u/OverAd8291

This is the third and last part of the conversion of this BMX bike into a cargo bike. I already covered the fabrication of the basic cargo rack and how I temporarily mounted it to the frame (mock up) so that I could fabricate the permanent mounts to the bike frame. Last section I covered how I mounted the front mounts and this will go into mounting the rear mounts.

MEASURE AND ROUGH CUT THE REAR STRUTS

I measured the distance from the cargo rack to the drop out below it and cut two pieces of 5/8" square tubing. Then holding it in position with my left hand I used a piece of soapstone to mark the angle cut it would require in order to mate flush with both the bike frame and the cargo rack.

Since I cut these by hand I need to have guidelines that I can follow for the cut. I will take the first line drawn with the soapstone and with my square draw the line all the way around the piece so that I could cut it corrrectly from any angle I were begin the cut. For small cuts like this I just put a cutting disc on my angle grinder and slice it following the guidelines I drew in the previous step. Also as I mentioned before I use a piece of wood to lay the metal on so I can cut on that and not on the bare steel table which will leave cut marks on it otherwise.

USE MAGNETIC HOLDERS TO PLACE THE STRUTS IN POSITION IN ORDER TO TACK AND WELD THEM

If after cutting them by hand the cut need fitting I will use an emery disc or file to remove any metal that is needed to get it right. After making sure that the struts will fit correctly I used a set of small magnetic holders to attach them to the frame exactly where they needed to go. Once they are in position I eyeball them from the side so that I can make sure that both sides match exactly to the eye.

This is an important detail as even though structurally they may work fine, the eye will catch subtle differences for example if one strut is angled slightly more than the other. The eye will see. I then tack them, remove the magnets and welded them out.

AFTER INSTALLING THE REAR STRUTS I STUDIED THE PROJECT TO SEE IF IT NEEDED ANY FURTHER WORK OR ADJUSTMENTS.

Once done the rack was installed and I had a chance to study it and see if it needed anything else before considering it done. I considered the fact that one of the intended purposes was to have her younger daughter be able to ride on the cargo rack and be able to strap her small bicycle on the rear of the cargo rack in the event she tired out on one of their outings and needed to be carried back home.

This meant that the rack had to be able to withstand maybe up to 100 pounds of weight in order to accomplish the intended use. While her little daughter and her small mike would not weigh that much, I had to anticipate that the bike may have to go over a curb whose impact could easily put that kind of momentary weight on it from the jolt alone once it was weighted down.

NEED FOR MORE BRACES AND TIE DOWN LOOPS

It seemed to me that the cargo rack needed more mounts to give it more strength. Also some type of tie down loops. I consulted with my client and we agreed that it was better to over kill on the structure rather than under. Also that the tie down loops were a good idea to facilitate tying the cargo to the rack. I found that I had room to place a pair of small struts on the front of the rack and an extra pair of strut on the rear of the rack. This would brace the cargo rack significantly and allow it to carry a lot of weight.

PREPARE THE FRONT BIKE FRAME TO RECEIVE A SET OF NEW STRUTS

In keeping with the design that incorporated pads welded onto the bike frame which would serve as mounting points for the rack's new front struts, I cut a pattern out of paper the exact size I wanted the pad to be. This pad would be mounted on the head tube where the forks and handle bars attached to the bike frame. Two new struts would come down from the head tube and meet the frame on both the left and right sides. To go over the pad concept again: I could have welded the struts directly to the head tube itself on the one side and to the cargo rack and on the other side directly to the cargo frame itself. However in the event of a strong jolt or even a crash, an accident could rip out the front struts and damage the head tube if it ripped a chunk of metal out of it.

CUT AND FORM THE FRONT PAD FOR THE NEW FRONT STRUTS

The design called for welding a pad directly to the head tube itself. Then two struts (more like gussets) would come down and angle outwards and meet the cargo frame. I transferred the paper pattern to a 1-1/2" pipe and cut the pad out. Since the head tube is round and about 1-1/2" diameter I chose the pipe as it is already round and would not take much effort to shape it to the same diameter as the head tube. Using the point of my anvil I use for just such situations, I opened up the pad I just had cut out so that its inside diameter matched the outside diameter of the head tube.

