Subscribe to Atomic Zombie News


After Burner Chopwork Orange Firecracker Stinger Wizard Lion Granny's Nightmare Tour Carnage SkyWalker

Bike Hacking (aka "Bicycle Autopsy") - Section 2

Section 1   | Section 2   |   Section 3   |   Section 4

Photo 11 - Loosening the gooseneck bolt.

If you take this bolt out all the way and try to force out the neck, it wont budge, even with a large hammer (I tried this once). The reason for this is the wedge shaped nut at the end of this bolt. As the bolt tightens up, the bolt gets wedged against the side of the fork tube, holding the neck firmly in place.

Once the bolt is out about half-an-inch, tap it down with a hammer so it is again flush with the top where it started. Now you should be able to turn the neck back and forth until it comes out of the fork tube. If the bike is rusty, this may take some work, but remember not to take this bolt all the way out.

As shown in Photo 12, the wedge-shaped nut only needs to push down half an inch or so in order to release the force against the fork tube. If the bike is in really bad shape, you may need to secure the forks and put a lot of effort into cranking the handle bars back and forth until they come all the way up. Always use the hammer as a very last resort, but do whatever it takes to win!

Photo 12 - Gooseneck bolt and locking nut..

To remove the brakes, undo the small lock nut on the back side of both brakes, as seen in Photo 13. The front and rear brakes are the same, so the operation will be identical for each. 

Photo 13 - Removing the brakes.

If there is a lot of rust, you will need to keep the nut on the other side from turning. Once the brakes are off the frame, make sure they still work by pressing them together. If they are bent or badly rusted, it is recommended that you find a better pair, rather than finding out at the last minute that they have failed.

The rear derailleur is usually held to the frame by the wheel nut and one small bolt for alignment with the rear dropout. It is this alignment nut that will be holding it on, since the wheel is no longer attached to the bike (Photo 14). Just turn the bolt a few turns and the derailleur will fall right out.

Photo 14 - Removing the rear derailleur from the frame.

Some better quality bikes have the derailleur mounted directly to the frame using a special drop out. If this is the case, leave it with that frame it will not work on any other. Once the derailleur has been removed, inspect the unit for spring tension, and spin the little plastic wheels to make sure none of the teeth are missing. Unwrap anything that may be tangled around the axels, impeding their movement.

If you have not yet removed the chain, take one of the small wheels off the derailleur by removing the bolt that holds it in place, and then put it back together after the chain has passed through the opening.

The front derailleur is the last bit of small hardware that needs to be removed from your soon-to-be bare frame. Most of these are clamped to the frame with a small bolt.

This bolt needs to be removed all the way in order to allow the clamp to let go of the frame tube (Photo 15).

Photo 15 - Removing the front derailleur from the frame.

Once open, the unit should slip right off by spreading apart the two halves of the clamp. If your chain is still connected, just remove the small bolt at the back of the derailleur, and slide the chain through the opening. If your derailleurs are heavily rusted, drop them in a bucket of Varsol or some other metal cleaning agent. Check for bent arms and seized springs as well.

The seat and seat post are the next to go. This job is either going to be really easy, or really hard depending on how much rust is in between the post and frame.

Leave the seat on for now. This is what you are going to hang on to as you twist the post out. Remove the bolt from the clamp on the frame and slightly spread it apart with a flat head screwdriver, as seen in Photo 16. At this stage, you should be able to hold down the frame and twist the seat and post out of the frame. This may take a lot of effort and some time if it is a long seat post, or full of rust. If it seems to be very stuck with no movement at all, it may be time for the vice grips or pipe wrench, and even then, it may be a chore to remove it.

Photo 16 - Loosening the seat post clamp.

If all of this fails, remove the seat and crush the top of the post in a large bench mounted vice and try to crank it out by holding on the frame. If this still fails to loosen the post, you are on your own. Get a large hammer!

Removal of the forks is straight forward, but you will need a large adjustable wrench, or pipe wrench. Always use an adjustable first, as it will not leave teeth marks in the soft metal parts. All threads on forks are right-handed, so turn the top nut counter-clockwise until it is completely off (Photo 17).

Photo 17 - Remove the top nut to begin disassembling the forks.

Under the first nut, there will usually be a non-threaded ring with a notch in it. This ring will lift right off. The next ring is the top of the bearing race, and this will also unscrew, allowing the forks to be removed from the head tube (Photo 18). Collect the rings and bearings, and store them in a safe place. If all the bearings fall all over the floor, this means the ring that holds them is cracked or rusted away, so dont bother trying to collect them all this bearing set is finished.

