Introduction: Swing Wobble Mountain Bicycle BSA Shot-Gun Break a Leg Horror Story Horcrux Bike.
saw a picture so the next day i made the frame. i took my camera with me so i could share the experience with you, subsequent research occurred while writing this up.
its a good project because you get a lot of bang for your time,effort and money. the components do not have to be great quality as its never going to be a high performance machine with exacting tolerances. its more about the aesthetic ,and with resourcefulness and imagination a maker will tell their story imparting a lexicon of their soul within the machine.
this is a vid of dad having a go on it. i promise it is ridable i will add another video.
heres a video derailer eye view vid if it riding
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Step 1: Parts & Materials
Frame and forks x2 sets, helps if fork steerer fits nice in seat tube. mine is 1 inch , older size commonly used on old bmx's kiddie bikes and really cruddy catalog/superstore bikes.
- frame 1 shockwave xt675 26er frame, with heavily modified suspension forks(had to replace forks due to dodgy geometry) £0 given by neighbour destined for tip
- replacement standard forks £15
- frame 2 bsa westcoast 26er frame and rigid forks.£7.50 ebay local house clearance firm
- cranks seatpost handlebars+stem breaks+levers gears +levers cables hubs+spokes freewheel/cassette.......bell+reflectors, all salvaged from other bike restoration attempts.£0
- saddle,im fussy so bought a comfy one for my ageing backside £10
- chain, a worn chain not only increases wear to cogs (they stretch) they've made many bike owners abandon usable machines, a basic chain from ebay £4
- pedals and chrome wheel rims+tyres tubes from an early 90s ladies mountain bike.£0 gift from cousin in law
- copper ease,£6(just like grease but has better high temperature tolerances)halfords or car parts shop.
- wd40 spray oil.
- degreaseing agent ,thinners ,methylated sprit ,rubbing alcohol, petrol.vodka.
- rags paper towel sleeve hampster
- abrasive paper ,
- paint car shop spray cans are good, using a good clearcoat makes a big difference. poundland (dollar store) spray paint is ok the colour choice and smell are not good.
- car body filler (bondo)
Step 2: Tools and Facilities
divided to clarify. *(yours may differ.)
- a flat surface,fire resistant...compressed air...blowtorch/heat gun...paint spray gun...extractor fan...warmish dry environment
to make the frame
- Hacksaw...bench vice...
wire brush...file....angle grinder...hammer(ball type and rubber type)
- Wielder,for this type of thin metal wielding i would recommend oxyacetylene,gas mig or brazing, iv only got gassless mig so its not pretty,(bondo it after)
to make a bike,
- spanners large small adjustable, pliers...pipe grips (headset)...allen keys....screwdrivers...crank extractor,..chain splitter/joiner,..spoke key,...cassette/freewheel tool...wheel jig,...wire cutters, file/bench grinder
Step 3: Cut Frame 1
this frame has the duff bottom bracket, so im only using the top tube and steerer, id recommend leaving a bit more of the down tube(diagonal one) on the piece your using to give more scope for geometric adjustments.
a note on geometry, seems like anything goes, so go for it , iv added some images of other swing bikes(source google) to inspire your creativity. iv picked a selection that show the variation in pivot angles, the added spring to the rear pivot is interesting.
Step 4: Cutting Frame 2
im using most of this frame, the seat tube is a good fit for 1 inch steerer tube, the bottom bracket is ok, and i like the bsa decals on it. this frame is smaller than the other so i try to minimize wastage by cutting close to the seat tube ,and by trying to keep the cut straight.
Step 5: Trim Pipe Ends
here a flat surface helps, you want to keep the head tubes paralleled or upright as your riding, or maybe you dont and feel the earge to have them perpendicular.
the idea being to get all the pipe ends to meet with a little overlap (or as much as possible) to make wielding strong connections possible.
Step 6: Teardrop Shaped Pipe Issue
- i found that a teardrop shaped tube though bigger in diameter than the connecting tube did not let it inside,
- it needed to be rounder, so i gently squashed it in a vice.
- sort of round with a bit of a flat spot is easy to make mostly round with a ball hammer than trying to make a pointy tube round with the same hammer.
Step 7: Start Wielding
- i didnt want rough surfaces made by angle grinding off paint, and i was certainly ot going to spend time sanding or using chemicals.
- i put some generous tack wields in, flames and smoke....
- the heat softens the paint in the area ,a quick wire brush clears it off
- then its ready for the final pass of wield.
Step 8: Might As Well Cut This Bit Off Now
later i added wields on the seams inside to strengthen it. i could have tried to cut the remaining tube off , instead i covered the inside hole with a little tape and filled the pipe end with body filler.
Step 9: Middle Pivot
- select a fork with a steerer longer than would be normally be used in the frame providing the middle pivot. as the protruding thread will be used to attach to the rear triangle section
- you will probably have to give the headset top nut a file or trim on the top edge so it passed over the thread.
- cut the fork arms off.
- grind the factory welds off so its round again,
- check it fits in the seat tube of the rear triangle section.