WELD THE PAD ONTO THE HEAD TUBE AND CUT THE NEW FRONT STRUTS, TACK AND WELD INTO PLACE

I clamped the pad onto the front of the head tube, tacked and welded it into place. It was large enough to allow mounting of the front struts. Following the same procedures as with the rear struts I measured the rough distance from the pad to the cargo rack and cut the two pieces for both left and right struts. Then holding them in position with my hand I eyeballed the angle drawing them onto the square tubes. I followed the same procedure as with the rear struts using the magnetic hold downs and tacked and welded them into place.

MEASURE AND CUT THE NEW REAR STRUTS

The rear struts were going to go from the drop out to the most rear part of the cargo rack at an angle. I used the same procedure as with the other struts and cut them to rough size and then fitted them by drawing a line where they met the drop out area of the bike frame. I tacked and welded them in place.

ADDING THE TIE DOWN RINGS

After welding the last struts into place, the last part left was welding the tie down rings into place. I went by my local hardware store and bought eight 3/8" washers. I spaced these out evenly on the front and rear parts of the cargo rack and welded them into place.

MODIFICATION TO THE FRAME WERE DONE DETAILS LEFT TO DO

At this point all that was left was to take care of details. For example this frame was based on front and rear hand brakes. The front hand brake would not function in the design chosen because the cargo rack got in the way of the brake lines. To solve this I went instead to a coaster brake, eliminating the need for hand brakes altogether.

I cleaned all the welded areas and it was done.

FINAL THOUGHTS

Once you have metal working tools and knowledge of how to use them it opens up a lot of possibilities on many levels. With just a welder, a grinder and some basic hand tools you can do a lot. For those out there that have been thinking of adding things or features to your bike it is not difficult to do.

This holds true for any type of venture where metal working can serve a purpose for you. You can make art, repair metal items, make tools, modify stuff, build pot hangers, etc. etc. etc.

If you've been thinking about it, don't hesitate, you won't be sorry. You can start off with a cheapie welder from Harbor Freight or buy a used one off of craigslist.

A gentleman brought me a cracked chain stay off of a 2002 Specialized Mountain Bike. It was broken on the sprocket side of the stay right where the hinge casting was welded onto the tubes. He brought me a broken one to use to scavenge material off of if I needed to and it had broken right at the same spot.

These repairs are pretty straight forward. They are also tedious. The repair calls for welding the crack shut. Then plating it on the cracked side with a piece of aluminum plate curved to fit the inside contour and then welding it in.

MAKING THE CURVED REINFORCEMENT PLATE

The hardest part was making up the curved plate that would fit inside the chain stay and get welded over the cracked area. To accomplish this I used a bending jig I made up years ago that has a variety of bending points to bend a variety of materials of differing heights and widths.

1. I bent a piece of wire to follow the contour of the curve of the chain stay to use as a template.

2. I bent a piece of aluminum plate in my jig to match the contour of the wire template.

3. I made a paper template of the size of the plate to be welded in.

4. Using this template I cut a piece that would fit inside the area to be reinforced.

5. I tacked it in place and welded it out.

Repair came out well.

IMPORTANT NOTE:

I always tell people who bring hardened frames to me about the need to have the part or frame hardened after welding on it. However if they are street riders or mild trail riders hardening is not as essential as if they were serious off roaders that continuously beat up their bikes. 6000 series aluminum will air harden and regain some of its hardness. Not factory hardness but enough to be able to use the bike without issue as long as you keep to the street or mild trail use AND if the welded area is reinforced.

Some choose to have it done, others don't but they have the option. Need to say this to let those who are quick to criticize such repairs because they are not hardened. It is up to the user to do so. I can't make someone harden their frames or part.

