Friday, May 21, 2010

Granny's Nightmare Bike Chopper DIY - Part 2

Continued from yesterday...

The un-squished fork tubing was cut to fit in place as a new main tube (Photo 15), and the leftover end was welded as a gusset where the lug stub was left from the original top tube and seat tube. This little curve on the top tube gave the frame a stylish look, and would be the basis for a gas tank style gusset later on in the build.

Photo 15 - The new frame - all forked up!

Now that the frame has been modified, place the bottom bracket about 6 inches lower than it was before (Photo 16). Although the frame is still tall and laid back, this would work well for what I had envisioned. Be careful with the forks at this point, without the top of the triple tree, they would not take much weight. Dude, don't sit on the bike yet!

Photo 16 - The slightly lower frame.

I found an old cardboard box that contained bicycle safety brochures, and promptly emptied its contents into the garbage can - so I could salvage the empty box. A cool looking gusset was cut from the cardboard as shown in Photo 17, and this was traced onto some scrap sheet steel.

Photo 17 - Template for a stylish gusset.

The gusset is cut from the steel using a worn out cut-off disc on the angle grinder (Photo 18). Although a jig saw with a metal blade is best when curves are involved, this method is much faster if the curve is only slight and you have a worn out wheel like I did.

Photo 18 - Cutting the gusset pattern.


To form the top of the triple tree fork, 2 1/2 inch nuts will be welded into the ends of each fork leg, and a plate will be secured to this by a bolt. Any nut and bolt that will fit into the conduit will work (Photo 19).

Photo 19 - Nuts and bolts for the top of the triple tree.

Weld both nuts flush into the ends of the fork legs as shown in Photo 20. The closer to center you can get them, the better. If the nuts a quite a bit smaller than the inside diameter of the tube, just weld as much as you can, making sure they are both facing the same side of the tube and centered.

Photo 20 - Nuts welded into the fork legs.

The fork will use the conventional triple tree with a top plate bolted to the top of the fork legs, but with a slight difference - it will include the gooseneck as part of the plate. Rather than making a single plate and then fastening a handle bar clamp to it, I decided to use two smaller plates that will fasten directly to a gooseneck. This way, the original bicycle parts, including the handlebars could be used.

I started by cutting a few inches of 1.5 inch flat bar as shown in Photo 21. When bolted to the nuts that are welded into the fork tube, these plates will form a cap between the gooseneck and the fork tops as will be seen in the next few steps.


Photo 21 - Two plates form the top of the triple tree.

The best way to ensure alignment when welding the triple tree plates and gooseneck is to bolt the two plates as shown in Photo 22; this is how they will be in the final design. The two plates should be aligned as if they were one single plate. The round area ground away at the ends of each plate will form a joint with the steel gooseneck.

Photo 22 - Setting up for welding.

Once everything is setup, all you have to do is place the gooseneck into the fork stem, and weld the 2 plates in place. It's best to make a few solid tack welds, then check it all over, being careful not to hit the fork threads with the welding rod. Once tacked in place, it will look like it does Photo 23.

Photo 23 - Weld the plates and gooseneck.

Once the front forks are completely welded and ground, they can be installed onto the chopper (Photo 24). Now the frame can take the weight of a rider - of course, you may want to install a seat first.

Photo 24 - installation of the front forks.

Options for a seat on this chopper are abundant, but what I was looking for was something that would fit the theme of the original granny bike, of course, it had to be butchered into something evil at the same time. Rather than mounting the seat in its natural position, I decided that it should go as close to the rear wheel as possible, putting it just behind the seat tube. To accomplish this silly feat, I welded the seat clamp directly to the plate over the rear wheel (Photo 25).

Photo 25 - Welding a seat clamp just above the rear wheel.

Once I reinstalled the super fat spring seat, it was almost sitting on the rear tire (Photo 26). The nose of the seat covered up the original seat post hole, and this really looked good - almost planned! We are now 30 seconds from the first test crash!

Photo 26 - Now, that seat is low!

Once I rode around the block a few times making sure everything was good, I stripped the bike right back down and painted it using the original deep blue color (Photo 27). I buffed up the chrome parts with some steel wool, and put the bike back together, and damn it dog, it sure looked cool!


Photo 27 - Granny's Nightmare completed.

Yep, Granny's Nightmare really worked out nice! I even reversed the front fender just to add some more wackiness to the bike, but everything looked great. The front chain ring was replaced with a huge chrome unit from an exercise bike, but other than that and some fresh tires, the whole deal was made from the original granny bike. Told you it could be done!

Photo 28 - Where is my bike, young man?

Besides one small incident where the seat almost fell off and started rubbing on the rear wheel, all went well with Kathy's first test ride (was that my fault for not tightening the bolts?). The bike rode well, did not rattle, and felt pretty comfortable considering where the seat was placed.

Photo 29 - KoolKat poses it up with the chop.

The moral of this story - never say a bike cannot be chopped. When you find something in the dumpster, don't think, "Hey, look at that scrap." Instead think, "Dude, this thing will make a sick chop." In fact, just about any thing made of steel can be used for parts. See that old blender? Yeah, I can use that! Granny's Nightmare is a prime example of what can be done by simply modifying what you have and using your twisted imagination to put vision into reality. Now I better go and hide the chopper before granny gets home from Bingo.


Photo 30 - Back from the dead - Granny's Nightmare lives!




More free DIY choppers