Walmart Hack Bamboo Bike




Introduction: Walmart Hack Bamboo Bike

When I designed the Semester hextube bamboo bike for HERObike a few years ago, I was frustrated with the costs of components- wheels, tires, chainset, saddle- everything! Trying to keep a simple bike affordable was an incredible challenge. But then someone told me that Walmart sold a pretty decent fixed/ single speed bike for $100 retail. With the help of my students at the University of Kansas, I quickly devised a way to hack this bike, replace the top tube and the down tube with bamboo/carbon fiber hextubes and Voila! the Walmart Hack was born. You're still probably looking at $200 by the time you're finished, but you have a unique single speed/ fixie with a smooth, vibration-free ride!

Step 1:

Start with an inexpensive fixed gear bike. Look for steel frames that are filet brazed with small top and down tubes. The Walmart Thruster 700c is a good candidate.

Step 2: Make Your Hextubes

Check out my other Instructable about making bamboo/carbon fiber hextubes. If you have big bamboo growing nearby, you're in luck! Otherwise, look around for bamboo strips that are about 2' long, minimum 1" wide, and approximately 1/4" thick. If all else fails, get some nice hardwood (maple is a good choice), have it planed down to a 4-5mm thickness. You need to calculate the size of your strips based on the dimensions you need for your hextubes.The inside diameter of the hextube must be slightly larger than the diameter of the tube you are replacing. Let's say you are replacing a 28.6mm tube. The inside diameter of your hextube should be slightly larger- say 30mm.If you are using 4mm thick bamboo, the outside diameter of the hextube (flat to flat) is 38mm.If we use a little math (or an online calculator) we know that each side is 21mm. That is the width of our strips. Length should be a couple inches longer than we need to allow for trimming.

Step 3: Prepare Your Frame

Scary step, but not difficult. Just make sure you measure everything.
First, measure your top and down tube diameters. The down tube is going to be a little bigger so you need to make your tubes different sizes. You will use these measurements to calculate the size of your hextubes. Next, carefully measure the length of the top tube and the down tube. Usually, tube lengths are measured center-to-center. This way, when you install the hextubes you won't change the geometry of the frame. Use a Sharpie to mark your cuts, so your lugs are 80-100mm long, then saw your frame. Rough up the "lugs" that will go inside our hextubes, and tape off the rest of your frame to protect it.

Step 4: Fit Your Tubes

Dry fit your hextubes and carefully shape the hextube to fit tightly to the steel frame pieces. I usually mark with a pencil, cuut with a coping saw, then shape with a rasp. Keep checking the fit to make sure your finished frame will be the same size as the old one. The care you take in this step will determine the overall quality, look and feel of the finished bike. When your tubes fit dry, pull them apart, clean the tubes to make sure there is no grease anywhere, them slather a generous amount of JB Weld or PC7 on the lugs and inside the hextubes. Check to see that your frame is square. Leave overnight. Then take off the tape and reinstall components.

Step 5: Testride!

This is the best part. Be careful at first, in case the frame got misaligned or one of your epoxy joints wasn't set right. Slowly increase speed and distance. Notice how smooth the ride is. Because the hextubes are made by fusing two dissimilar materials (bamboo and carbon fiber) vibration in these tubes is nearly eliminated! Enjoy!



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    18 Discussions

    Cool Idea, for those who don't know Bamboo absorbs the vibration from the road in much the way a suspension does and makes the ride smoother. Google it folks.

    2 replies

    It's not the same. Bamboo provides short travel dampening of high frequency vibrations while a regular suspension provides long travel dampening, adds weight, and reduces drivetrain efficiency when it has a rear suspension.

    In other words only a fool picks a bike with a suspension for road use and only a fool picks a bamboo frame mod alternative for mountain bike use.

    For someone who wants to do a little of both casually on the same bike, the best compromise would be leave the frame alone and go with a hardtail (with front suspension).

    Call me a fool, but I love full rigid mountain bikes and I feel like a bamboo full rigid would be a pretty darn fun ride.

    Note that there's carbon fiber too. People do make bike frames out of carbon fiber tubes alone without the bamboo over them. "IF" done right, the weakest link (unless you run into a tree or get hit by a car) tends to be the epoxied together ends, not the material used. It might be kind of retro and amusing if the ends of the tubes had hemp rope lashings over them for reinforcement.

    There are lots of these out there. You might notice in one of the photos a group of students who all built their hacked Walmart bikes as described. Of course, any bike frame improperly built is dangerous!

    you haven't really explained the benefits of cutting up a perfectly well built and properly welded steel frame bicycle.
    epoxy can be extremely brittle under impact loading such as you would get in the joints you are cutting.

    1 reply

    JBWeld is fairly brittle but there are many common epoxies that aren't, unless it is very, very cold. Regardless I wouldn't feel nearly as safe on a DIY frame mod without lengthly testing, failure, and redesign to get it right for each particular bike frameit's to be used on. One thing I am fairly confident of is the first try will not be anywhere near as durable as the original frame was, but then on a road bike some people never get close to needing a frame as durable as the original is.

    Even so, I'm not disagreeing that cutting up a perfectly good bike is not the right answer for everyone and that includes me. I'd wear padded gloves and padded shorts or seat if I decided that the vibration was excessive on a particular route.


    2 years ago

    What's the reason for creating a cool looking bike like this? is it the looks, or is the riding behavior improved as well?

    When it's only the looks, could you not glue the bamboo around the tubes, without cutting the bike in half?

    2 replies

    Did you not read the text? If done right it's supposed to dampen vibration for a more comfortable rid.

    heh, replace "rid" with "ride" above.


    2 years ago

    If you're mainly looking for cheap bike parts visit thrift stores, Salvation Army, Goodwill, etc. Even garage sales! If you're going to hack a bike start with something cheap. That way you recycle an old bike as well...

    1 reply

    So you pour more time and expense into something that's junk.

    I couldn't disagree more. As silly as it is to make this frame mod, if it's worth doing then it's worth doing right.

    Do it to a bike with decent components so what you end up with is a good bike rather than junk that's still junk except for the frame mod.

    Hint: If there weren't dozens of things wrong with $100 department store bikes then nobody would pay multiple times as much. A bicycle is a modest expense considering it can last a lifetime and promote health while doing so.

    If you have time to ride you have time to get a job and earn a few hundred for a decent entry level major brand bike, -OR- go used major brand but not so much at Salvation Army or Goodwill (unless you live in an area where bicycles are EXTREMELY prevalent and can't even be given away) but rather eBay, Craigslist, or a local bike shop.


    2 years ago

    Actually, bamboo is a fibrous material composed mainly of carbon - is it not?


    2 years ago

    Also the front fork connection at the steering post - high stress


    2 years ago

    Talk about "carbon fiber", please check this out. Don't know how the pedal arms are made. Probably the most highly stressed components.

    I am not sold on the bamboo bike concept. The argument about sustainability etc. don't appeal too much. The steel or alum. used in a bike frame could be recycled over and over. To me it does not make sense to build a bike from bamboo and use a ton of chemical adhesives. If it was practical, it would already be done by the industry, especially in the lands where bamboo is plentiful.