A lady brought me an antique cast iron sink with the date cast into it of October 31st, 1929, just a few days after the great depression set in. A chunk had been broken out of the drain and was missing.

THE PLAN OF ATTACK

The way I approached this repair was to locate a piece of standard schedule 40 steel pipe and splice it in and add the missing flange area where the drain would fit. To do this I made up some templates out of some file folder cardboard which was stiff enough to work with yet not too thick to be bulky. When I was satisfied with the fit of the template I copied the shape to the pipe, cut it out and welded it in its place.

THE WELDING PROCESS SELECTED TO NOT OVERHEAT THE MATERIAL

I usually braze cast iron with a torch but decided to use silicone bronze rod with my TIG torch. In order to keep the heat as low as possible I decided set my machine to AC as opposed to straight polarity that normally is used when welding ferrous metals. I did this because the AC cycle goes from straight polarity (heat input into the work piece) to reverse polarity (heat goes into the electrode and away from the base metal) at 60 cycles a second (old school non adjustable cleaning cycle tig welder). This made the welding process cooler than if it were just straight polarity. I ran a few practice beads on some scrap steel that had been ground shiny to get my heat settings and speed down.

USE OF SOAKING WET RAGS AND SHORT WELDING BEADS

In addition I chose to weld in short beads of no more than about five seconds at at time and let it cool before striking the arc again. On top of that I kept a soaking wet towel wrapped around the piece to absorb any excess heat. I was being very carful to not set up a situation where the cast iron would crack on me. You can see in one of the pictures I did small tacks all the way around the piece being spliced. The idea was to not let it get any hotter than my bare hand could stand when touching it.

FIRST SPLICE IN THE STEEL PIPE AND THEN BUILD THE MISSING TOP FLANGE AREA

After welding in the steel pipe I fabricated a cardboard template for the missing flange and then cut it out of some 1/4" plate and welded it in small beads at a time. Finally I ground it all smooth and ran an emery flapper disc to polish it.

The repair came out ok.

I was brought a 70's vintage Ford 351 four bolt main cast iron engine block to repair. It had a rear end corner broken off where it bolts to the transmission bell housing. The repair involved cleaning the area to be welded down to bare metal, beveling the joint, lining it up and clamping, then welding it out.

BRAZING MY PREFERRED METHOD FOR CAST IRON

In general I prefer to braze cast iron. It was how I learned to repair it back in the 70's when I worked in the steel mills back in Chicago. The things we brazed were large assemblies like machine bases or machine parts. We heated them up to around 800 or 800 degrees and then brazed them while hot. After brazing them we covered them with asbestos blankets and let them cool slowly.

BRONZE FLOWS REAL NICE WHEN YOU REACH TEMPERATURE

Once the right temperature is reached which is a dull red, brazing filler metal flows real nice and is a pleasure to weld with. You can tell you have it at the right temperature because it will start to flow out. When cold it tends to ball up and then flows out when hot.

The pictures show the progress of the repair.

It came out OK.

Here is another seat post repair I did five years ago. I looked up this gentleman today to see how his repair held up over the years. He sent me these six pictures showing before and after. He is still riding it five years later.

I wanted to make a point that welded aluminum bike frames can still be safe to use PROVIDED they have been properly braced and reinforced. The only condition is that to allow for a safety margin, do not use them for hard off road rides. That's not to say they won't hold up, but just to play it safe. I say this because some of my clients who I repaired chain stays, swing arm suspension bikes, head tubes, seat tubes, top tubes, etc. who were hard riders still used them like that against my warning not to. Again with no incident but in my opinion, that was pushing it too far.

Had a gentleman bring a van to me to build a fold up split bed in his van. He is modifying his van for overnight travel and be able to have comfortable sleeping quarters while on the road, camping, etc. By having the bed be able to fold up it leaves room to be able to transport bikes or a quad, etc. When he arrives at his destination, the bike or quad gets put outside and the bed folded down.

