Why did someone buy a $1000 camera only to use it twice? It makes me wonder how much better the world would be if the consumerism in our lives was based around leasing, renting or time-sharing nice things. It would encourage manufacturers to build our things with longevity in mind, and as soon as you realize you don’t use that guitar or table saw as much as you thought you would, then you can just return it and save on your monthly “stuff” bill.

Anyhow, enough rambling, here is a shot of whambam outside a pub in Oxford. It is processed in pseudo-HDR.

My first thought was to swap it over to a single-speed, especially since the wheelset I was using already had a flip-flop hub and a freewheel on one side. However, this would require building a brake mount into the seat stays, which would apply a force right in the middle of the seat stays, perpendicular to the load they were intended for. The would probably be strong enough, but without load testing, I wouldn’t really be comfortable with that setup. Imagine the catastrophic failure potential: blowing out the seat stays under heavy braking… not good.

So then I settled on a coaster brake, which would require a new rear wheel. This is the result:

While I was at it, I also had to repair the seat post mount. The original method I used to mount the seat post turned out to be highly ineffective. Basically after about an hour of riding, the bond between the piece of steel and the carbon broke.

Old seat post mount: I rebuilt it by cutting off the top 2cm, wrapping a seat post in a non-stick tape, and laying up some carbon. Once it cured, I cut the carbon with a hack saw to create space for the clamp to squeeze the tube. Hopefully this will work.

Here are a few close pictures of the joints

Since I didn’t have my choice of donor bike, the head tube is too short for me. To overcome this, I got a $20 fork with a long steerer tube, and made a nice looking bamboo spacer. Now the bars are the right height. Unfortunately, I think I grabbed a fork for a 27inch wheel, which is designed for a front wheel that is 14mm smaller in diameter then the 700c wheels I am using. I was able to file it down to fit, but I can’t fit it with brakes. I will replace it with a 80s carbon fork. They occasionally come up pretty cheap on eBay, they look pretty cool, and they are light weight. I can’t use a standard fork, because the head tube is for a 1 inch threaded fork rather than the standard 1 1/4 inch threadless.

The bike weighs in at 21.5lbs. Thats fairly light, but heavier than I was aiming for. The fork I have on right now is very heavy, so I should be able to shave 1.5 to 2 lbs with a carbon fork, bringing it into line with what I was going for. It has now joined my stable.

1. Carbon fiber tow, basically 5mm wide unwoven carbon fiber (find it on eBay)

2. Epoxy resin and hardener suitable for use with carbon fiber

3. 100 grit sand paper

4. Cheap paint brushes (get at least 5, you will throw one out after every batch of epoxy sets)

5. Lots of pairs of gloves

6. Plastic masking material

7. Ideally a gram scale, but disposable volume measures will due (such as shot glasses)

I would have taken more pictures, but with wet epoxy everywhere it was a real challenge.

Start by mixing up a batch of epoxy. Be sure to follow the directions because mixing ratios vary. Also, you should be well aware of the working time, as it can range from a couple minutes to a few hours.

Next you should paint it onto the part. The surfaces should all be rough, so sand first if necessary.

Then wrap the wet surface with carbon fiber tow until it starts to look dry. Wrap a couple more layers and then paint on some more epoxy. It is easiest if you spool off 20 or 30 meters at a time onto a smaller spool so you can get around tricky corners. They key is to ensure that you wrap in all the directions where load is expected to be applied. Remember, carbon fiber is only strong in the direction of the tow, so if you don’t wrap in a direction where load is applied, the joint will fail.

The wet layup took about 4 hours, and the working time for the epoxy we used was just over an hour, so we made three pots. After 48 hours of curing time, the joints were strong!

First we had to figure out how to get the frame to be straight in all the appropriate dimensions. If we end up building more in the future, then we will build a jig, however I think for a one-off a jig is a bit overkill. That being said, a using a jig is really the ideal way to do this step, so the following is not so much a set of instructions as it is an explanation of how I tacked my frame together. Please take that into consideration if you make your own bamboo bike.

I had decided to use the steel chain stays from the donor bike partly because of the tension, compression and torque loads that are applied on them when riding, and also to help with getting the whole bike to be straight and true. It was a trade-off because I had to compromise with a longer than desirable wheelbase, and I would have liked to build the whole bike out of bamboo (I even treated, cut and mitred bamboo chain stays), but in the end I think I made the right choice.

We (Jame Kay, who was invaluable in this phase of the build, and I) started by tacking the seat tube the bottom bracket shell, which was conveniently already attached to the chain stays. To get it to set straight, we put on the rear wheel, put a spacer between the wheels and the seat tube, and sighted from behind the wheel to ensure it was straight up. Once we were satisfied this would work, we popped the seat tube off, slapped some 5-minute epoxy on the joint, and then taped it all in place.

