Jordanjw

this is a new post as I already posted on vintage bikes as my idea is to weld a cargo bike together using an old steel frame as this would be more suitable for the use I'm intending to use it, my intended payload would be around 300kg all in, im going for a 3 wheel design this would be 2 wheels at the front for steering & one at back fitted with an electric pas system,
this needs to be made from steel as aluminium will be to weak and wouldn't be able to hold up even if i was to use 15mm and even so this would be decremental to the weight anyway i also do not like mig welding so i will not be partaking in that process as i can only weld aluminum using 4043 electrodes,

so i have drawn up a design but im finding it hard to source a bike that would be suitable for the build my main concern is the crank and heattube as i want to be able to work from a fixed position rather than working from scratch as t
his will be easier, has anyone had experience welding onto old steel frames or similar, other are saying the tube is thin im able to weld down to 2mm with what i have but obviously if the tubing is say 1.5-2mm anyway i don't believe this would be sufficient for my needs.



original design, i dont think front fork supprts would have been suitable after consideration to payload of 400kg


this also isnt the final design i originally had two individual risers for the front forks but now i want to go 90 degree from the bed and then 90 over the wheels as another light storage rack, also note im a welder fabricator, im not to fussed about the final weight all in all ive calculated it at around 35kg all in with the pas system, using 50x50x5mm box as i have already worked out deflection and this would be best suited for the use also unable to post picture as i need 10 posts so will post as soon as im able to



this was the second design but now ive opted for a rack above the front wheels and recumbent type front wheels and also the seat will be lower down in a recumbent style

havent yet drawn up final design will be in the next coming days - build will start tuesday as monday is a bank holiday and uploading pictures wednesday of the bed build as this will be the first thing to be built the bed itself is 1m long x 1.4m overall including the front support for wheel & rack - overall bike length around 2.8 m - width of the bed 580mm - height of the rack is 250mm high from the top of the bed by 400mm long also 580mm wide - clearance from floor in the 150-176mm range but this may change as once i build the bed i may lower the rack slightly

possibly the final design




the box is cut like this so that i gain an extra 25mm for the headset mounting which leaves me with a level bed above




final seat design - position not fixed as will need to suit pedals so will move, also the frame will need to be changed to suit the seat placement - may need a brace from top of headseat downwards also headset will be angled toward me



needs some adjustment on the drop outs on rear wheel, this can possibly be compensated on rear drop out that wheel attaches to as im thinking i can cut from 6 or 8mm steel

may need a slight bend at top where connects to frame

also some braces will be added on the main frame to the other piece of box that runs parallel

Andrew R Stewart 

I'm almost surprised that the OP hasn't just gone out and gotten (bought, found as throw aways) old mass merchant steel AtB bikes and then tried what they are thinking of. As a way to get a prototype going this is pretty cheap. very soon the OP will begin to better understand if their dreams are workable.

Cheap bike steel main frame tubes are often between 1mm to 1.5mm. The better quality bike shop grade bikes will see portions of steel main frame tubes as thin as .5mm in their central portions. Andy

Jordanjw

well considering the tubing is 1.5mm im glad i haven't yet, as this would need to be 3mm minimum and if it was 3mm id opt for seamless - im thinking of just buying an old bike and then using the bottom brack and headset and weld my own tube on, also i haven't done anything yet as i was waiting for steel delivery, i got it this morning so from tomorrow i will be starting the bed build and then i can worry about the bike once i have the bed together with also im in the uk so im finding it hard to find a decent range of steel bikes as most are just thrown away after use and not sold on, as long as say the bottom bracket is atleast 5mm thick this should be enough for my needs and also on the bike, any old used frames are going for £100+ which isnt really ideal if im going to cut it up, ideally if someone knows where i can get a raw steel bottom bracket that would help but this seems to be kept from public like many other components that are welded in the industry

dsaul

Since you are in London, I would suggest Ceeway for a source of raw steel bottom brackets. https://www.ceeway.com/NEWPARTSPAGES...B%20shells.htm You likely won't find one that is 5mm thick and I don't see any reason why that thickness would be necessary. If you want a steel bicycle frame made from tubing thicker than 1.5mm, you will have to make it yourself from straight gauge tubing. I don't know of any commercially available frame building tubes that are thicker than 1.2mm.

