not sure. Anyway, it's not an insulated bottle that keeps things their desired temperature for long, and definitely not for three hours.

Pour a hot cup of tea in there – the bottle will hold a good mug full - and in the kind of temperatures you'd want a warm drink to keep your spirits up then it will have gone cold, or tepid at best, in not very much time at all.

Ambient temperature and wind chill are obvious factors in the cooling down and as there wasn't a temperature controlled wind tunnel on hand to accurately document how these different factors changed the effectiveness of the B'Twin bottle only basic going-for-a-ride experiments were done.

Starting at the top end of temperatures where you might fancy a hot drink on a ride, let's say about 8°C, with a stiff breeze it took less than 15 minutes for a bottle of hot drink to go unsatisfactorily luke-warm, and not much longer to go cold with that all too familiar plastic taste. Any drop in external temperature led to a corresponding drop in performance, to the point where by the time you might take your first sip it would already be cold.

It fares better keeping cold liquids at their desired temperature, helped by the cooling effect of air over a moving bottle, but don't expect your iced beverage to remain chilled for very long. If it's a proper hot day you can easily glug down all the contents before it has time to get warm anyway.

The bite valve is easy to use, with a wide rim to get your teeth round, but the bottle responds best to just sucking for sustenance, you'll get nowhere trying to squeeze it to increase flow as you're fighting against two bottles with air and foam trapped between them and squeezing the bottle actually stems the flow.

If you've never felt the need to take a hot or cold drink on a ride, preferring to stop for a proper cup of steaming tea or chilled can of pop, the B'Twin Insulated Water Bottle is unlikely to change your mind.

Verdict

Doesn't work very well at keeping its limited capacity hot or cold