Next we attached the seat stays. Once problem we noticed was that a compression force between the seat stays and the dropouts (which is the load they will experience when the bike is riden), creates an outward force on the bottom end of the stays. As such, they will at best shift a little as the bamboo compresses between the dropouts and the carbon layup, but more likely they would split. To address this, Jame thought of putting a washer underneath so that the force would be translated directly upwards. As I didn’t have the right size washer on hand, Jame cut a fairlead in half, removed the plastic, and voila! We 5-minute epoxed it all together and used electrical tape to hold it in place until the epoxy set. The nice thing about electrical tape is that epoxy does not bond to it. Do not use masking tape with epoxy!

Finally we had to tack on the top tube, down tube and head tube (which form the front triangle). This part is really tricky because you have to make sure that the whole front triangle is set in line with the rear triangle, while at the same time ensuring that the head tube is directly vertical. Starting with very well mitred joints really helps here because everything more or less lines itself up, you just have to fine tune to get it bang on.

We first installed the headset and fork so that when the frame is leaning forward on the front dropouts, we would know that the head tube is vertical. Then we used a clever little trick I am calling the “bungee method”. It is a modification of Sheldon Brown’s “string method” for ensuring that a steel frame is aligned after spreading the rear triangle to accept a wider rear axel. By using a bungee rather than a string, the bungee serves the dual purpose of ensuring alignment, and holding the parts together while the epoxy sets. I ran a piece of bungee through both dropouts and around the head tube, then tied it so that there was a decent amount of tension. Then we epoxied each joint, and rested the frame on the bottom bracket shell and the front dropouts. We measured and adjusted the alignment continuously until the epoxy set. As you can see in the second picture below, the gap between the right (from a rider’s perspective) bungee and the top tube is larger than the gap between the left bungee and the top tube. That indicates that the alignment needs adjustment.

With the 5-minute epoxy set, the frame was assembled, tacked, and ready for the wet layup. I should have been more excited in this picture, except that it was starting to get late and we still had a lot of work to do.

After a little brain storming, we decided to use a drill press. By using a hole cutting bit, we were able to drill a hole the size of the tube to be joined to and at the correct angle. Since the angles were all fairly rough, and I was cutting everything over length to allow for fine tuning later, the process only took an hour or two once I got going (after some excellent training from the McFarlane’s of course). Essentially the steps are as follows:

1. measure the size of the tube to be joined to and select the right bit size

2. measure the angle and set up that angle on the drill press

3. drill out the desired hole size at the desired angle

Next I had to measure it all up again, and file by hand to create a perfect fit. This took a long long time. Seriously, it took a while. But in the end, I think did a pretty good job.

The easy thing would have been to cut up the track frame from my donor bike. It was about my size, so I could replace the steel sections, one at a time, making only small adjustments to the frame size. That, however, would go against my goal of minimizing waste. Instead, I sold that perfectly good frame so it can be used for years to come, and I am using a circa 1980 steel frame Norco road bike which has clearly reached the end of its useful life. The brakes were shot, as was the derailer and tires. The wheels needed truing, and the bottom bracket had a very significant amount of play in it. The bike could have been restored, but it was at best an entry level bike 30 years ago, so it was not really worth the cost to restore. As a side note, I just finished restoring my dad’s 70-something Guerciotti to new condition, and it cost well over $1000.

The first step was to assess what I could use which parts could be useful on this bike. My original plan was to just use the bottom bracket shell, head tube and drop outs, and I was going to get a carbon fork. However, on closer inspection, the rust on the fork is surface level only, so I will brush the paint and rust off and wrap it in the leftover carbon from my frame layup. I can also use the stem, and I will keep the chain stays, wrapping them in carbon for extra strength (and look). I also found that the headset was surprisingly usable. None of the bearings had cracked, and there was only light grooving in the bearing seat. It seemed as if it hadn’t had the bearings cleaned and greased in over a decade, but one of the great things about these old road bikes is that everything is designed to be rebuild able. Sealed cartridges are nice, but when they need to be rebuilt, you often either have to ship them back to the supplier or throw them out.

Next I had to take all the parts off, and hack off the frame parts that I will keep, and then grind off all the paint to prep them for the layup. I ran into a snag when I tried to remove the cranks. I have the right tools to remove the bottom bracket, but I don’t have a square taper crank puller. I dropped it off at my LBS (Jubilee Cycles), but being June, they were too busy to pop them off on the spot. I could only get as far as prepping the head tube. To be continued…