Mule Packer–the D.I.Y. Travel Bike that Flies Free!

The Mule Packer bike is the simplest method of building your own low-cost demountable travel bike using only common hand tools! You assemble it from half-frames cut from two 1980’s mountain bikes with different diameter steel tubing. You cut the front and rear halves so they overlap to create two sleeve joints–at the seat post and the down tube. (See photos below.) The result is a rugged frame with a rock-solid connection suitable for unsupported travel on the world’s toughest routes, but easily and quickly taken apart for truck, bus or train rides–the best of both worlds!

Peter Marsh on top of Astoria on the first Mule Packer in 2014

 

Mule Packer Essential Features

  1. Built from two first-generation steel mountain bike frames
  2. One is 1.125 “oversize” tubing, the other is 1.25″ “oversize-plus” tubing.
  3. Both connections are sleeves, the simplest, strongest joint possible.
  4. Tools:  a tape measure, bevel gauge, caliper, hack saw and a file.
  5. 100% “failsafe” design that is ridable even without the clamps tightened.
  6. Demounted, it measures 25″ x 26″ x 10″ < 62″ limit for airline luggage. 

NEWS: the prototype Mule Packer (photo above) flew from the USA to Chile in January, 2016 at no charge on United Airlines and took its first long-distance ride on the Carreterra Austral. We covered 500 kms of jarring dirt roads, and another 1000 kms on asphalt. I even broke it down for a few bus rides with no problems. So the Mule Packer is truly tested and ready to go again–anywhere in the world.

How Thinking “Inside the Box” Created a 26″ Wheel Travel-Bike           I was aware that a frame could be professionally hand-built, cut in half, and fitted with the well-known and expensive S & S couplings. But I challenged myself to find a simpler, cheaper and better way to achieve this without welding, brazing or machining. I began by experimenting on  several junkers, cutting them up into “half-frames” with a hack saw in the basement of Bikes & Beyond in Astoria. (They were destined for the scrap heap anyway.)

Upper joint uses long seat post with two clamps to couple front and rear frame halves for 100% secure joint.

After examining the results, I reckoned the best solution was to combine two 1980’s- type mountain bike frames, one frame  from 1.125 “standard oversize” tubing and the other half from 1.25″ “oversize-plus” tubing that would sleeve at the down tube.

They would be joined at the top by retaining the original brazed seat clamps, or using removable seat clamps. The seat post forms a rock-solid connection between the two seat tubes. The upper clamp is easily adjusted to the same width as the lower clamp.

Note: This is not as easy as it sounds! Finding a perfect mate may take time because the seat tube angle usually increases with the frame size. But some different makes and models overlap. The alternative is to have a capable welder re-set the seat clamp on the top tube to the correct angle. The minimum features to ensure a good quality result are the following:

  1. chromo steel
  2. 3″+ difference in frame size
  3. close to identical seat tube angles.
  4. full braze-ons and gear hanger
  5. circular down tube only–oval won’t work!

Mule Packer Travel Bike: D.I.Y. for Low Cost and High Strength

I started off with a Specialized rear half in 1.125″ tubing, so my search continued for a matching front half in 1.25″  tubing. I finally found a Giant frame  at the Community Cycling Center in Portland where they held a weekly scrap bin sale.  Note that you can also have the bigger tubing at the rear, making the rear frame the outer part of the sleeve. And don’t worry about the brands–all these frames were built to last!

I had assumed I would need a shim to make a tight fit on the sleeve joint between the two  down tubes, but they  slid together with a precision fit, like a piston into a cylinder head, as if they were meant to “telescope.” (Left)

The diameter of the top seat clamp was easily reduced to fit  the smaller seatpost (from the narrower rear half frame) and it slid smoothly through to unite both halves. I cleaned up the cuts with a file, sanded and painted the rusty back half. I was pleased to find how solid the coupled frame felt, and built it up with standard “retro”1980’s parts in the summer of 2014.

I made many test-rides on the trails around Astoria, and on the west hills of Portland, including some rough descents, and couldn’t feel any difference at all from a normal frame.  I was absolutely confident that the joints were as strong as a conventional frame and would hold up under long-term hard use. I also proved this is a 100 % “fail-safe” design–ridable even if the clamp bolts loosen or fall out completely!

In 2015, to improve the “packability,” I swapped the old-style alloy crankset for a modern two-piece style that doesn’t require a crank puller. This greatly simplified the packing order, which I perfected using a cut-down cardboard bike box.  However, I still had to build a rigid bike box to protect the wheels from damage while being thrown around by the airline. So I actually spent more time building the box from thin plywood than the frame! Then I  salvaged a telescoping handle and wheels from a worn-out rolling suitcase, strapped it to the box, and rolled it around the block. I weighed it and found I could add a few items and still come in under 50 lbs/24 kilos. Now I was finally ready for my next adventure.