Jordanjw

thank you kind sir.
Also my maxium payload will be upto 400kg this isnt including myself just extras loaded on, from my standpoint i understand 1.5mm may be enough but from my fabricating experience i dont believe it will be enough for my intended use.
basically i want to use it as a work vehicle for welding/fabricating which will sometimes include a generator which comes in at 170kg which is my concern as even so aluminium can be heat treated but say i was to cut a piece of metal on the bed using a plasma cutter and somehow the heat transferred onto the bed frame then obviously we know whats going to happen.
and also im a stick welder this is another reason why i choose steel, i can tig and mig but at the moment the premises i lease requires permission to store gas bottles even though it is inhert but this permission comes at a cost of 395+ vat which is ridiculous imo. So therefore im only able to weld with 4043 rods which also inhibits me to weld ally as 4043 rods wont be enough for my use the tensile for 4043 rods are 270mpa & shear is 170mpa which ultimatley makes this weaker than the 6061 base material as this is considerably less than base material @ tensile 290 and shear 241 which will render the weld useless as it isnt as strong as the base material which will result in weld cracks and failures

guy153

Stick welding is going to be difficult even on a low-end frame (which is about 1.5mm as people have said). You would get away with MIG. For cromoly etc (0.6 to 1.0mm) you need TIG.

What if you made a 5-wheel cargo bike as follows: make a cart with 4 wheels. Get a bike, throw away the fork, and attach the cart to the bike via some kind of steerer tube which is welded to the cart (and has the usual bearings at the top and bottom of the headtube). The handlebar is fixed to the cart. So basically you have a stable cart with a bicycle attached to it which pushes it around. There are designs like this (I think they might be called "tadpole cargo bikes" possibly) although usually they have only two wheels on the cart, which requires more modification of the frame, but probably gives more agile steering. The only question mark over the 5-wheel design is whether it would be manoeuvrable enough.

Jordanjw

im able to weld 1.5mm steel with mma dont be fooled by unskilled welders and their techniques i stock 1.6mm rods specifically for sheet steel incase anyone needs a quick repair on something thin, obviously your not able to run it like mig or tig you need to draw heat from the welding area by using aluminium or copper as a heat sync or you do half the weld move on to the next and so on and then come back and finish, also this thread is a follow up of my op on vintage frame section as that was my original idea, someone on there mentioned a tadpole recumbent and im going for that type of design not fully the same but based off of that

ive found suitable tubing for the bike which is 3mm m/s which isnt what i wanted but im unable to find the correct diameter in s235 or equivalent steel, im not fussed about the overall weight of the bike as ill have the pas system installed also that idea is a great idea about the cart but as its a bicycle its pretty much able to go anywhere where a car or van cant, i also just plan on leaving the bike loaded at jobs and running leads from the bike, obviously i will make brackets for bolting and locking of whatever im carrying

as for the bottom bracket does anyone have any experience installing these as the one i intend to use is 33.95 mm ID ive found 34.1mm od my idea is to get a 34mm drill bit to get it down and then im hoping i can squeeze the bracket in - if this doesnt work i could come up with an idea to ream the inside of the pipe it cant be that hard it only needs 10mm ~ or so

guy153

Yes stick is possible on 1.5mm with enough skill-- although I know I couldn't do it!

3mm is really overkill (but no harm in that). 1.6mm would probably be fine, or around 2mm if you can find it.

Ceeway do 40mm BB shells so those have a wall which is nearly 3mm thick (the usual OD is 38.1mm). Those 40mm shells are already threaded for a BSA bottom bracket (although other kinds are available) and the advantage of the extra thickness is you can often get away without chasing the threads after welding. They're cromoly so extremely strong. I would get one of those. They cost less than £10.

If you want to use the bit of tube you have I would try to get it to the right ID for some kind of press-fit BB with a boring bar on a lathe. In theory you could cut the threads you need for a threaded BB with the lathe if you know how to do that. Otherwise if you have an adjustable reamer and a lot of patience you should be able to get there in the end (for press-fit).

