Arcturus' Travels » Bicycle Construction

Tandem Milestone:

Gary — Thu, 06 Oct 2011 03:04:23 +0000

Today I finally was able to install the key assembly in the power train for the new tandem. This assembly is a jack shaft that allows the blending of power from the rider and the auxiliary electric motor. That is the rider can power the wheel with no auxiliary power. The auxiliary motor can power the wheel and the rider can coast. Finally both can power the wheel at the same time.
At the same time the shaft itself functions as the pivot for the rear wheel suspension. This is good because the chains don’t vary in length as the suspension flexes.

This is the New Power Distribution Assembly

The next task is to configure the front wheel drive. It will be pedal power only. The tricky part will be that the pedals will remain fixed to the frame and the chain will have to bend with the steering. I have ridden another person’s bicycle with a bending chain drive so I know it will work. I just have to position some idlers at the perfect point.
It was exasperating trying to compete this task today. The rainy season has started in Hillsboro where we are staying. We would get a delightful “sun break” and I would unload the bicycles and start working on the shaft with the lathe. About then the light would go away and a cold rain squall would descend on us. I would quickly return the bicycles to the trailer, lock up and retreat to the warmth of the coach. Half an hour later the sun would be back. Out comes the bicycles again and I would get back to work. Repeat the scenario several times.
The other complication occurred when I started to drill the setscrew pilot holes in the collar that locks the shaft in place. I wanted three equally spaced setscrews in the collar. I have the perfect tool, a dividing engine that allows you to rotate the part with exact precision. I dug it out of the tool chest and was horrified to see that it had rusted in the damp air. I spent about two hours disassembling the tool and polishing each part and carefully oiling and reassembling it. When compete I mounted the collar and drilled three pilot holes at exactly 120 degrees from each other.
We need to get out of this damp weather and back to the warm dry part of the country.
These years I have written extensively about “Path” the green dragon. This is our recumbent tandem bicycle. I designed and built “Path” back in 2001 and he has been our trusty steed these ten years and 13,701 miles. Path replaced our regular garden variety upright tandem named “The Purple People Eater,” (because it is purple, of course.)” Purple” has 8,428 miles on his odometer. Last week “Purple” came out of retirement and will replace “Path” as our ride of choice.
What I need to explain is that “Path” is harder to balance on. There are two reasons. First: we are closer to the ground so you have to correct for errors in balance quickly. Second: because my feet swing with the whole front end of the bicycle to steer, it takes more strength and coordination to ride a nice straight path at the edge of traffic. Over the past year my balance has been deteriorating and it now takes most of the lane to keep my balance. In April of this year my diagnosis was confirmed, I am in the early stages of Parkinson’s disease.
The new tandem will be designed for Judy to be the captain. I will become the stoker. As soon as we can finish up the new tandem we will probably retire “Purple” again. In the meantime I expect to hear “Shift!” from the back seat every time I start lugging the cadence, and I will have to remember to yell “bump” when a chuck hole rears up.

Look Ma, No Brakes!

Gary — Fri, 06 May 2011 04:43:12 +0000

We are celebrating today, Cinco de Mayo, but is has no connection to the 1862 battle of Puebla when the Mexicans defeated the French. Instead we are celebrating a milestone in the construction of the new bicycle.

Look Ma, No Brakes!

We have enough of the bicycle completed and assembled to be able to sit on the frame and coast down a hill, feet in the air, laughing and screaming “Look Ma, No Brakes.” Both Judy and I have taken turns coasting on the bicycle frame. The frame has one seat, two wheels and handlebars. It has no cranks, no chains and no brakes. There are no gears to shift, no pedals to click into and indeed nothing to put your feet on. But it is a time to celebrate our progress.

Judy Gets to Try the New Bicycle

I do have to back up and re-design one part of the bicycle. I was showing a friend the new frame and explaining how the NuVinci hub worked. Part of the demonstration was to get out the shifter parts and hold them up to the hub. Suddenly a glaring oversight became apparent. I had bought and installed some cast steel dropouts to hold the wheel axles. These are really heavy-duty and strong. However, they are too bulky and the shifter assembly will not fit on the hub. I am going to have to disassemble both the front and rear suspension and hack saw a big chunk of the dropout off and grind it much thinner and then braze them back together again.