Mule Packer ready to box up--handlebars shown outside package for clarity, they actually go in space between wheels. inside package.

Mule Packer ready to box up–handlebars shown outside package for clarity, they actually go in space between wheels. inside package.

Why is it called the “Mule Packer?” 

  • mule becausit is a cross between two different species (of bike)
  • packer because it packs small enough to ride on a plane–or a mule
  • The name “Mule Packer Bike” is copyright P. Marsh 2014.

How suitable is a 26″ wheel bike? I enjoy touring on good roads with 700c wheels, but 26″ is the maximum tire diameter that falls within the airlines 62″ rule (26″ x 26″ x 10″) and is also the most common and maybe the only size of wheel, tire and tube available outside the developed countries. It’s also stronger, more versatile and great for commuting; so I have built up several other old frames with 26″  slick tires for all-round daily riding. I also use this for testing tires, racks, luggage, handlebars, gear systems etc.

Is this a first in bike design? This page has been up since 2015 and no one has challenged my claim to be the first person to  demonstrate this sleeving principal on the web. If it’s been done before, I can definitely state that I had no knowledge of any previous version. Now, I am explaining the principle for anyone with mechanical skill.

What’s the catch, you ask? To repeat,  you need a good source of old mountain bike frames because  it’s not as easy as it looks to find two frames with identical seat tube angles that will fit together nicely. But remember, you can put the half with the small tubing at the front or the back, which doubles your chances.

The Mule Packer and me at a hostel in Valparaiso, Chile--city of murals.

The Mule Packer and me at a hostel in Valparaiso, Chile–city of murals.

I this appeals to you and you can’t actually figure out the finer points of how it’s done, I’ll be happy to send you a full explanation with photos, sketches and cutting guides to walk you through the process. In return, I request a small donation of $25 to support this web site and my continuing work on “re-cycling.”(Please note “Bike Frame Kit” with  your donation or contact me to let me know that’s what you’re seeking. Alternatively, I may have another bi-frame set that I can sell.

Do I call myself a “frame builder?” Yes, with no reservations. I feel I served a short but demanding apprenticeship and really did “build” my own bike frame– without advanced metalworking skills!  I also achieved a personal goal: inventing, building and riding my own bike on a difficult foreign route!

Mule Packer 2.0 (March 2017)

This pair of half-frames came together nicely in a couple of hours, thanks to my use of electric disc grinders! The result is notable for having a modern design on the Raleigh front half with sloping top tube and very large diameter steel tubing. Again I found this fits precisely over  the oversize+ in the rear triangle without a shim. It should fit me very well and may become my demo model for local rides.

RECOMMENDATIONS FROM BIKE INDUSTRY PROFESSIONALS

A U.S. Olympian 1960 & 1964; member of the road cycling and mountain biking halls of fame, and designer of a very early mountain bike in 1976, had this to say about the Mule Packer: “That is truly the most creative bit of a bicycle mechanic’s work I’ve ever seen.”- Victor Vincente of America,

One of Portland’s top frame builders, and a prize winner at the North American Handmade Bike Show, said this when he saw the Mule Packer: “I would have said that was impossible….but you’ve done it!”  Thomas Ahearne

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 ORIGIN: The inspiration to create the Mule Packer came from my previous visit to Patagonia in 2011, using a folding Bike Friday. I found the limit for me and the bike in 2011 when I rode from Trevelin, Argentina  through the Andes to the whitewater rafting center of Futuleafu, Chile. This route runs along the river valley that forms the only low-level crossing of the Andes. It is over 50 kms of rough dirt road covered with loose rocks–called “ripio” in Spanish. That made progress difficult with a full load, so it took several hours with stops to rest my hands and arms. I realized that this wasn’t an experience I wanted to repeat–ever!

That’s when I began to wonder if it was possible to make a standard 26”-wheel mountain bike fit into a suitcase. With my advancing age, I would welcome the small decrease in rolling resistance and the large reduction in vibration from 62″ tires, enabling me to handle badly maintained roads, gravel, dirt, cobblestones, etc.

Footnote: A little over a century ago, the U.S. Patent Office estimated that about two-thirds of all new patents were bicycle-related. While the figure is no longer quite that high, bikes continue to inspire inventors in a way that few other devices do. You can see this on websites like Kickstarter where  today’s bike-riding inventors present a never-ending stream of bike gadgets they all claim will “enhance your cycling experience.” Well, the Mule Packer isn’t about one of those wacky gizmos, and it needs no batteries or smart phone to make it work!

 

 

 

 

 

 

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One Response to Mule Packer–the D.I.Y. Travel Bike that Flies Free!

  1. Jeremy Kurtti says:

    I had the pleasure of viewing Peter’s handiwork at Bikes & Beyond. Nice job. Very nice indeed.

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