Introduction: Atomic Zombie's Granny's Nightmare Bicycle Chopper

Picture of Atomic Zombie's Granny's Nightmare Bicycle Chopper

You know what really irritates me? I drive all the way out to the dump, pay my five bucks to get in, and the only bikes laying around are those granny bikes from the late 1970's. Dog, what's the deal? I need some new parts!

Ok, enough whining, it's payback time. A real chopper artist can chop any bike, even this crusty old codger cruiser. In fact, the more I looked at the bike, the more I thought it would be a sweet ride. Check out all that chrome, look at that long spindly frame, yeah, I could make this happen...

Normally, I do not even bother with these frames because of their "lugged" construction. Lugged frames are not really welded at the head tube and bottom bracket, they are press fit and brazed. Because of this, you cannot really salvage the head tube or the bottom bracket, and this makes the frame useless for parts normally. Even the rims are those goofy 27-inch size, too big for a mountain bike tire. Because I was planning to hack this granny cruiser into something evil, I would be keeping most of the frame in one piece, so the project was still doable.

"Turn down that devil music, you crazy kids!" I could hear the bike talking to me. I thought I'd better rip it all apart before I start wearing a helmet and worrying about brakes! Photo 1 shows the old fashioned bike before hacking. These styles were easy to find at the dump or at yard sales.

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Step 1: Reduced Back to a Pile of Parts.

Picture of Reduced Back to a Pile of Parts.

Here is the donor bike, taken apart for chopping. Even though this bike is older than time itself, it came apart very easily, and the chrome parts had only slight surface rust - easy to clean with steel wool. I will be using all of the original bike, as the theme for this chop will be Granny's Nightmare!

Step 2: Amputate Fork Legs.

Picture of Amputate Fork Legs.

This chopper will have long forks and a slightly modified frame when completed. I did not want to change the bike too much to keep some of its original look - the idea is to make it radical yet show its roots. This photo shows the original forks with both legs amputated right at the crown. It should be easy to build a triple tree from these forks as they are made from heavy mild steel. Back in those days, they knew how to build a bike, not like these young "whipper-snappers" today, sonny.

Step 3: Cut the Ends of the Forks, But Save the Legs.

Picture of Cut the Ends of the Forks, But Save the Legs.

I used the original fork dropouts, so they were cut leaving enough meat to weld to the new fork legs. Save the original fork legs, though. With those nice curves, it should be easy to integrate them back into the frame for a unique and classy look. Both dropouts should be cut as close to the same length as possible in order to ensure wheel alignment.

Step 4: A Pair of 4-foot Long Conduit Tubes.

Picture of A Pair of 4-foot Long Conduit Tubes.

Since the long forks are the focus of the bike, and the frame adjustments will be based upon them, they are made first. I started with a pair of 4 foot long 1 inch thin walled conduit lengths as shown here. Four feet is plenty long, and if I made them much longer, radical frame manipulation would be necessary in order to prevent the "instant wheelie" effect.

Step 5: Grind the Edges of the Fork Crown.

Picture of Grind the Edges of the Fork Crown.

The original fork crown is used as the base of the triple tree. The new fork leg extension tubing will be welded directly to the ends of the crown, so it should be ground slightly to allow for easy welding. Do not take too much metal out, just enough to make a good weld that will cover 1/3 or more of the new tubing's diameter. If you ground too much out, the fork legs will be too narrow for a front wheel, and major warping will occur to the conduit while welding.

Step 6: Tack New Fork Legs in Place.

Picture of Tack New Fork Legs in Place.

Once both fork crowns are ground out, and both fork leg extension tubes are exactly the same length, lay the unit on a flat surface and tack weld both fork legs into place as shown here. Use only one solid tack weld per leg, as you want to be able to align the tubes as the front dropouts are positioned in the next few steps.

Step 7: Bolt the Dropouts to the Front Hub.

Picture of Bolt the Dropouts to the Front Hub.

