The CrankTank4 from the Australian cyclists at Adventure Hydration puts 4L of water into the same space as two regular water bottles, keeping you hydrated longer, saving space, money & weight in the process. At the Atlas Mountain Race last month, our friend & Euro adventure racer The Chimp spotted UK-rider Chris Herbert’s alloy Cannondale Topstone among dozens of finisher bikes, and keyed in on the CrankTank nestled in his front triangle. We looked into it, got the full details, and now think we should probably get ahold of our own frame-mounted hydration reservoir…
CrankTank4 rigid frame-mounted hydration reservoir water tank
The Adventure Hydration CrankTank4 concept is pretty simple… for longer adventure riding two bottles often just isn’t enough, so how can you pack more water storage into the same space? Especially on bikepacking setups, where frame bags are already fighting for room, standard bottles just aren’t an efficient use of space. Sideload cages help a bit; cageless designs like Fidlock do it even better; but still we’ve seen better use of tight space by stuffing hydration bladders from our Camelbaks into bikepacking bags themselves, adapting TT hydration between aerobars, or even building in custom bladders.
But the CrankTank4 solution is even more simple. A rigid 4L polyethylene tank that sits just above your cranks. Molded-in channels let it tuck in against your seat & down tubes, while two big velcro straps secure it in place. Securely mounted, yet still super fast & easy to remove. Then, a long insulated hose like any hydration pack carries water up to a bite valve that you can mount to the handlebar.
For riders exploring more remote areas, those riding in extremely hot & dry environments, or just cyclists looking to be more self-sustaining while out on tour, it’s hard to argue with the ability to pack 4L of water into the same place as a 750ml and a 500ml bottle.
CrankTank sizing & fit
CrankTank4 is available as a single rigid size & shape, so it isn’t going to fit every bike, or every rider for that matter. But its design is simple and quite adaptable, so most traditional double triangle / diamond-shaped frames will work – from dropbar road or gravel, to flat bar front suspension mountain bikes.
The tank itself is at maximum 112mm wide at the top where it hits the seattube, tapering to just 74mm wide where the top meets the downtube. That sounds wide at first glance, but the bottle cages on the all-road bike I rode to work today measure 90mm empty, 95mm with a bottle in them, and I measured 118mm between the inside of my Ultegra road cranks at the pedals. So, I suspect the vast majority of cyclists will have plenty of clearance between the tank and their legs. The CrankTank4 also gets an indentation down 69mm wide near the cranks to clear any standard 1x or 2x chainrings.
Dimensions-wise the tank is about 230mm tall along the seat tube & 275mm long along the downtube. How it sits in the frame depends a bit on the shape & size of frame tubing and frame angles, but ultimately if your bike fits two bottles in cages, it will fit the CrankTank4. More conventional geometry sits the tank closer to the crank for a lower center of mass. Mountain bikes with steeper, suspension corrected down tubes and curved seat tubes will sit the tank a bit higher (4cm higher from the BB on this Marin trail bike than the Curve gravel bike above.)
An extra Wedgie mount is also available for bikes with frame tubes larger than ~50mm diameter or totally flat. It essentially mounts a plastic bar to support the tank when frame tube shapes are too wide or squared off.
But isn’t the water too low to drink comfortably?
Anyone who has used a hydration pack knows that it can be a lot of effort to suck water through a long hose. With the water located low in the frame, Adventure Hydration designed their system for increased water flow. While the smallest point in some of the most popular hydration setups (Camelbak, apparently) is 4.8mm in diameter, the smallest diameter in CrankTank4 is 5.6mm diameter, for 35% more cross section area and 1/3 more flow capability. Adventure Hydration says compared to other hydration packs, the effort to suck water out of the CrankTank4 is “somewhere between the best and worst”.
The CrankTank comes with a 120cm/47″ long drinking tube so even taller riders can drink sitting upright with ease. And it includes a strap-on tube keeper clip that most riders attach to the handlebar to keep the tube secure & easily accessible, wrapped around the cockpit while riding.
First debuted late last year, the 4L polyethylene tank is now available in three colors: translucent white, opaque grey, and now translucent grey. The translucent tanks let you see how much water is inside. Then, the tanks caps, tube keeper clips & optional Wedgie mount (which are all 3D-printed) come in white, orange, and now blue.
The 3D printed point is important, as it has allowed Adventure Hydration to make running updates to the fittings based on early rider feedback, even though the just started selling last October. The new cap (blue, above) gets a slightly canted valve connection which improves clearance to bikepacking bags mounted in the extra upper space inside the front triangle. (The original straight version will still be available on request.)
CrankTank4 water reservoir – Pricing, justification & availability
If you are comparing it to the price of the couple of water bottles being replaced, the A$110 pricetag for the CrankTank4 might seem steep. But let’s step back for a second. First, 110 Australian Dollars is only ~$67 USD or 60€, global shipping is going to bring that back up, but…
This claimed 480g setup replaces more than five large 750ml water bottles and the need for those five water bottle cages. Let’s say you like Camelbak Podium bottles (which are only 710ml actually). Five of those at $11/12€ and another $8/6€ each for those ultra-cheap Decathlon Triban bottle cages, and it will still cost you $95/90€ (~A$160), require five sets of bottle bosses, weigh more at 625g (not even counting bolts), and hold less… only 3.6L of water. It’s starting to sound like a solid deal.
Plus, while you are hydration shopping, Adventure Hydration also offers a A$45 fitted neoprene cover that offers 4mm of insulation & protection, whether you are staving off the hot Australian sun or sub-freezing temps (and a limited edition cover decorated by a native Nukunu artist from the Southern Flinders Ranges region where Adventure Hydration is based.) Other individual replacement parts are also available, as is a plain cap for anyone want to use the CrankTank just as an auxiliary water reservoir.
The latest CrankTank4 is available to order now, with shipping estimates from the end of next week. For now the 4L model is the only one available, but Adventure Hydration has hinted that if interest is good, a smaller & even more compact version could be in the works, too.