Step 10: Cut Rear Triangle.
choose between serviceability or clean frame lines, i chose the latter. lay the parts on the floor to get an idea where everything is going to go.
- dont cut out too much, because you can easily cut more.
- the frame will bend to allow more space during installation
- too low and your pedals will hit frame
- too high and you will not have anywhere to sit.
Step 11: Middle Pivot Prep and Final Service.
- technically your supposed to clean off paint before all welding to reduce fumes and not contaminate the wield., this is one of those times i started.as metal overlap is limited.i was still a bit slack tho.
- if your using this headset upside down remember to swap the cones if necessary (details in later step)
- put lots of copper ease or high heat grease inside and around the bearing cones and cups as possible.
- tighten it up
- clean off excess gunk especially on the bits going to be welded.
Step 12: Assembely
- much easier if the triangle is held in a vice as it makes twisting the frame easy,
- put the longest end in first., a rubber hammer will help and not dent the metal.
Care about it as little as the person originally assembling the bike in the factory, then it will fit in no time.
Step 13: As Soon As I Cut My Triangle It Sprung Open
to keep the shape while i weld , a stringy type thing pulls it into shape.
Step 14: Not Planning to Service This Part.
it will look better after paint.
Step 15: Geometrics and Paint.
by attaching basic components to the frame,wheels forks handlebar and (loosly) cranks,this is my preview of the kind of shape its going to be,i decide im not keen on the extended suspension forks, ebay for new forks, standard rigid with a really long steerer.luckily they come in black as standard.
prepare for paint. turn a heater on,..re-strip the frame of parts
- MY TOP TIP for this stage, a junk saddle stem and handle bar set fitted to the frame make it much easier to maneuver in tight spaces while cleaning and painting as it gives you an area that is not out of bounds for your dirty hands or when wet paint is about..
- remove unwanted decals(i want to keep the bsa set but not the shockwave) heat softens stickers,(blowtorch)
- wd40 remove any sticky residue old grease and dirt...degreaser or thinners removes oil and fingerprints.
- use bondo or car body filler to smooth up any particularly ugly wields....file and sand the filler to shape
- remove any dust from the frame and surrounding workbench paint spray area
- wipe the frame with a CLEAN cloth then avoid touching it henceforth.
painting (from experience bendy frames behave as though they are possessed while paint is wet or soft)
- as the bsa frame is black(the one im keeping the decals of) my colour choice is therefore made
- mask decals with electrical tape or similar...spray very lightly around masked areas if at all.(dont want a paint ridge here.)
a little squirt should be sufficient over any chips or scratches..spray the wrong colour bits blending into the existing black paint.
Step 16: Fancy Clearcoat
im using a two part clearcoat, 2 parts of the big can to 1 part of the little can, accuracy here does not seem critical, the little can makes it dry quicker,as does heat. this stuff sprays on thick and smooth,and does not run much compared with most other paint..
before using a spray gun at any time be sure you have the means to clean it well.
Step 17: Mid Clearcoat
i neglected to turn the extractor on to keep the shop warm and help the coat dry. the fog haze doesn't look so much in the photos.
Step 18: Behold the Shine
Step 19: Swap the Front Cups
as the front steering tube is effectively upside down, the cups may not allow steering to be possible because they have different hights,
Step 20: Using Junk Parts.
The crankset im using was heavy, had a lot of wear to the middle ring , and the cogs were loose on the arm.
- reduce weight by drilling out the rivits holding the smallest chainring and removing it
- the middle ring connects between the large chainring and crank arm so im stuck with it. Im only using the large ring to drive the bike.
- to assist the loose compression (i think) connection between the armand ring i ran a wield around both sides.
the shifter i was originally using was missing the plastic component that secures the cable,i made use of a v brake noodle to workaround, i later found a better lever.
Step 21: More or Less Thats the Components.
fitted in a mostly standard manner.
cables need to be longer and looser around the bendy bits.
cranks pedals and saddle have to be extra tight ,they are your bodys connection to the back half ,and will be subject to additional twisting forces.
i later added a caliper front brake, because that was the first thing people commented on, i mean come on really why would you want a front brake that collapses the frame, the caliper preforms suitably terribly so everybody should be happy.
Step 22: Gallery . Other Changes
- swapped the handlebar and stem for a lower black straight set.
- added reflectors and bell
- front brake
future mods possibly
- front derailer
- two tone paint or colour change glaze
thanks for reading ,i hope you enjoyed, please comment and check out my other instructables. G
Step 23: Exploring Geometry
i made 10 cardboard cutouts of bikes with a basic set of permutations for the front and rear pivots.here are my observations
- A steep rear pivot makes the bike lean to one side,if its positive rake the bike will lean into the skew, if negative rake it will lean out of the skew, the rider will compensate be leaning back , effectivly raising the bottom bracket .*6
- if the front pivot has more rake (sticks out more front at bottom) i relation to the rear pivot,when the bike is skewed the front wheel will be stick out more to the side the bike is skewed to.pointing its handlebars towards center or the rider.*9 *3 *5
- less rake on the front in relation to the rear makes the bikes skew more noticeable in the handlebars,and the front will will lean down to center.*7 *8 *10