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.

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

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

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

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

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

Rear Suspension Supports

Over the past three weeks I have been concentrating on collecting the components needed to assemble the new bicycle. Some of these parts have been the wheel rims and the NuVinci hubs. I tried to purchase spokes for the new wheels and ran into a size problem. The NuVinci hubs are rather large in diameter and consequently the spokes only needed to be 149 mm long. That is about 5 and 7/8 inches long. My solution was to buy a Hozan Spoke Threader and make my own spokes. You cut your spokes to the exact length and the machine rolls a perfect thread at the end of the spoke. I built the first wheel this afternoon using the wheel building instructions on Sheldon Brown’s wonderful legacy site maintained by Harris Cyclery. Sheldon died February 4, 2008 according to a biography story on Wikipedia. The web site at http://sheldonbrown.com/home.html is a wealth of information for bicyclists and bicycle mechanics. I followed the step by step instructions and my wheel has turned out perfect. I will have to repeat the process again tomorrow.

Here are some photographs of the spoke threader and the new wheel.

Gary Dinsmore

Rolling Threads on a New 149 mm Spoke

NuVinci Hub, Spokes and Sun Rhyno Lite Rim

Completed Wheel ready for Truing

I finally stripped all but the essential components away and came up with a simple device consisting of a standard eight speed freehub and a BMX freewheel. The freehub mounts hub-side outward on the motor jackshaft and the freewheel is slotted to fit onto the splines of the free hub. A couple of the original freehub cassette gears are slipped back onto the freehub and the locknut cinched down.

Peddle power is input through the BMX freewheel. Since the freehub is mounted backwards it goes into freewheel mode as soon as you start peddling. The splines of the freehub drive the cogs and that power is output to the wheel. When the motor starts to turn the inner hub of the freehub the dogs engage the freehub drum and thus also output power to the wheel.

Either power source can drive the wheel independently of the other power source. Either power source can coast at will.

The Shimano® BMX Freewheel that I chose had a hardened steel inner raceway. I created a jig for my lathe/milling machine and needed my hardest carbide tipped tools to bore the freewheel to the diameter of the drum of the Deore® Freehub. I then set up an indexing table and cut the nine slots to fit the splines with the milling machine and a Dremel® diamond coated bit. After sixty hours of careful, tedious work I had a perfect slip fit.

I am now ready to order the rest of the components. Stay tuned for further updates.

Gary Dinsmore

Gary Rockin to Bluegrass and Milling Splines

Closeup of the Spline Grinding Operation

Power Distribution Hub

This blog will have its separate mailing list, and you may opt out by simply dropping me an e-mail. Instead of the blog coming as an e-mail with full text, I will simply drop you a note telling you there is a new update. This will include the following link:

Son of Path

This will take you to the menu page showing the full list of topics available. That way if you are busy you can put off reading the latest and catch up next time a notice is sent. Two topics are available at this time; “Inspiration,” and “Power Distribution Hub.”

I invite you to follow along and even comment on my design. Just remember to format any critical review of my work in soft, soothing, weasel words. I hold the keys to the master mailing list!

Let the grand adventure begin,

Gary Dinsmore

First: “Path” is the name given to Dinsey Mark II. This name was derived from Anne McCaffrey’s “Dragon Riders of Pern,” a fantasy/Sci.Fi. series about a mythical planet with mythical dragons with telepathic and telekinetic powers. “Path” was a Green Dragon ridden by Mirrim in the series.

The Terra based “Path” is ridden by Gary and Judy Dinsmore and was a participant in the 2009 Oregon Human Powered Challenge May 23 through May 25, 2009 at Portland International Raceway. At this time “Path” had accumulated 12, 121 miles in about eight years of riding. Periodically I would meditate over what the next version of the Dinsey series of bicycles might look like and what improvements it might have.

On May 25th I volunteered at the electric assisted bicycle races and watched participant, Josh Kerson, put his state-of-the-art electric assist bicycle through its paces. Suddenly I knew what the Mark III needed. I paid Josh $100 for technical specifications of the drive train for his bicycle, and soon I was developing the design for the new bicycle in Delta Cad. By June 2nd I had a workable “As-Built” drawing of Dinsey Mark II and I started on the design drawing for Dinsey Mark III on June 5th.

Following are some photos of Dinsey Mark II, “Path,” and some of his adventures through the years.

Check back occasionally for updates.

Gary Dinsmore

Path, Gary and Judy Strut Their Stuff at the 2006 Oregon Human Powered Challenge

Riding Path is a Little Tricky, Mark and Cody Try Their Skills

Family Photo

Riding Formation With Dr. Bill and Diane Patterson

Path Gets Closeup and Personal with a Texas Alligator

The heart of the electric boost system has to be a device to accept power from either the pedals or from the motor or from both at the same time. I knew it could be done because I saw it working at the Oregon Human Power Challenge. I twisted the problem around in my mind and scribbled ideas on paper for a long time. I wanted it to be made out of off-the-shelf bicycle parts. I made a couple trips to Citybike Workers Coop at 19th and Ancany in Portland. This group salvages parts from discarded bicycles and puts the best parts together to make saleable bicycles. They also have bins and bins of bicycle parts that you can rummage through and try unusual combinations. I selected a couple rear wheel drive components, (a Shimano Deore Freehub and a BMX Freewheel), and brought them home. After a week of turning and milling the pieces on my lathe I can now slide them together in a unique new Power Distribution Hub. This is the first tangible piece of the new bicycle. See photos below.

I am now ready to purchase a motor and gearbox. The specification for the electric stoker drive system is this.

We also picked up materials to create a seat for Judy. I created one earlier for me. It is made of half inch poly-foam, covered with Aramid fabric and Epoxy resin. Aramid fiber, or Kevlar, is what bullet-proof vests are made of, so it ought to be a bullet-proof seat. Stay tuned for a blog on a FRP lay-up episode. It ought to be a gooey sticky mess.

We are still in Hillsboro for a few more days. Then we plan to take our sailboat, Regal Jug, up to Anacortes, Washington for a couple weeks of sailing adventure. Last time we did this in 2006 we put a new tongue in the boat trailer. See (under construction – link goes here)

For now, we send our love and bid you all adieu.

Gary and Judy

Gary Cutting Splines and Rockin

Closeup: Grinding Splines in the Freewheel

Two Views of the Power Distribution Hub