One of the problems that had to be dealt with is that the bed extended out beyond the sliding door about half way when folded up. This blocked the doorway from being able to use the van for work or for loading equipment into it. To overcome this I made the corner that stuck out into the doorway able to fold back so when that side was folded up, the went as far as the doorway but did not stick out into it.

HOW THE BED IS HELD UP

One side of the bed folds down and has four fold down legs that support it. In addition it has about six steel tabs welded on to the frame along its length so that they act like a shelf where the other half can rest against when it is put down. Thus the one side with the legs supports the opposite side .

When folded up the bed halves are held up by a tab with a hole drilled into it that is welded to one of the van's ribs up high. when the bed half is up it is pressed against the center rib and a pin goes through the tab's hole and keeps the bed up.

The project was more detailed than I first started because during the course of the fabrication certain things became apparent such as the need for two more legs to support the ends, or the need to put stops into the fold down legs so that can only go so far and will not swing up the opposite way inadvertently.

Another feature that wasn't apparent at first is that one side of the bed can be used when traveling alone and the other side pinned up making room for cargo, etc. In short it can be a single bed or a double bed.

FINAL THOUGHTS

Overall the bed project turned out well. As I told the owner, this was version 1.0. The next one will require less work thinking out its design as that bridge has already been crossed. It will be refined better as it goes along.

Hope you like it and that it gives you ideas for building your own.

Hello all,

I'm a retired welder that specialized in repair welding of all types from heavy to the delicate. I would like to get into adding disc brakes to bike frames. I had a gentleman bring me some disc brake mounts to weld on to a frame and he brought along with him a jig that bolted onto the drop outs and positioned the brake mounts in their exact location. Does anyone know where I can get some plans for building one? Attached are pictures I took of his set up.

Any help is appreciated.

Hello all,

I'm a retired welder that specialized in repair welding of all types from heavy to the delicate. I would like to get into adding disc brakes to bike frames. I had a gentleman bring me some disc brake mounts to weld on to a frame and he brought along with him a jig that bolted onto the drop outs and positioned the brake mounts in their exact location. Does anyone know where I can get some plans for building one? Attached are pictures I took of his set up.

Any help is appreciated.

A gentleman brought me a bicycle that had a broken seat tube right where it meets the top tube. Someone had welded it before but did not brace it in any way so it inevitably broke again.

Welded joints are inherently under constant stress due to what is called the "notch factor". When metal is welded it expands and then shrinks as it cools pulling against the surrounding structure. If the welded part is bearing a static load, this does not pose a problem as there are no additional stresses on the joint. However if the structure is subject to vibration, shock, sudden loads, etc. the metal at the weld will rapidly fatigue and break at or near the weld. This is why any repairs to such a structure MUST be reinforced with additional bracing (usually a plate). That's why this head tube broke again.

I ground the old weld off, re-welded the break then made saddle to go over the area and added a gusset where the top and seat tubes meet. Since its an aluminum frame, I informed the rider that it can no longer be trusted for off road use. It is now a street or mild trail bike only. The repair came out well.

A gentleman brought me a bicycle that had a broken head tube right where it meets the top tube. Someone had welded it before but did not brace it in any way so it inevitably broke again.

Welded joints are inherently under constant stress due to what is called the "notch factor". When metal is welded it expands and then shrinks as it cools pulling against the surrounding structure. If the welded part is bearing a static load, this does not pose a problem as there are no additional stresses on the joint. However if the structure is subject to vibration, shock, sudden loads, etc. the metal at the weld will rapidly fatigue and break at or near the weld. This is why any repairs to such a structure MUST be reinforced with additonal bracing (usually a plate). That's why this head tube broke again.

I ground the old weld off, re-welded the break then made saddle to go over the area and added a gusset where the top and head tubes meet. Since its an aluminum frame, I informed the rider that it can no longer be trusted for off road use. It is now a street or mild trail bike only. The repair came out well.

