Choppers aren't just for grownups, dude! In fact, with the abundance of little kids' bikes at yard sales, scrap yards and dumpsters, it only makes sense that this had to be done. Even brand new, a 12-inch wheel kids bike will only set you back a little more than 50 bucks.
As for learning to ride a chopper, kids just don't seem to know the difference - they wobble around on the bike without a care in the world. Most kids that tried the small choppers that I made, could ride them on the first try. I guess if you're not used to a standard bicycle yet it may even be easier to master a chopper. Old dogs, new tricks, you get the idea.
More cool projects can be found at: http://www.chopzone.com
Step 1: Choose the Donor Bike
Because of the size of the tubing on these bikes, and the fact that the rider will not weight very much, a single tube can be used to extend the frame into a chopper. Notice the oversized down tube on this bike (Photo 1), it will be easy to lengthen this to create a stretched frame chopper.
Step 2: Tear It Down to Its Basic Parts
It sure doesn't take long to break a small bike like this down to the individual bolts (Photo 2). Overall, the entire bike was in good shape, even though it was found under the scrap pile at the dump. I guess these bikes only see a year or two of life due to the speed at which a kid will outgrow a frame this size. For the record, there are seven common bicycle wheel sizes - 12", 14", 16", 20", 24", 26", and 28". Do you think they did this so a kid would need a new bike every year until they stop growing?! Hmmm.
Step 3: Muffler Tubing Stretches the Frame
The down tube and head tube are separated from the frame (Photo 3), and a length of muffler tubing is inserted into the mix. Any thin tubing of 1.25 to 2 inch diameter would work, but this muffler tube was handy in my scrap bin at the time. The head tube will end up almost twice as far away from the seat as it used to be, but some of that distance will be taken up by the extra rake angle forcing the handlebars towards the rider.
Step 4: Weld the Extenstion Tubing
Once the ends of the tubing are ground to fit properly, the extension tubing is welded in place (Photo 4). It should be very easy to ensure alignment, since the end of the top tube and the bottom bracket are both in their original positions. All the joints are fully welded and ground at this point.
Step 5: Determine Proper Height
Fork length and bottom bracket height are the determining factors in head tube angle, so the bike is mocked up at its proper height and the front wheel is positioned where it is desired in the final build (Photo 5). The goal is to ensure that the pedals will not scrape the ground when the bike is finished.
Step 6: Weld the Head Tube
Once the correct head tube angle is figured out, the end of the new top tube can be ground out to form a good joint for welding (Photo 6). It is best to tack weld the head tube in place first only at the sides so that you can check it visually for alignment; hit it slightly with hammer to readjust before welding again if necessary. On my design, the head tube was actually 90 degrees to the top tube, so alignment was easy.
Step 7: Extend the Forks
The original forks will be extended by cutting them off near the top and inserting whatever length of 1-inch thin walled electrical conduit tubing you like. This conduit is the same diameter as the fork tubing, so welding it end to end with the original fork tubing will work out nicely. Cut the original dropouts from the forks as clean as you can, keeping their original shape (Photo 7). Once cut, it's a good idea to grind the dropouts in a vice clamped side by side so that they end up exactly the same size.
Step 8: Extending the Forks
The two lengths of conduit will be inserted into the forks as shown in Photo 8. Put everything in place, and make sure both fork leg extension tubes end up the same length, or your front wheel will not center easily.
Step 9: Bolt Front Dropouts to Wheel
To ease the entire fork building process, bolt the front dropouts to the front wheel as shown in Photo 9, then the dropouts can be welded to the fork extension tubes in the correct position. If you lay both fork tubes on a flat board and do this, the front wheel and dropouts will be centered and aligned on the fork extension tubes. Of course, tack welding everything in place first is always a good idea, then you can give it the visual inspection before welding the entire joint.
Step 10: Weld Extended Forks
Once the forks are tack welded and appear straight, weld the entire joint, and grind it as smooth as possible (Photo 10). Because of the similarity in outer diameters of the original fork tubing and 1 inch conduit, the final product should look like one continuous length of tubing after paint is applied.
Step 11: Check Alignment
Place the forks, bearings and hardware on the bike, and get the front wheel in place (Photo 11). The chopper should be straight, and the bottom bracket should be positioned high enough for adequate ground clearance once the cranks are installed. If all went well, it's just a matter of putting the other components on the bike to complete the build.
Step 12: Chop the Handlebars
To make the original handle bars a little more "choppified", the cross bar that was once used to hold the crash pad was cut (Photo 12). This instantly turns the BMX style handle bars into chopper style handle bars. Grind the leftover metal from the cut area, as it will be sharp.
Step 13: Assemble Before Priming and Painting
I like to assemble the entire bike before painting, just to make sure no other welding or changes are necessary (Photo 13). Little things like fender mounting brackets can wreak havoc on your paint job if you have to weld them in place after the fact. So far, everything seems to be working out perfectly. Paint time.
Step 14: The Final Cool Chopper Needs a Rider
The FireCracker was painted red, of course (Photo 14), and the original blue trimmings were kept, as it accented the bright red quite nicely. A fatter rear tire was also found on my scrap pile, but other than that and the extension tubing, all of the bike is original. Not bad for a few hours work, and 5 bucks for spray paint.
Step 15: Cool Rider Found!
Kids can master a chopper faster than the old boy crowd, maybe because they have not tasted the pavement as much as we have, and the fear factor hasn't been ingrained in them yet. Photo 15 shows Brayden ripping down the laneway on the FireCracker, totally fearless of the ground below!
Step 16: That's One Cool Dude on His New Cool Ride!
Thumbs up, buddy! In another decade or so, this dude's ride will probably have spinner rims, a custom frame, and a price tag comparable to that of a house. Yep, once stung by the chop fever, there is no escape! The young dudes love choppers.
More cool projects can be found at: http://www.chopzone.com