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Platyplus Water Tank Holder
This is the latest iteration in my search for the ideal lightweight way to carry lots of water on my bike.
As someone who frequently participates in long distance events such as brevets with no follow vehicle and long distances between checkpoints, possibly far away from the nearest Wawa or Circle-K, I needed some convenient way of carrying more water than normally possible with frame-mounted water bottles. Also, given the long hours spent on the bike, I didn't want to wear a 100oz bladder on my back with the straps digging into my shoulders. Instead, the goal is to have the bike be the sole beast of burden when it comes to porting water, or in this case, Accelerade mix.
The above picture shows my suitably-equipped bike just before the start of a recent 200k brevet (October 2005) in Southern Arizona (www.azbrevet.com). (Other event items shown above and not normally found on my bike include Profile Wing Clip clip-on aerobars and the Bento Box.)
Details
Previously, I'd graduated from a triangular canvas frame bag to a custom Camelbak bladder holder made out of sailcloth. (See here for the details of the latter system.) However, as with the canvas frame bag, the sailcloth bag occasionally sagged and interfered with pedaling, particularly when the Camelbak was full. Moreover, it was not entirely minimalist in the sense that it was simply a bag designed to hold another bag (the Camelbak).
In this iteration, I do away with the bag-inside-the-bag concept entirely. Instead, a rectangular Platypus 4 liter (140oz) Water Tank (see here) is modified to mount on the bike frame directly. The modifications are as follows:
- The rectangular Platypus bag is folded over and taped to form a roughly triangular shape. Transparent duct tape was used. (The best method would be to cut the bag and re-seal the polyethylene edge. But this requires a plastic bag sealer with the right temperature for the Platypus bag thickness. And it's unclear if I can get one that allows for an optimal convex edge shape - see later.) Anyway, duct-taped, the bag weighs approximately 86g (3oz) and has a current capacity of about 2 liters (70oz) of water when taped up.
[The capacity will be increased to about 90oz in a future iteration. This will come in handy during 100 mile non-stop events.]
- The Platypus bag comes with two black nylon webbing carrying handles. These are attached via eyelets. The handles can be cut off and the eyelet holes re-used. A total of three (readily available) steel 1" L-shaped brackets and two M5 waterbottle cage bolts with wingnuts were combined
to hold the bag securely to the seat tube via waterbottle cage bosses. Given that the water can weigh about 4lbs, the mounts have to be strong. See the close-ups below.
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Bag eyelets
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Lower seat tube attachment point
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Seat tube hardware
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- Notice the bag does not follow the straight line of the downtube because it was folded straight. Due to bulging when filled with water, the bottom therefore becomes concave. It should be re-folded with a convex shape.
- Additionally, one new eyelet was introduced so that the corner of the bag can be velcro-ed to the top tube. This is the weak attachment point. The velcro must be strong and not slip. A frame number eyelet (not present on my frame) would be much more secure. By the way, the standard Platypus Hyperflow bite valve is poorly-designed and not user-friendly. After the brevet, a softer Camelbak bite valve was substituted.
- Finally, the gravity-fed drink tube is velcro-ed to the downtube and goes up to the handlebars. It could be attached more attractively if suitable tube clips that mount to the downtube waterbottle bosses can be found.
The current prototype works better than any of my previous bag systems. The bag is much narrower. This creates plenty of clearance and no interference with pedaling even when completely filled.
Sandiway Fong
Tucson AZ
October 17th 2005
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