Mountain Bicycle Chopper

This is how to build an extended frame mountain bicycle chopper!

Step 1: Get an Old Mountain Bike

If you have a Murray mountain bike, this works best, but any old mountain bike will do.

This is exactly what the bike i used looked like.

Step 2: Remove Everything From the Frame

Sounds easy enough, but you will have to take off all the equipment from the frame

Step 3: Make a Gameplan

It is wise to make a sketch of your work, and since I did all the trigonometry for you, you can skip this step.

Step 4: Cut Your Forks

Your forks should be cut where it is flat, so cut somewhere in the middle of your forks

I chose 7.5 inches down, but the height may vary on your bike.

Step 5: Forks Cut

This is what your forks should look like cut.

Step 6: Extend Your Forks

Now this is the part where I made the wrong decision.
It wasn't necessarily wrong, but there are better methods to use:
I bought online 2- 36in tubes that were exactly the same as my forks.
I went on to butt welding the tubes to the forks.
The forks hold just fine, but that is because I had a professional weld my forks together.
I would HIGHLY advise not to do what I did if you don't have a pro welder sitting next to you.
The wise way would to be getting tubes that fit AROUND your forks,and just slide your forks into the tubes and weld. Trust me, this will save you time and money. 


(I USED A MEG WELDER TO WELD THIS BIKE)

Step 7: IMPORTANT STEP

After welding your forks together, if you want to have a front brake, weld a piece of metal between the two tubes where you can mount a front brake.
I didn't think about this, and I ended up placing a piece of metal too high for the front brake.
It doesn't make a difference, but you can get more braking power if you do this right.

Step 8: Forks Complete

This is what your forks should look like once you are done.

If you got this far, then great, your only half way done :) .

Step 9: The Hard Part, Frame Time.

This is where things became difficult. I spent 2 months trying to figure out how other people did their mountain chopper bicycle, and of course there were no dimensions or anything.
So, after much research, I found a way much more structurally sound and easier to do.

Step 10: Cut Your Frame

The first step is to cut your frame.

Preferably cut your frame 2 inches away from the top tube and 4 or 3 inches away from your bottom tube.

Step 11: Cut Goosneck

This is what your cuts should look like

Step 12: Cut Off the Top Tube

Now cut the top tube completely off. Save the tube for later.

Step 13: The Bottom Tube

Here is where I differ from the Mountain Lion Chopper bicycle. Instead of welding a tube to the already cut bottom tube; were going to get a larger diameter tube and slide it over the cut bottom tube.

I figured out that the other people who extended their frame did it exactly 2X their bottom tube. So 16in X 2=32., Buy a new tube which will just slide over you original bottom tube, and make sure the new tube is 30 inches. This method is more safe, and is easier to do.

TO MAKE THE BIKE LESS HEAVY, CUT A LITTLE MORE OF THE BOTTOM TUBE UNTIL THERE IS AROUND 6-10INCHES LEFT

*notes*

I used a Meg Welder to weld the bike.

You must cut off the little dongles which held the gearing system from the underside of your bottom tube.

Step 14: Goose Neck Modifications.

Remember your goose-neck? now we're going to do some modifications to it.

Cut off the top tube part from your goose-neck. Be careful not to bite into the goose-neck while grinding it.

You can discard the top tube part or save it for later.

Step 15: Attach the Goose-neck to the Frame

Now that your frame and goose-neck is ready. attach both together.

You should grind off the new bottom tube of your frame into a U shape so that it will accept the goose-neck.

The two pieces should fit perpendicularly. 

*Optional * grind a "U" shape to the new bottom tube so that the goose-neck will fit properly.

*NOTE*

If the goose-neck is not fitting at a 90* angle to the bottom tube, cut the bottom tube off the goose-neck,

and quickly weld it back on @ a 90* angle.

Step 16: Check Up

Your frame should now look like this.

Step 17: Now Weld a New Top Tube

Now that the bottom tube and goose-neck is complete, weld the top tube.

The top tube i bought was 30 inches, grinded down it was around 28 inches.

MAKE SURE YOU GRIND THE TOP TUBE PROPERLY, OR YOU WILL HAVE HUGE HEADACHES LATER ON!

Step 18: Spray Painting.

To spray paint.

Get some high powered PAINT SRIPPER from any hardware store.

Apply the stripper to your bike, wait some time, and rub the paint off with some steel wool.

Wipe off all of the paint, then apply some MINERAL SPIRITS or PAINT THINNER. This will remove all the grime.

Buy some AUTOMOBILE PRIMER and apply to your bike. Apply about 2 coats.

Buy whatever color you want, and apply 3 to 4 coats. FOLLOW YOUR SPRAY PAINT BOTTLE INSTRUCTIONS!

After the spray paint has dried, apply ENAMEL FINISH CLEAR COAT . Apply 2 coats.

Step 19: You're DONE!

Your chopper bike is complete. All you have to do now is to go to a bike shop and have them re size your chain onto whatever sprocket

place you want, and to re do your brakes.

For the chain I chose The largest sprocket on the front part (where the pedals are) and the third counting from the smallest sprocket on your back wheel. 

The back brake and the front brake can be zip tied back on.