Mountain Lion - Section 1

It's always fun when building a chopper from a complete bicycle to keep some of the original character in the bike. Like one of the other choppers on this compilation, Granny's Nightmare, I will try to keep the theme of the original mountain bike in this chopper, The Mountain Lion. To create a chopper rebellious to the normalcy's of everyday life yet still claim to be worthy of heavy back woods riding, one will need a heavy mountain bike with front suspension. Where does one find a scrap suspension mountain bike? The city dump of course!
 

After digging through the giant scrap metal pile at the local dump, I pulled this somewhat functional bike from the pile (Photo 1). It was in need of a chain, and a bunch of cables, but the heavy steel frame and from suspension forks would be perfect for choppification. The wheels and tires were in really good shape, and I kinda like the color scheme of the bike, so I decided I would re-paint it red and black when completed.

Photo 1 - Steel framed front suspension mountain bike.

All the little bits came apart nicely, and there was no damage to the frame, wheels or bearings (Photo 2). For this chopper, I planned to use all of the parts, so it's a good thing nothing was bent. When you hunt for donor bikes at your local landfill site, you have to get there right before closing, or the "bulldozer man" will turn all the usable bicycle salvage into twisted piles of unrecognizable scrap.

Photo 2 - Mountain bike parts.

I wanted to extend the suspension forks a great deal, but still keep the bike functional, so the frame would have to be extended and the rake increased, or it would become a skyscraper. Since the top tube and down tube were exactly the same diameter, I just cut the head tube and top tube from the frame (Photo 3), so I could reattach it upside down to the down tube.

Photo 3 - Cut the top tube and head tube from the frame.

That was easy! I just inverted the cut section of top tube and butt-welded it to the down tube to create an extendo frame (Photo 4). This modification increased the rake and handle bar to seat distance so that a long set of forks could be used without raising the bottom bracket to ridiculous heights. There is no real trick to welding the two frame pieces together, just try to get them as straight as possible, then grind the welded joint smooth. If you do a good job with the grinder, the tubing will look like one continuous piece when painted.

Photo 4 - Voila - a longer frame!

Wouldn't you know, that chunk of muffler tubing over in my scrap bucket was just the right length and diameter to become the new top tube for the newly extender frame. In order to facilitate welding, and follow the design of the original bike, the tubing is hammered in a little at the ends. This is done because the tubing is much wider than the seat tubing, and it makes the welding job a lot easier. Crushing the ends in a vice also works.

Photo 5 - A chunk of muffler tubing.

Muffler tubing is much like electrical conduit in wall thickness, slightly heavier than bicycle tubing. The tubing I found in my scrap bucket (Photo 6) is about 1.25 inches in diameter, and seems to be about the same diameter and thickness as the original tubing on the frame.

Photo 6 - Muffler tube cut to fit.

As long as the new top tube fits, just start welding it in place. Since there isn't much than can go out of alignment, it's just a matter of getting a clean joint, and welding the tubing all the way around. Photo 7 shows my completed and fully ground frame. On to the next step - the forks.

Photo 7 - The completed extendo frame.

For this chopper to become a worthy beast capable of mowing over anything in its path, it was decided that keeping the front suspension in tact would be a good idea. The front forks were cut just below the crown in order to leave about 1-inch of tubing behind (Photo 8). The reason for this is because I planned on using 1 inch conduit to extend the forks, and by chance, the outer diameter of the original fork leg tubing fits perfectly into the conduit - no alignment necessary!

Photo 8 - Chop those forks in half.

Extending these forks was so easy, I was starting to feel lazy! Just cut two equal lengths of conduit (I used 4 feet each), and jam them into the top of the forks, as shown in Photo 9. Once they were both in place, I laid the unit on a flat surface and weld away. As long as you keep the distance between the fork legs the same all the way down, you will be home free.

Photo 9 - Extending the fork legs.

Now that the top of the forks were welded to the extension tubes, repeat the process with the lower section of the forks. Because the lower half contains the suspension, make sure to leave enough room above the moving part of the forks for travel (Photo 10) - on these cheap mountain bikes, this is not more than 2 inches. Also, weld an inch or so at a time and let the area cool. There are plastic parts inside the sleeve used as bearing surfaces for the sliding part of the fork legs.

Photo 10 - Joining the bottom of the forks.

The welded fork set should be straight as an arrow (Photo 11). Because the original tubing was used as a guide, there is no excuse to have a crooked or warped fork, got it?

Photo 11 - Let your eyes be the judge.

The forks and bearing hardware were installed on the bike (Photo 12). I like to get the forks and wheels on a chopper in order to visualize what might come next. Some of the best ideas are spur of the moment, and if you can visualize the plan in your head, you will save a bundle on paper and pencils.

Photo 12 - Extended forks installed.

For the Mountain Lion, I wanted a seriously padded seat, after all, it would probably be driving over the roofs of cars at intersections and riding over rough terrain like vegetable gardens and flower beds. Of course, I didn't want a seat so huge that it looked as though I tore it from a station wagon either. For this chop, I would make a foam block seat using two pairs of old speed bike forks (Photo 13).

Photo 13 - Some "roady" is missing his fork.

Since the homebrew seat would bolt directly to the frame, I did not want the original seat post clamp, so it was cut down as short a possible (Photo 14).

Photo 14 - Cutting down the seat tube.

One of the spare fork sets will become the base of the seat. Although any small tubing would work, why not use scrap from the bicycle parts bin? The stem is cut from the forks right at the crown, then the legs are bent together by force (Photo 15).

Photo 15 - Forks with stem removed.

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