Judy Solos on the Frame Rail

Oh well two steps forward and one step back.

Trial Fit:

Gary — Mon, 11 Apr 2011 03:25:49 +0000

Today I reached a significant milestone in the design and construction of the new bicycle. I put the major components together this afternoon for a trial fit. There is a photograph of the new bicycle on the blog. The components are the wheels with tires, the front fork, the main frame with a small front sub frame and the rear suspension frame its Fox Vanilla Shock and one seat.
As you can see in this photo there are no cranks or pedals and no steering. There are cranks, chains, brakes and shifters in the boxes. We have been hauling it all around for a year now. The trial fit was to see that the step-over height matched my design and that everything fit properly.

All the Major Pieces Get a Trial Fit

I did discover a problem with the width of the front fork dropouts. I allowed an extra millimeter for shrinkage when brazing. Unfortunately it shrunk three millimeters. It has to be 165 mm wide between the dropouts for a rear wheel to fit. (Fronts are normally 110 mm but my front wheel is driven by the captain.) I hold the dropouts firmly in place when I braze the tubing joints. Everything gets real hot and expands during the operation. The brass cools and the parts shrink back when they get cold. I think I can thin the locking nuts down on both sides of the wheel and get things to fit. Right now I have to use a crow bar to spread the forks enough to get the wheel in. Not a good plan for the roadside tire patching operation.
After placing the new bicycle back in the shop trailer, Judy and I went for a ride on Path, our green dragon recumbent tandem bicycle. There are about five miles of roads in the campground where we are staying near Congress, Arizona. We rode all the roads in camp at least once each and logged a total of six and a half miles. This is our first ride since I was diagnosed with Parkinson’s disease. My balance has been questionable since the first of the year and we have not ridden as much as normal. Today my balance seemed better and we got along very well. Hooray! Just to be sure, however, the new bicycle is designed so either of us can be the captain.
The new bicycle does not have a name yet. We will have to see what his personality is like when we get him all together and go for that first ride. Path may be getting suspicious with the new set of wheels hanging out in the trailer, but so far I don’t think he has a clue that he will be replaced as top dragon.

So long from sunny Arizona

Gary and Judy

Rage Over a Lost Penny

Gary — Sat, 12 Feb 2011 04:26:03 +0000

I guess I know about how Beethoven felt when he wrote the piano rondo, (“Rondo alla ingharese quasi un capriccio in G major, Op. 129”, better known as “Rage over a Lost Penny”.) I have been making little doo-dahs for the new bicycle. I needed a dozen or so braze-on binder bosses and a dozen or so water bottle bosses. What I have been doing on the cold mornings is to get in my trailer with the electric heater. I set up the Smithy Lathe with a steel rod and start turning out bosses. Today I was finishing up some water bottle bosses. They are three eights of an inch in diameter necked down to nine thirty-seconds. They are about five sixteenths of an inch long and are drilled and tapped for a five millimeter bolt. I whack it off with the hack saw and dress it up a bit with a file. It takes me about fifteen minutes to create each one.

Poor Man's CNC Machine, Note Tools Lined Up in Order of Use. Binder Bosses in Foreground

You guessed it. I whacked one off and it spun out of sight behind the lathe. Now there is not much real-estate back there so I should be able to find it. A quick visual inspection revealed that a quite a bit of lathe turnings and other debris had accumulated in that cramped space. I tried getting at it with my fox-tail brush and dust pan but they were simply too big and awkward. I finally found a wall board taping knife and a paint brush that fit perfectly. An hour later I had a nicely cleaned space, but still no sign of the wayward water bottle boss. I got out my magnetic wand and searched under the motor and in all the crevices and still no boss. By this time I could have made about six more of these little suckers, so I gave it up as a lost cause.