Jordanjw

Not to discredit anyones skill but mma is usually done on thicker material obviously, and ive emailed them about material specs as i know chromoly will be more than enough for the frame but its just finding a suitable rod to weld chromoly to s235, im under the impression a 309l or 7018 will be fine, i wonder if youve had any experience with this? Finding newer exotic type electrodes for mma can be a pain as its mostly aimed at mig or tig these days

and to be honest i welded some chromimum the other week which i assume is similar to chromoly just slightly different composition, and it took 2 flap disc to get a weld to be flush with the base material and im only talking about a 20mm weld long which was only around 3-5mm off the base

Yeah i was also thinking i could maybe get a carbide bit for the drill and attach it to a vice and then work the pipe around may be time consuming, either that or i could get it lathed to size but obviously its unwanted cost if i can get the chromoly type and find electrodes

You also probably missed in my other post i can tig and mig but the premises i lease requires permission to store any gas this include inhert, but this comes at a cost of 395+ vat and a alteration form and other paperwork, as i only took the lease out in feb this year ive already spent in excess of 10k+ already moving in and need to recoup before i actually go mad spending on little things like that especially when ive got the mma machine there

dsaul

Your design needs a brace tube between the bottom bracket and the bed, preferably with some triangulation to prevent the rear from wagging like a dogs tail when you ride it.

I TIG weld all of my frames with ER312 stainless filler, because it works well at joining dissimilar steels like stainless to chromoly or mild steel. A quick google search showed that there are stick welding rods available in SS 312, which should be good for joining chromoly to mild steel.

Jordanjw

thank you, also that is more a preliminary drawing for the bed with just a frame added on i havent added that brace on yet as im focused more on the bed for now as thats going to be the most time consuming thing and also alterations on bed as its being drawn which makes it alot easier than actually building it infront of you then doing it after its been tacked up, and i get a basic cut list which also helps on the day, i was also looking at ss for the frame but it can be brittle under stress at times and also costing would be unsuitable as im probably looking at around £1000 possibly a little bit more for the build

ill also compare composition of those compared to 309l as this is kind of a grey area as ss shouldn't really be welded to m/s as galvanic corrosion can be an issue obviously it can be done but without care it can happen

guy153

For welding cromoly, Reynolds (non-stainless) tubing, and mild steel you can just use the regular mild steel TIG rods (called A15 in the UK, and ER70S-6 or ER70S-some other number in US). Some people use stainless rods for everything because if you are attaching stainless to anything you need a stainless rod (and they're also fine on cromoly-- some people think better). I use A15.

Haven't used S235 to my knowledge but I think it's a fairly mild steel anyway. So if you're doing stick the cheap rods they sell in UK for sheet metal like 6013 will probably be fine. I would do a few test joints and then break them. Will tell you nothing about fatigue but still worth knowing that the basic strength is there!

But you can consider cromoly equivalent to mild steel when it comes to welding rod choice.

guy153

So how does it steer? Are the two forks at the front fixed, and the whole front end rotates around the bicycle's steerer tube? Or do you make that joint rigid, link the forks together, and have them steer? (And you might need to work out how to do the proper Ackermann geometry if you do it that way).

Jordanjw

So im going to use the normal cargo extension that clamps onto heaset tube at low level and extends to front wheels but i will use either m12 or m10 as from experience the m8 isnt strong enough and sometimes throws the front wheel off to the opposite side of the connecting rod which is annoying.
and it will possibly have some sort of recumbant steerer for the other fork, and no the bed will be ridgid but as i said im looking at recumbent style mounting and this could be an option and also a possibilty of adding suspension either forks or recumbent style for the wheel fixing

If the above website also stock headset tubes in 3 or 5mm ill opt for recumbent style but will possibly add supports either side but not in a fork manner, obviously once the initial bed is built i can move forward from there as id need to see certain things infront of me to solve the problem
also without certain sizes of headset etc as they come in different sizes im unable to really draw it up accurately to get a better look at how it performs in terms of steering and movement

I will get the bed built up for now and then once i get a response from the above website i will then ask about the headtube or headset

Also the fixing point for the headset will be either on a fixed piece of box section with tube on the inside for the headet thats welded to the underside of the frame to allow for headset to be mounted without tampering with above rack ie keeping the bed level
or it will be recumbent as in drop outs from the frame for wheel mounting etc

guy153

I doubt Ceeway will have any head tubes in anything other than the much thinner walls you would use for building a medium or high-end road bike (they stock Columbus tubing). But if you can find anything with a 34mm ID that's what you will need for a regular 1 1/8" headset. Bicycles tend to use somewhat deliberately non-standard sizes.

