Make Your Own Bite-valve Hydration System

Problem to be solved: like many folks who bicycle or hike, I've used bite-valve, hands-free hydration systems for years. Unfortunately commercial hydration systems include a plastic bladder that is easy to puncture, difficult to clean and expensive to replace. In addition, wearing a backpack that holds the bladder is annoying to cyclists. Far preferable for cycling would be to have a bite-valve system that works with a bottle that sits in the frame-mounted bottle cage. Far preferable for both cyclists and hikers would be to replace the dismal plastic bladder with an ordinary PET soda bottle.

The solution in a nutshell: combine a few purchased components with a purpose-designed Delrin stopper in order to make your own bladder-free hydration system!

The hard problem to be solved: bladders collapse when water is removed and PET soda bottles do not. (Well they will eventually, but not before your ears pop!) Therefore make-up air must be added to the bottle when water is removed. The way to do this is mount a small check-valve next to the drinking hose. The difficulty is that bottle tops are small and figuring out how to fit both a drinking hose and check valve was not easy.

Step 1: Design Overview

Design goals:
1. Allow bite valve to be used with PET bottle in bicycle bottle cage.
2. Materials must all be food-safe and easy to clean.
3. Assembly should not leak when shaken or inverted.
4. Parts should be inexpensive and readily available.

Design description:
As shown in the attached drawings, the main effort involves machining a tapered stopper from a delrin rod using a lathe, then tapping 1/8-27 pipe threads in it for a hose barb fitting to attach the 1/4" tygon hose. A check-valve is attached via a short length of 1/8" tygon hose. The 1/8" hose is slipped onto a short length of 0.134" hypodermic tubing that is pounded into a 0.128" hole that is drilled through the stopper. The check-valve is secured to the 1/4" hose via a dab of silicone caulk on the side. The stopper is held securely into a water bottle using an ordinary soda bottle cap through which a hole has been cut using a 3/4" punch. A short length of 1/4" hose is used to attach the acetal quick-disconnect coupling socket with valve, and then a longer run (perhaps two feet) goes from an acetal quick-disconnect coupling plug to the bite valve. The bottle is inserted in the bottle cage and the bite valve is attached to the handlebar with a pair of nylon loop straps.

Email me (alchaiken at gmail dot com) if you would like a DXF format version of the drawings for this project.

Step 2: Parts List: Commercial

The project uses some purchased components plus some raw stock materials that must be transformed in a machine shop.

Commercial parts that go into the final product unmodified:

-- CamelBak Big Bite Valve, $5.95 each from Mountain Sports Online, part number 016805
-- White Polyethylene Single-barb Tube Fitting, Coupling For 1/4" Tube , $4.74 each from McMaster-Carr, part number 2808K106
-- 304 stainless steel regular-wall 0.134" diameter hypodermic tubing, $4.85/foot from SmallParts, part number HTX-10R
-- Supravalve Polycarbonate Check Valve, 1/8" tube fitting, $4.50 each from SmallParts, part number CVP-02
-- Smooth-Bore High-Purity Clear Tygon Tubing 1/4" ID, 3/8" OD, 1/16" Wall Thickness, $1.84/foot from McMaster-Carr, part number 5466K14
-- Smooth-Bore High-Purity Clear Tygon Tubing 1/8" ID, 1/4" OD, 1/16" Wall Thickness, $1.58/foot from McMaster-Carr, part number 5466K12
-- Polypropylene Quick-Disconnect Tube Coupling Socket, 1/4" Size, for 1/4" Tube ID, with Valve, $11.77 each from McMaster-Carr, part number 51545K73
-- Polypropylene Quick-disconnect Tube Coupling, Plug, 1/4" Size, For 1/4" Tube Id, W/o Valve, $2.37 each from McMaster-Carr, part number 51545K69
-- Nylon Loop Strap for 1/4" OD, $5.12 per Pack of 100 from McMaster-Carr, part number 8876T13
-- Nylon Loop Strap for 1" OD, $12.46 per pack of 100 from McMaster-Carr, part number 8876T42
-- Black double-sided velcro, available from Fry's or Michael's Crafts, lifetime supply $16.99
-- GE Max5000 Siliconized Acrylic Caulk, available for cheap at hardware stores near you
-- PET soda bottle, available for free from a recyling bin near you! Many brands of drinking water and soda work well with this design, although Coca-Cola bottles have too few threads.