To get the dropouts aligned in the proper place at the ends of the new fork legs, first bolt them to a front wheel as shown here. They should be secured tightly and both at the same horizontal angle. Also, make sure that the flattened end that holds the axel is not bent. If it is, pull it straight with a pair of pliers. The distance between the dropouts is usually 5.5 inches for a front wheel. These old bikes may be even less.

Step 8: Weld the Dropouts to the Fork Legs.

Picture of Weld the Dropouts to the Fork Legs.

With the fork legs tack welded to the fork crown, and the entire unit laying on a flat surface, place the dropouts onto the fork legs as shown here. First tack weld the dropouts in place, then check alignment visually by looking at the unit from all angles, especially lengthwise. If there is any misalignment, it will be easy to correct at this point with a small hammer. If you are satisfied with alignment, weld all of the fork starting with the dropouts and finishing with the cork crown and legs. Check alignment along the way as you weld.

Step 9: Adjust Height of Bottom Bracket.

Picture of Adjust Height of Bottom Bracket.

Once the forks are solidly welded, place them into the frame to have a look at what you have so far. Most likely, the bike will seem to lean back too far, and the bottom bracket will be very high. Because of the extreme fork length, the frame has been pulled backwards creating the "skyscraper" style chopper. Although the bike would be ridable in this configuration, and it may indeed suit your style, I decided to lower the bottom bracket a few inches by making a small mod to the frame. Since I planned to remove the top tube and convert the frame from a girl's frame, this wasn't a big deal.

Step 10: Remove the Top Tube.

Picture of Remove the Top Tube.

The top tube is cut from the frame right at the thick part of the lugs on both the head tube and seat tube as shown here. The frame is no longer a girl's frame, in fact it is no longer a frame at all, as it would not even hold up to a child's weight like this. I did not cut flush with the tubing due to the lugged frame construction, as this would make a huge mess. I planned to use the thicker part of the lugs to my advantage, as you will soon see next.

Step 11: Take a Bite Out of Your Bike.

Picture of Take a Bite Out of Your Bike.

A rather lazy way to change the angle of a welded tube is to slice a thin pie shaped wedge out of one side, then bend the tube towards that side to fill the gap. As shown here, I hack sawed a pie shaped cut into the base of the down tube so it could be bent upwards, reducing the height of the bike. Mild steel is very forgiving, and the bending process will not weaken the metal. After the gap is filled with weld metal, it will actually be stronger than when I started.

Step 12: Fill the Gap on the Re-adjusted Down Tube.

Picture of Fill the Gap on the Re-adjusted Down Tube.

Once the down tube was bent upwards to close the gap (easy wasn't it?), the area was welded solid as shown in here. If you made your wedge shaped cut even on both sides of the tube, then the tube will move in perfect alignment with the rest of the frame.

Step 13: "Un-squish" the Fork Tube to Make It Round.

Picture of "Un-squish" the Fork Tube to Make It Round.

I thought it would be cool to use only the original bicycle tubing to make this chopper, and since I had a pair of fork legs from the original bike, I decided to use them to make a nice curved top tube. The fork tubing is actually round tubing that has been squished into an oblong shape. To merge it into the frame, I "un-squished" it in the vice, welded the forks together so I would have a piece long enough to become the new top tube, and a bit left over to fill in the ugly gap on the lower lug.

Step 14: The New Frame - All Forked Up!

Picture of The New Frame - All Forked Up!

The un-squished fork tubing was cut to fit in place as a new main tube, 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.

Step 15: Slightly Lower the Frame.

Picture of Slightly Lower the Frame.

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

Step 16: Make a Template for a Stylish Gusset.

Picture of Make a Template for a Stylish Gusset.

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

Step 17: Cut the Gusset Pattern.

Picture of Cut the Gusset Pattern.

The gusset is cut from the steel using a worn out cut-off disc on the angle grinder. 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.

Step 18: Nuts and Bolts for the Top of the Triple Tree.

Picture of Nuts and Bolts for the Top of the Triple Tree.

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.