Tool Line-Up for Poor Man's CNC

Here are the Binder Boss and Water Bottle Boss Ready to Braze Onto and Into the Bicycle Frame

Path got a nice little tune up today. Earlier this week I removed the front suspension arm and wheel to get accurate measurements of the joint. I need to replicate the joint on the new bicycle. What I discovered is after nearly ten years the bearings were in really bad shape. There was nearly a sixteenth of an inch of radial play in each of the bearings. That means the suspension arm can wobble, tip and veer as I try to steer the bicycle. I bought new bearings and installed them today.

We immediately took Path out for a romp around the island. Wow, what a difference!

Even ordering the bearing turned out to be a challenge. The shaft size is three eighths of an inch and the outer race press fits into a one inch shell. All of the sources had no bearings that fit that specification. A couple nights ago I woke up with a brilliant idea. I would fit the one inch shell and then sleeve the shaft to fit. I couldn’t wait to search the internet the next morning. I searched for a one inch outside diameter ball bearing and to my amazement the first bearing in the list fit a three eighths inch shaft. Not once but each vender had the same sizes when you search by O.D. There must be some logic there somewhere, I just can’t see it.

It is time to wrap this up and ship it off. We are still at the Beachcomber Resort in Lake Havasu City and the weather here in the Sonoran Desert is getting warmer. Today broke into the seventies.

Gary and Judy

First Frame Cut

Gary — Thu, 03 Feb 2011 01:31:03 +0000

We now have the coach cleaned up so it is time to get down to the business of building the new bicycle. I have been picking away around the edges for 20 months now. I have the wheels built, one and a half seats built and a bit of the rear suspension built. I have been toting all of the component parts around in the trailer for almost 12,000 miles. I have drawn and redrawn the plans a half dozen times to incorporate the latest ideas or eliminate some interference or another. It is time to fish or cut bait.

Gary Cuts the First Piece of the Frame

The largest component in the bicycle is the Boom Tube. It is the backbone of the bicycle and it is about seven feet long. The photograph shows me cutting the steel blank from a one and a half inch diameter 4130 chrome-moly steel tube. I cut several pieces to make each of the parts of the Boom Tube and I have been mitering these pieces to fit the Head Tube and front Bottom Bracket. The Head Tube contains the bearings for the front fork to pivot and the Bottom Brackets hold the cranks for the pedals.

Lug is Placed Above the Joint

Lug Placed in Final Postion

The bottom bracket must absorb the stress of the rider’s pedaling. With each crank of the pedals the frame wants to bend right at the joint. To provide extra strength at this point I will lug the joint. I mitered a second piece of tubing that slides over the boom tube. It is only an inch long. The photographs show how the lug is slid onto the Boom Tube first and then the Boom Tube and Bottom Bracket are brazed together. That will all be filed smooth and the lug will be slid down to the Bottom Bracket and it too will be brazed in place. The lug gives more than double the surface area for brazing and creates a nice strong joint.

We are having a bit of the tail end of the big storm raging across the states. Our piece is cold and quite windy. We expect to get freezing conditions tonight so I took in all my water filtration equipment. The Canadian and Midwesterners around the resort just smile when you ask them if they miss all the cold and snow.

Love to all, Gary and Judy

Flying Again

Gary — Mon, 15 Mar 2010 19:56:09 +0000

After eighteen days on “Shank’s Mare,” we are once again flying down the road on “Path,” our recumbent tandem bicycle.

Here is a brief recap. We were in Lake Havasu City and headed for the grocery store with the cargo trailer in tow. I let the front end of the tandem drop off the curb into the crosswalk. I had the brake fairly tight and had one foot on the sidewalk. The left chain-stay on the front suspension broke right at the brake boss. To get back we loaded the tire and the front end of the bicycle in the cargo trailer and walked it home.

I stripped the old parts; the dropouts, the suspension shock, the brake bosses and the pivot assemblies off of the old suspension and proceeded to build a new stronger version. I carefully painted it three coats of green paint and gave it an extra day to dry. I was so proud of my new stronger version until I assembled it on the bicycle. I suddenly remembered why the old version was asymmetrical and had no brace on the right side. The chain needed to go right through where the new stronger braces were placed.