A gentleman brought me a bicycle that had a broken head tube right where it meats the top tube. Someone had welded it before but did not brace it in any way so it inevitably broke again.

Welded joints are inherently under constant stress due to what is called the "notch factor". When metal is welded it expands and then shrinks as it cools pulling against the surrounding structure. If the welded part is bearing a static load, this does not pose a problem as there are no additional stresses on the joint. However if the structure is subject to vibration, shock, sudden loads, etc. the metal at the weld will rapidly fatigue and break at or near the weld. This is why any repairs to such a structure MUST be reinforced with additonal bracing (usually a plate). That's why this head tube broke again.

I ground the old weld off, re-welded the break then made saddle to go over the area and added a gusset wher the top and head tubes meet. Since its an aluminum frame, I informed the rider that it can no longer be trusted for off road use. It is now a street or mild trail bike only. The repair came out well.

I'm a repair welder and have been doing frame repairs for many years now on most common bike frame metals. Its a small part of repairs I do. I use tig or torch brazing. This cargo bike came to me with a cracked chain stay near the drop out. The tube was cracked almost all the way. The procedure I use is to drill holes at the ends of the cracks to prevent them spreading. Then I weld the crack and grind it smooth. Then I make a saddle to fit over the welded area to reinforce the repair. If this is not done, the crack will reappear. In this case I had to shape the saddle so it would fit over the the rail and into the drop out plate. The repair came out well

NOTE: I get some comments that aluminum frames should not be welded as they are not safe, my answer is that the function of the plate is to add mass to the welded area and helps to strengthen it structurally. This compensates for loss of temper. I've been doing them for over 20 years without incident. For hard off road riders I warn TO ONLY use them as street bikes after the repair unless they plan on having me send it to be heat treated. Some have and some haven't.

I'm a repair welder and have been doing frame repairs for many years now on most common bike frame metals. Its a small part of repairs I do. I use tig or torch brazing. This cargo bike came to me with a cracked chain stay near the drop out. The tube was cracked almost all the way. The procedure I use is to drill holes at the ends of the cracks to prevent them spreading. Then I weld the crack and grind it smooth. Then I make a saddle to fit over the welded area to reinforce the repair. If this is not done, the crack will reappear. In this case I had to shape the saddle so it would fit over the the rail and into the drop out plate. The repair came out well

NOTE: I get some comments that aluminum frames should not be welded as they are not safe, my answer is that the function of the plate is to add mass to the welded area and helps to strengthen it structurally. This compensates for loss of temper. I've been doing them for over 20 years without incident. For hard off road riders I warn TO ONLY use them as street bikes after the repair unless they plan on having me send it to be heat treated. Some have and some haven't.

I'm a repair welder and have been doing frame repairs for many years now on most common bike frame metals. Its a small part of repairs I do. I use tig or torch brazing. This cargo bike came to me with a cracked chain stay near the drop out. The tube was cracked almost all the way. The procedure I use is to drill holes at the ends of the cracks to prevent them spreading. Then I weld the crack and grind it smooth. Then I make a saddle to fit over the welded area to reinforce the repair. If this is not done, the crack will reappear. In this case I had to shape the saddle so it would fit over the the rail and into the drop out plate. The repair came out well

NOTE: I get some comments that aluminum frames should not be welded as they are not safe, my answer is that the function of the plate is to add mass to the welded area and helps to strengthen it structurally. This compensates for loss of temper. I've been doing them for over 20 years without incident. For hard off road riders I warn TO ONLY use them as street bikes after the repair unless they plan on having me send it to be heat treated. Some have and some haven't.

i used to live in the White Mountains of Arizona and it gets cold in the winter. I started building wood burners of different types. Before that I lived in Chicago and those winters get fierce and is where I first started making them back in the late 70's.

I use water heaters because under the sheet metal and insulation is a strudy metal tank that is easily welded and durable. Electric heaters are best because they don't have the center vent pipe that requires the extra work of removing the pipe and then sealing the holes but they can work too. The pictures show the progress from an old water heater to a finished double barrel wood burner.