When the forks are removed, inspect them for cracks and bends. Check the threads and drop outs to make sure there is no major damage. If you have trouble removing the second ring, it may be because the small notch that stops it from turning has been forced out of the hole and into the fork threads.

This is fairly common, and can be easily fixed by grasping the ring with vice grips and carefully turning it until it goes back into place. Once in place, the ring should easily lift out without force.
A reflector mount that has been forced out of place could also be responsible for damaging the fork threads, but as long as the majority of threads are still good, the fork set will be fine. If all the threads are gone, the forks will only be used as parts for other projects. You dont want to lose a front wheel on a ride.

Photo 18 - Cutting the legs from the fork stem.

Now you are down to the last and most complex part the crank set. First, you need to take both pedals off. This may be the toughest part to do if rust has eaten your bike. You will need an open ended fixed wrench, usually 5/8-inch, most likely a good hammer and possibly even a blow torch. 

The most important thing to remember is that the left pedal (opposite the chain ring) is a left-hand thread. If you want to loosen it, you turn it clockwise, as if you are tightening it. A lot of pedals are stamped R and L on the inside (Photo 19), just in case you forget which one is the oddball.

Now that you know which way to turn the wrench, give it a try. If your bike is clean and fairly free of rust, it may just come right out, but this is not usually the case. In fact, I have had to cut several crank arms right off with a grinder, even after several attempts at heating it red hot and hammering on the wrench.

You may want to keep a good stock of 5/8-inch wrenches around if you plan on taking a lot of old rusty bikes apart. You will almost always have to bang on the wrench with a hammer, and a lot of the time, you will snap one end of the wrench. No kidding! Hopefully, your pedals came off with ease, but if not, its time for the heavy artillery.

Photo 19 - Pedals have a left and right side, as shown in this picture.

Get your biggest hammer and bang the wrench in the proper direction (Photo 20). Remember, right side = right threads, left side = reverse threads. If the pedal will not budge, you can apply some heat using a propane blowtorch or welding torch. Heat up the area around the pedal, not the pedal itself. Heat makes metal expand, so this may loosen the grip on the pedal threads.

If your pedal is plastic, it will probably melt during this operation, but this cannot be avoided, as you need a lot of heat for this to work. Ten solid minutes with the torch is about right. If all of your attempts fail, you may end up cutting of the crank arm with a grinder, but that is still better than nothing. The frame and chain ring will still be in tact.

Photo 20 - Using a wrench to remove a pedal.

Now that youve removed the pedals, its time to pull the crank set from the bottom bracket (the ring on the frame that holds the bearings and cups). There are two types of crank sets one-piece and three-piece (Photo 21). One-piece crank sets are common on BMX type bikes and cheaper hardware store bikes. They have a continuous S shaped crank arm made of solid steel. This type of crank is good for budget projects or projects in which weight is not a consideration.

As you can see in Photo 21, the bottom bracket for the one-piece crank (right) is quite a bit larger than the three-piece (left). Also, the three-piece crank bracket is threaded on both sides, while the one-piece crank bracket has no threads at all. 

Photo 21 - A three-piece crank (left) and one-piece crank (right).

Three-piece crank sets are found on racing bikes and bikes of medium to high quality. There is an axel with squared sides connecting the cranks on each side of the bike. The square sides of the axel are slightly tapered, so as the end nut is tightened, the crank arms get wedged on very tightly. The axle is made of hardened steel, and the crank arms are made of steel or aluminum. This type of crank is good for projects requiring light-weight, precision and high gear ratios. The first type of crank we will remove is the typical three-chain ring one-piece setup. The nice thing about removing this crank set is that only two bolts hold it together.

Before you try to remove the crank set, make sure the left side pedal has been taken out, or the rings will not slide off. If you cant get the pedal out, its time to get out the grinder and cut the arm off or you will never be able to remove the crank set. Find a large wrench, and turn the large nut clockwise (another backwards thread). This is shown in Photo 22. It should come off with little effort unless you tried to turn it the wrong way.

Photo 22 - Removing the locking nut from a one-piece crank set (reversed thread).

Underneath is a ring or washer, and it should lift right out. If it is stuck, it may need to be turned until the small notch is aligned into the small keyway in the threads. Once the washer is off, there is only the bearing race left, and it may come off just by pushing it with your fingers.

Dont forget, backwards threads here, so turn it like youre trying to make it tighter. If this ring seems to be a little stuck, find a punch or old screwdriver and place it in one of the slots then tap it with a hammer, as shown in Photo 23. Once you have it moving a little, it should easily come all the way off.

Photo 23 - Tap a screwdriver into the slot located on the ring in a clockwise direction.

Section 1   | Section 2   |   Section 3   |   Section 4


build overkill chopper
























All content copyright 2003-2009. All rights reserved.