I carefully charted out where the chain needed to be, and with saws and files I removed a section of one brace and removed the other brace entirely. I had to strengthen the one brace with a section of flat iron and braze everything back into place.

Rebuilt Brace

This morning I put it all back together and we rode around the campground loop twice just to see if things are workable. Hooray! Everything is working in perfect harmony. I wasn’t so confident as to paint the piece before assembly, so now I must take it back apart and repaint it.

It doesn’t look like rain for the next few days, so perhaps we will ride the shiny metal version for a few days to celebrate the event.

We have just finished up a week with friends at the Escapee, Chapter 32 Rally at Pass Mountain Regional Park in Apache Junction, Arizona. We hiked many of the park trails including one hike of over nine miles. Now we have moved across the valley to White Tanks Mountain Regional Park just to the west of Surprise, Arizona. The reoccurring rain this winter has created a lush green desert all around us. The Saguaros are fat with water, the Ocotillo cacti are leafing out and the desert plants are starting to bloom.

The Long Walk

Gary — Tue, 09 Mar 2010 21:36:51 +0000

Sometimes things go against you and you have to take a long walk to keep from doing something stupid. Today was one of those days.

From my last blog you know that we broke our bicycle. For the past ten days I have been working to repair the damage by creating a replacement suspension fork for Path. My goal was to create a new part that was stronger and more rigid in all dimensions. I have indeed created a replacement part that achieved those goals. I coated it with three coats of paint and it is a thing of beauty indeed: Aye! in spite of having to use “rattle can” technology.

Ah yes, this does not seem to merit a “long walk.” Well you see there is this thing called the “chain line.” Indeed to transfer power from the pedals to the wheel, the bicycle chain must flow unobstructed from the chain-rings to the cassette. Now I remember why the original design only had a brace on one side!

New suspension looks good, but...

My exceedingly strong and beautiful-to-behold swing arm is of limited usefulness. Primarily down hill where one doesn’t need to pedal. Well actually the chain will traverse nicely from the very largest chain-ring, with 52 teeth to the very smallest cog, 12 teeth. To find the mechanical advantage in this mechanism one must divide the smallest into the largest.

This gives four and a quarter against. That is one turn of the pedals turns the wheel four and a quarter turns.

View of the Chainline

One revolution of the wheel moves you almost 60 inches down the road. Each turn of the pedal takes you over 20 feet down the road. This is fine for downhill racing with a nice wind at your back, but is sure doesn’t get you up the hill. Our normal “granny gear” is about one to one.

My choices are; one, talk Judy into doing all the up hill work and I will cover the downhill legs, or two, take the hack saw to my new suspension and revise it somewhat. I would take a pole on the subject, but I think Judy still has the winning vote.

We have finished up the Bluegrass Festival in Lake Havasu City and we are now attending to a group rally near Mesa, Arizona. In a few days I will get another chance to work on the project. Meanwhile we will still be walking.

Good Day from Gary and Judy and from strong but powerless Path.

P.S. make welcome Herb and Darlene, latest members of our blog family. We spent many hours jamming together over the past few weeks.

Herb and Darlene: If you register you can create a comment and say howdy to all the nice people.

Gary

Basket Case

Gary — Thu, 25 Feb 2010 16:57:09 +0000

History repeats itself occasionally. Today’s story is reminiscent of June 15, 2005 in Medicine Hat Alberta. On that occasion Path had a major catastrophe and we wound up carrying him back about 4 miles. Yesterday again we were about 4 miles from home when Path dropped to his knees again. Judy and I were not injured. However, we were about a mile short of our destination, a grocery store. We had the trailer on behind to carry the load of groceries. We turned around, placed the front wheel in the trailer and rigged the front end of the bicycle so it could ride in the trailer beside the wheel. Same as before it took us a little over an hour to walk back to camp.

Gary and Path on the Long Road Home

Analysis of the failure revealed a stress crack in the suspension right at the brake boss. The crack had finally grown large enough to break straight across when I dropped the front wheel off the curb. We were preparing to cross the street at a crosswalk. Path has been a faithful steed for 13,070 miles since our first ride on February 14, 2002.