I had one up in our place in the White mountains and had a 30' x 100' steel quantum style steel building shop. When it was way below freezing I could work in that shop in a t-shirt it was that good.

Hope it gives you some ideas

I used to live in the White Mountains of Arizona and it gets cold in the winter. I started building wood burners of different types. Before that I lived in Chicago and those winters get fierce and is where I first started making them back in the late 70's.

I use water heaters because under the sheet metal and insulation is a strudy metal tank that is easily welded and durable. Electric heaters are best because they don't have the center vent pipe that requires the extra work of removing the pipe and then sealing the holes but they can work too. The pictures show the progress from an old water heater to a finished double barrel wood burner.

I had one up in our place in the White mountains and had a 30' x 100' steel quantum style steel building shop. When it was way below freezing I could work in that shop in a t-shirt it was that good.

Hope it gives you some ideas

Every now and then someone brings me an AC line to repair or modify. Sometimes someone is modifying a car, an engine swap or adapting AC to an older car. Sometimes the line is damaged for one reason or another. I got into this by chance when a friend who knows I weld aluminum asked if I could repair an AC line. I thought they were real thin and could prove tedious to weld but it turns out they are made from some stout tubing that takes to welding readily. It was not difficult at all.

Like everything, unless you try something you don't know what it takes. I have a Facebook page "Retired Welder Keeping Busy" where I post stuff I've done and try and explain how I do them or why a certain way to pass on things I've learned to others. Its a way of paying it forward for all those who helped me along my path as a welder.

Every now and then someone brings me an AC line to repair or modify. Sometimes someone is modifying a car, an engine swap or adapting AC to an older car. Sometimes the line is damaged for one reason or another. I got into this by chance when a friend who knows I weld aluminum asked if I could repair an AC line. I thought they were real thin and could prove tedious to weld but it turns out they are made from some stout tubing that takes to welding readily. It was not difficult at all.

Like everything, unless you try something you don't know what it takes. I have a Facebook page "Retired Welder Keeping Busy" where I post stuff I've done and try and explain how I do them or why a certain way to pass on things I've learned to others. Its a way of paying it forward for all those who helped me along may path as a welder.

A steel frame bike was brought to me with a pair of chain stay cracks near the bottom bracket. The cracks went almost half way around the stay rails. The standard procedure for cracks is to drill a hole at the ends to keep the crack from spreading. If this were thicker material a groove would be cut into the metal for penetration but because bike frames are under an 1/8" this is not necessary as the weld penetrates through. Once welded, the bead is smoothed out and finally I made a pair of small steel saddles out of a scrap frame of similar size and welded them over the area to reinforce the repair.

This is necessary in all cases because as a general rule welds are always under stress by their nature as the heated metal first expands and then as it cools, contracts puling against the surrounding structure ready to crack again once stresses and loads subject them in use. Bikes, especially off road bikes are extremely stressful on their frames. Plating like this not only adds more material to spread out the load but also adds mass which provides a stronger repair as it shares the stresses along with the base metal.

The repair came out well.

A steel frame bike was brought to me with a pair of chain stay cracks near the bottom bracket. The cracks went almost half way around the stay rails. The standard procedure for cracks is to drill a hole at the ends to keep the crack from spreading. If this were thicker material a groove would be cut into the metal for penetration but because bike frames are under an 1/8" this is not necessary as the weld penetrates through. Once welded, the bead is smoothed out and finally I made a pair of small steel saddles out of a scrap frame of similar size and welded them over the area to reinforce the repair.

This is necessary in all cases because as a general rule welds are always under stress by their nature as the heated metal first expands and then as it cools, contracts puling against the surrounding structure ready to crack again once stresses and loads subject them in use. Bikes, especially off road bikes are extremely stressful on thier frames. Plating like this not only adds more material to spread out the load but also adds mass which provides a stronger repair as it shares the stresses along with the base metal.

The repair came out well.