The total cost of commercial parts to make one unit as of January 2008 is about $29 although you could save by purchasing the parts in larger quantities.

For valve-switchable two-tank system, add

-- 3-Way Stopcock With 2mm Bore, US Plastic part number 17223, $44.11 in single quantities.

Step 3: Parts List Part 2: Raw Materials

Here I list the parts that are not used as-purchased but must be transformed in a machine shop such as TechShop.

To make the stopper itself:
-- White Delrin Rod, 1-1/4" Diameter, $6.39/foot, McMaster-Carr, part number 8572K233

One-time purchases to make the tooling that holds the stopper during cutting of threads:
-- Alloy 6061 Aluminum Oversize Sheet, .500" Thick, 8" X 8", $30.02, McMaster-Carr, part number 89155K42
-- Alloy 6061 Aluminum Sheet, .190" Thick, 12" X 12", $35.19, McMaster-Carr, art number 89015K31
-- some 8-32 countersink-head machine screws, about 3/4" long
-- some 10-32 socket-head cap screws, about 1" long

Step 4: Tools

I fabricated my parts at TechShop in Menlo Park, California. Some of the tools that I mention below I purchased, while in other cases I simply used parts available at TechShop.

Machine tools:
-- metal turning lathe;
-- Bridgeport-style vertical milling machine;
-- band saw.

Hand tools:
-- Small-diameter Hole Punch, 3/4" Hole Diameter, Trade Size 18, $17.91 from McMaster-Carr, part number 3424A51;
-- 1/8-27 NPT tap and tap handle;
-- 1/2" shank micro tap guide, $14.48, MSC Direct part number 95267472 ;
-- No. 30 slow speed drill for brass, $2.98, MSC Direct part number 01388305 ;
-- Letter Q high speed drill, $8.40, MSC Direct part number 01149178 ;
-- Allen wrench set (for 10-32 cap screws);
-- Philips screwdriver (for 8-32 machine screws);
-- Small hammer (for pounding hypo tubing and punching bottle caps);
-- Small tubing cutter (for hypo tubing);
-- Files and deburring tools.

Step 5: Fabricating the Tapered Stopper

The following discussion assumes some basic knowledge of how to use a lathe.

1. Chuck up the 1 1/4" delrin rod and mount a sharp cutting tool.
2. Using the highest possible speed for this and following steps, face off the end.
3. Set the angle of the cross carriage to 6 degrees so that the small end of the taper will be at the free end of the rod. (Setting the cross carriage angle now minimizes measurement steps later on.)
4. Turn the OD of the rod down to 0.972" on the entire exposed end of the rod.
5. Turn the last 0.56" of the rod down to 0.86".
6. Cut a 6 degree taper on the 0.56" section, leaving the OD of the small end of the rod at 0.76".
7. Moving 0.64" away from the free end, part off the stopper.

Step 6: Drilling the Holes and Tapping the Threads

This section assumes some very basic knowledge of how to use a vertical milling machine. It also assumes that you have already fabricated the tooling necessary to hold the delrin stopper during this step, or its equivalent. Fabrication of the tooling is described in Appendix A.

1. Use a deburring tool or file to remove any nub left by the parting-off on the lathe.
2. Mount the stopper in the tooling and tighten down the screws, making sure that the clamp on the top is level.
3. Mount the tooling in the vise of a milling machine, and use an edge-finder to locate its corner, setting both digital read-outs to zero.
4. Use the drawing to center a Q-sized drill bit over the large hole. Drill through.
5. Put a spring-loaded tap guide in the check to keep a 1/8-27 NPT (tapered) tap oriented vertically while you tap threads for the hose barb.
6. Use a #30 drill to make the hole for the hypodermic tubing.