I am the basket case, however. Today we are struggling with whether or not to rebuild Path or pull out all the stops on constructing Son-of-Path. Here are the competing plans:

1. I have the steel and parts to rebuild the existing suspension arm. It will take me a week or so to complete. The question is; Will Path become as good as new, or are there other stress cracks under the paint getting ready to fail?
2. I could complete the suspension arm that I have been working on for Son-of-Path and modify Path to use this suspension until we are ready to change to the new bicycle.
3. Should we get the Purple People Eater, our Co-Motion upright tandem out of retirement and use that for the next few months while I continue to build Son-of-Path?
4. We could also buy a couple of used mountain bicycles to get around on while construction continues.
5. We could walk a lot.

Judy and I will be debating these options and setting up a plan over the next few hours. You are all invited to make comments. I can’t seem to imagine life without a bicycle.

Meanwhile we are still hanging out in the state park in Lake Havasu City. We are ready for the next Bluegrass festival to start forming up on Monday. Actually all that picking and grinning cuts in to my shaping and brazing time. How on earth did I ever find time for forty some hours of work in a week.

So long for now, Gary and Judy (and poor injured Path.)

Broken Front Suspension Arm

Closeup of Brake Boss and Broken Chain Stay

One Step Forward:

Gary — Sat, 07 Nov 2009 03:42:24 +0000

“One step forward and two steps back;” That’s what my Dad used to tease me when I complained about the five block walk to school. He lived with his folks near Ewan Washington on a dry land wheat farm. He walked two miles to school and in the winter with drifting snow blowing hard he told me the he would take a step forward and the wind would blow him back two steps. I got suspicious when he told me the only way he got to school at all was to turn around and walk backwards.

Today was to be a big step forward. The first small pieces of the new bicycle brazed together. I jigged the pieces of the rear pivot together; set my fire-watch, Judy; and fired up the torch. It is a difficult join because I am brazing two pieces of ¼ inch steel to a piece of thin wall tubing. You must put all of the heat on the heavy piece and let it flow at the last moment to the tubing. I finished ¾ of the perimeter of the tubing. I than reset the piece in the vice to do the last bit. I applied heat to the heavy part again and the pressure of the vice opened up part of the completed seam, destroying my careful alignment.

I must now hack-saw the tubing off close to the steel parts and grind the brass off the pieces. I will then recreate the tubing and start over.

Afternoon report: I have now cut apart the assembly and filed off the remnants of the tubing thus salvaging my ¼ inch frame pieces. So I am back to where I was before I picked up my torch this morning.

One does get wiser from these experiences. Instead of clamping and holding the piece in the vice I have drilled a ¼ inch hole through the centerline of the 1 inch connecting tube. I will bolt the pieces together until I finish brazing. That way I can turn and work the piece as I need and the vice won’t siphon off all my heat.

I will try again in a day or two, stay tuned, I hope it works better than today.

Brazed Joint Opened Up

Starting to Hacksaw the 1 inch Tubing to Salvage the Cheek Pieces

Rear Suspension, Work Day

Gary — Tue, 03 Nov 2009 03:26:45 +0000

We have moved to Gilroy California and it is once again warm. Today I dug out my entire horde of aircraft steel tubing. When you buy steel there is a substantial minimum order. When I built “Path” I had plenty of steel left over for another complete tandem. The entire horde turned out to be 55 pounds. We have hauled all of this along for five years now

I have the following sizes to work with:

½ inch - 8 ft
5/8 inch - 8 ft
¾ inch - 16 ft
7/8 inch - 2 ft
1 inch - 17 ft
1- 1/8 inch - 7 ft
1- 3/8 inch - 16 ft
1- ½ inch - 16 ft

After completing the inventory I have now cut four pieces of tubing, and the bearing carriers for the rear swing arm suspension. I then created a base board out of 3/8 inch plywood and screwed it to 2×2 frame. A full scale drawing is taped to the center line of the board and I am setting up supports for each component.

Next step is to miter each tube for a perfect fit to its mates. Then each component will be aligned and the assembly brazed together. Here is a photo of the base board and the supports for the dropouts and pivot bracket.

Rear Suspension Supports