Step 19: Weld Nuts Into the Fork Legs.

Picture of Weld Nuts Into the Fork Legs.

Weld both nuts flush into the ends of the fork legs as shown here. The closer to center you can get them, the better. If the nuts are 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.

Step 20: Two Plates Form the Top of the Triple Tree.

Picture of Two Plates Form the Top of the Triple Tree.

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 makeg 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.

Step 21: Set Up for Welding.

Picture of Set Up for Welding.

The best way to ensure alignment when welding the triple tree plates and gooseneck is to bolt the two plates as shown here; 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.

Step 22: Weld the Plates and Gooseneck.

Picture of Weld the Plates and Gooseneck.

Once everything is setup, all you have to do is place the gooseneck into the fork stem, and weld the two 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 here.

Step 23: Install the Front Forks.

Picture of Install the Front Forks.

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

Step 24: Weld a Seat Clamp Just Above the Rear Wheel.

Picture of Weld a Seat Clamp Just Above the Rear Wheel.

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.

Step 25: Now, That Seat Is Low!

Picture of Now, That Seat Is Low!

Once I re-installed the super fat spring seat, it was almost sitting on the rear tire. 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!

Step 26: Granny's Nightmare Completed.

Picture of Granny's Nightmare Completed.

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

Step 27: Where Is My Bike, Young Man?

Picture of Where Is My Bike, Young Man?

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!

Step 28: KoolKat Poses It Up With the Chop.

Picture of KoolKat Poses It Up With the Chop.

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.

Step 29: Back From the Dead - Granny's Nightmare Lives!

Picture of Back From the Dead - Granny's Nightmare Lives!

The moral of this story - never say that 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.

More cool projects can be found at: and


DRTMNDSK (author)2013-05-23


amcayanan (author)2013-04-24


Mr.Sanchez (author)2011-02-15

Thnks Man you were My inspiration...behold my Humble copy of your Work: I Give you " La Patrullera.a.k.a The trooper.

onrust (author)Mr.Sanchez2013-02-17

Nice stuff. Check out my forum group:

xd12c (author)2010-05-25

Try IMC metal Conduit.

heathbar64 (author)2010-05-25

 Sweet bike! kinda inspires me to start some choppin'  

davidorchard (author)2006-07-13

this conduit you speak of, is it the same that electricians use? or is it actually tubing of a more structural use?

chadeau (author)KoolKat2010-01-06

...also approx welding settings and info on Silent Speedster hubmotor kit ----THANKS a MIL................

chadeau (author)KoolKat2010-01-06

Hey Kool Kat-canyou pass on my e-mail address to Brad G ? I need to ask him on some components in an electronic circuit found in Make...I'm at   . .circuit is Altoids mystery box-hidden noise prank

Coati (author)KoolKat2008-12-23

Electrical Metallic Tubing,I'm not a a grammar nazi just a disabled electrician.Sick bike by the way,I have always wanted to try one but was afraid my welding skills would fail me,no good with the thin stuff.My Pops just bought a new mig that will do stainless and aluminum and I imagine has better heat control.We are in the process of having a 30' x 50' shop built so hopefully I will soon have room to play.

Expertmurderboy007 (author)2009-08-22

how to get the grips off and on

chef (author)2008-03-03

what kind of conduit did you use for the forks???

chadeau (author)chef2009-08-09

...ya,thet's why I'm lookin here-tubing type and sources...he did say conduit-EMT seems too weak.......agggh-brain lock-up.....

dinzel85 (author)2009-04-05

This is the best bike ever!

itsaidhi (author)2009-03-21

how would you get a kickstand. sure don't just want to set it on the ground.

zak.gillies.oo (author)2008-08-24

i'm in the process of making 1 out of a three wheeled huffy green machine so it can drift better

jinnan_tonnix (author)2008-03-21

I like this. I've dug out a 25 year old ladies racing bike and started hacking... I've got a couple of twists to add; if they're successful I'll add them as an instructable. For the forks, I've found a local steel pipe warehouse - I had an 8-foot long 1.5 inch tube for £2. Bargain!

camb00 (author)jinnan_tonnix2008-04-30


jinnan_tonnix (author)camb002008-05-01

Yep - two UK pounds. That ware house is a treasure-trove full of off-cuts of all shapes and sizes. I started chopping a 25 year old Raleigh Wisp (see pic). I've only done the forks (see pic) but I'll finish it this summer and post an instructable.

tilbrook (author)2008-07-18

Hey, did you actually use an arc welder for this bike because I thought it would melt through the thin bike frame.