Step 7: Final Assembly of System

In this step, we assemble the components together and test them as a unit.

1. Use a tubing cutter to make a length of hypodermic tubing about 1/2" long.
2. With a hemostat or similar pliers, hold the tubing section about the small hole and gently tap in about 1/8" deep using a small hammer.
3. With the stopper clamped back in the tooling, use a wrench to tighten down the hose-barb fitting.
4. With a scissors, cut a short (2") length of 1/8" tygon hose and slip it onto the hypo tubing.
5. Cut as long a section of 1/4" tygon hose for the draw tube as you will need. Might as well use a long section, as you can shorten it later. Slip it onto the 1/4" hose barb.
6. Place a soda bottle cap threaded side up on a block of wood and, with the small hammer, use a 7/8" punch to make as centered a hole as you can. Slip the cap over the tygon hoses.
7. Blow into the check-valve to see which way it opens. Insert one end into the 1/8" tubing so that make-up air will be able to enter the soda bottle.
8. Place a dab of caulk between the check-valve and the 1/4" hose. The caulk will help to keep the check-valve from falling off when you hit a bump.
9. Holding another section of 1/4" tygon up to your soda bottle, cut a pick-up tube that will just reach from the bottom hole in the stopper to the bottom. Cut the bottom of the tube at an angle. Stick your pickup-tube in the bottom of the stopper.
10. Fill a bottle with water. Place the assembly on top and tighten the threads. Pinching off the 1/4" hose, invert the bottle. Does it leak? If not, success!

Step 8: Installation on Bicycle

Details of the bicycle installation will depend on the dimensions of the bicycle and whether you plan to put the bottle in a cage or mount it on a rack.

1. Cut a piece of 1/4"-diameter tygon hose that's long enough to reach from your stopper to the bottom of your bottle. Cut both ends at an angle so that the draw tube won't stick on the bottom. Stuff one end of the draw tube in the hole on the bottom of the stopper.

2. Mount your stopper and draw tube assembly onto a bottle and place it into the frame-mounted bottle cage. Repeat with a second bottle if desired Doesn't that look cool? Isn't being a nerd fun?

3. Insert a quick-connect with anti-siphon valve into the tube at the top of the stopper. Insert a matching quick-connect into a long section of 1/4" tygon and snap the two fittings together. Cut the long tube to the desired length for the draw tube. Mount the bite valve on the end.

4. Put a 1/4" cable clamp around the draw tube and position it over the handlebar. Put a larger cable clamp around the handlebar and connect the two cable clamps together using a screw. You may want to use a piece of inner tube to keep the larger cable clamp from slipping on the bar. Once the draw tube is attached, you can pull the tube back and forth through the cable clamp to adjust the length.

5. Unsnap the draw tube from the first bottle and use more quick-connects and 1/4"-hose to make an extension tube for the second bottle. Use velcro or cable clamps to attach the extension tube to the top tube of the bike.

6. Fill your bottles and go for a ride! Riding is why we went to all this trouble, remember?

Step 9: Desired Improvements

1. Make the plastic parts in one piece using an injection molder. I know that there are services like Proto-Mold that will do small injection-mold runs, but I don't want to spend a lot of money, and would like to play with the injection molder myself. Anyone here in the San Francisco Bay Area have an injection molder that will accommodate a food-safe plastic?

2. I've added a three-way wye valve that will allow me to switch between two bottles with a twist of a knob while pedalling hard. I'm using this most excellent nalgene stopcock but it's very expensive. Anyone know of a similar food-safe product at a more reasonable price?

3. Make it easier to pour powders and squirt gels into the bottles . . . the small opening compared to ordinary bike water bottles is a disadvantage.

4. Find cheap replacements or less expensive sources for the pricier components.

Step 10: Claims (for Legal Purposes)

I wish to publish this invention with the Creative Commons license and wish to make explicit that I claim the following novel aspects:

1. a bite-valve hydration system that works with an ordinary soda bottle;
2. furthermore, a system that works with a bottle placed in a bicycle bottle cage;
3. a system that works with a bottle strapped to a bicycle rack;
4. a system that utilizes a check-valve along with a container that does not collapse when water is removed;
5. a system that utilizes a pick-up tube that allows fluids and gels to be drawn from the container bottom;
6. a system where the bite-valve tube is attached to the handlebar, for example with a cable clamp;
7. a system for a bicycle where tygon tubing is routed along the bicycle's top tube, for example with velcro;
8. a system which utilizes quick-disconnect tube couplings to allow easy bottle change;
9. a system which utilizes a quick-disconnect tube coupling with a valve to prevent leakage and provide an anti-siphon-back feature for the tube.

This invention is Open-Source Hardware and has been reduced to practice. Its invention by me has been observed by dozens of members of TechShop and the Almaden Cycle Touring Club. The system was described and demonstrated to a meeting of the Make:SF group on January 7, 2008. Any attempt to patent a bite-valve hydration system that works with a soda bottle and is mounted on a bicycle as described above should be blocked by the Prior Art represented by this Instructable.

The photo is from the January 7, 2008 TechShop demo and was taken by Sherry Huss of O'Reilly.

Step 11: Credits and Acknowledgements

Two-dimensional CAD drawings were made using QCad. I took a lathe class from Jim Newton and a mill class from Alec Aisner. Many folks at TechShopTechShop offered valuable advice and encouragement, especially Lloyd Stafford and Chris Tacklind. I also appreciate the expertise of Jim and Paula Vanderpool at Dan-Mar Tool in San Carlos, CA. Special thanks to Barry Burr for suggesting the silicone caulk and the bottle cap punch.

Step 12: Appendix 1: the Hiking Version of the Homemade Bite-valve System

The 1 psi (1/15th of an atmosphere) pop-off valve is not adequate to allow a pickup tube to draw from the bottom of a vertical, upright two-liter soda bottle for hiking purposes. The solution is to invert the bottle and draw from the bottom. Drawing from the bottom requires no pickup tube but it does mean that the pop-off valve is best kept protected inside the bottle, where it won't get knocked off. A hiking version of the bite-valve system is therefore the same as the cycling version except that

1. the hypo tubing and pop-off valve are on the inside;
2. there's no pickup tube;
3. it's more convenient to use a right-angle poly hose barb.

For the 2-liter horizontal bottle attached to the bicycle rack as shown on the first page, I used an external pop-off and a draw tube, although tilting the bottle a bit makes the draw tube unnecessary.

Step 13: Appendix 2: Maintenance

I don't clean the bottles or tubing used with this system: I just throw them away and replace them. However, in order to keep the stoppers clean, I do flush them with warm soapy water and then rinse them after every ride where they are exposed to sugary sports drinks. After rides where I drink water only, I just drain the system down and let it dry.

I end up replacing the bottles and tygon hose after perhaps 50 hours of use. Every 200 hours or so, the check-valve begins to look a bit nasty, and I replace it as well. When that happens, I soak the whole stopper assembly in a dilute bleach solution, then rinse and dry well.

Step 14: New Two-tank Mixer and Switcher Valve

The recent addition of the U.S. Plastics valve makes possible one-handed switching between the two tanks. The previous method of disconnecting one quick-disconnect and connecting the other required two hands and was too tricky for me to do while riding. Also, the valve allows mixing of the two tanks! Sometimes I run one tank with water and one with sports drink and switch back and forth.

The second photo is a detail of the valve showing how I've stretched a piece of old inner tube over the bottom half of it. The valve tended to chatter on the top tube during fast bumpy descents, but the inner tube section solves this problem, and I just happened to have an old inner tube on hand.

Unfortunately, the valve costs more ($44) than the rest of the system combined ($29)! If someone knows of a cheaper source for a 3-way stopcock, I would be pleased to learn of it.