DuctTapeRules! (author)2008-06-28

'"Turn down that devil music you crazy kids!'" Best. Old joke. Ever. Pretty cool bike, too!

losdinspace (author)2008-02-10

Sorry the pic did not work but here it is.

losdinspace (author)2008-02-07

Here is mine, I am waiting for the snow to melt so I can ride it more.

ItsTheHobbs (author)2007-08-16

you've inspired me to try makin my own bike btw, your site is so awsom

rollerdame (author)2007-04-18

BEAUTY Koolcat! check out these cats...

KoolKat (author)rollerdame2007-05-22

AWESOME! We'll put a link on our Links page this month. You folks are way cool!

Larvice (author)2006-08-08

Great instructions and a great bike you made! Do you think it could be made with a gas welder?

KoolKat (author)Larvice2006-09-21

You could do it if you have one, but wouldn't recommend going out and buying one just for bike building like this. Too expensive and welds don't always hold up very well, in our experience.

ageyfman (author)2006-09-08

sweet bike - congrats - in another instructable, you should put together an explanation on how you painted it - it looks sweet!

yitong leo (author)2006-09-01

front-wheel drive very big:(

Generz! (author)2006-07-30

Hey man, nice chopper. If you are on myspace, check us out:
Bone Shaker Bikes

Generz! (author)Generz!2006-07-30

OH, btw, did you reinforce your front dropouts at all, or just weld them on as pictured? They look susceptible to breaking off... or do the super long forks take up the necessary shock from rolling uneven terrain?

KoolKat (author)Generz!2006-08-15

Dropouts were welded as is. Definitely don't wanna ride this baby over potholes, jumping curbs and speed bumps. The welds have held up so far. Not designed for long distance rides, but the "shock and awe" factor is worth building it. People tend to like this old school type of bike. Reminds them of their younger years, I guess. Stop by our forum when u have a chance.

KoolKat (author)Generz!2006-08-15

Sweeet bikes!

Alecw35 (author)2006-07-26

I got a lot of old bikes. But thought there was no use in those ladies bikes. Think I'll get my grinder ready. Theres a forum called They go on about Raleigh Mixtes. They are multitube frame ladys racer bikes. I got one that Im going to sort up.

trebuchet03 (author)2006-07-13

Beautiful... the gusset is a nice stylized touch. Curious... how long did this take you to complete? Oh how I wish I had a welder :P

KoolKat (author)trebuchet032006-07-13

Thanks very much! Took less than 3 days to build, 2 days for priming and painting, then at least a week for the paint to cure.

trebuchet03 (author)KoolKat2006-07-13

oh wow, that's you :P That site came up on one of the blogs I follow..... if only I had a welder :P

KoolKat (author)trebuchet032006-07-13

You know, you can buy a basic arc (stick) welder for well under $200. The one that we use was about $175 CAD. You don't need to spend a lot of cash to make the kinds of projects we build.

intoon (author)2006-07-13

nice instructable, one of the best yet!

KoolKat (author)intoon2006-07-13

Thanks so much for the nice comment. We have forums, a blog, videos, games and a builders gallery where you can see more bikes, robots, spy gadgets and other interesting stuff. Maybe we'll see you there some time! Your projects are great!

radiorental (author)2006-07-13

'effing awesome, love the reuse of the forks - nice one!

KoolKat (author)radiorental2006-07-13

Thanks! Cool tip on cutting onions without the tears. I never knew that!

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