Jordanjw

Thanks for the info, i can source 34mm mild steel or 34.1 but as said i can drill out with a 34mm drill bit, im working on the drawings and will post when updated and try to add all additionals to show setup

unterhausen

I feel like you should consider a design with some triangulation so everything doesn't have to be so heavy. I gather part of that is due to available welding tech, but you still have to ride the thing.

Jordanjw

yeah i know, i used to ride a cargo daily for a year and do upto 120 miles in a day, this was for work so im sure ill be fine, thank you for the concern but imo i dont think i can sacrifice to much of the frame as i need a solid base to load onto.


also does anyone know the answer to this; i have a headtube at 41.9mm and the headset is 42mm would this be okay or would the .5 play equate to play in steering at the minute im finding stock from supplier obviously this is hard to get all items from one as i need various sizes im just exploring options at this point in regards the headtube

duanedr 

Yeah, that won't work. You'll need smaller ID for press fit headset. But before you go there, I would explore making your own. Maybe you have and maybe you've done the math to prove this all out but, 400k is way over the typical operating range for current bicycle technology which is generally constrained to minimize weight.

My approach would be to mostly abandon current bicycle tech in favor of purpose-built headset, steerers, bearings and such - like you have with the rest of the frame tubing spec. I would at least call one of the high-end headset makers to make sure they are rated for your purpose. I would explore machining a race for adjustable tapered bearings into a thick tube like on a motorcycle. I just get nervous looking at that front end imaging a couple of medium sized motorcycles sitting on the platform as you pedal along. I have doubts typical fork steerer/crown/blades will support 400kg on bumpy roads with braking and turning stresses. Those stresses are lateral with this steering arrangement. Maybe you haven't gotten to that point yet... It seems you're adept at CAD so I would definitely look at the FEA analysis screens. Maybe you already have and I'm just overly cautious.

Cool project, I always think I want a cargo bike but then realize I don't really haul that much stuff around.

Jordanjw

yeah its a shame but i can believe the 0.5 being critical as its a steering column essentially, im opting for 3mm mild steel tubing at 1 1/14 diamater, i also saw a headset at 44mm im wondering if i could just get a 50mm piece of pipe o.d and then grab a 44mm drill bit and go down the the depth, i will get there regardless if they dont stock such items, also in regards to the fork setup im tempted to buy forks as its hard to find the internal tadpole recumbent style suspension
even so i think i can just make my own forks in regards to your lateral thoughts im thinking more a u shape and then i can drill a hole and weld the vertical piece that will attach to the headset which should limit stress on the forks as less weld points etc, obviously i dont know ive done the deflection calculations etc but obviously in practice you never know what will happen especially with load distribution, i said 400kg on the high end which will probably be once in a blue moon but i fully understand you concerns i think as a general rule overkill is what it needs, ive basically done that with the bed as its 50x50x5 box section

also are all headsets universal ie a 44mm headset will suit a 27.6mm fork? or is this to do with spacers inside the headset ?

duanedr 

For standard bikes, the HS is a standard press fit part. My uber-point is the extreme overbuilding of the platform will require overbuilding all the way out to the edges.

For bicycles, there is a matrix of standards. you can get a headset that takes a 44mm HT and allows 28.6 steerer. Here's specs from Chris King for headsets that should help - includes tolerances.
traditional-headset-spec-chart-2016.pdf (shopify.com)
inset-headset-spec-chart-2016.pdf (shopify.com)

Unless you use something stronger than a standard 1-1/8" steerer (ie thicker walls) and are trying to use bicycle standards as much as possible, I would go to a tapered steerer. Further, I would make it myself with thicker walls than we typically use for bikes. It seems you have access to required machines so I would use them. Don't compromise the design to use off the shelf parts that will not hold up. Even if you're carrying 100kg regularly, that (along with the weight of the bike and rider) exceed typical bicycle working range. I'm sure there are downhill bike parts that would help but, I think you're going to spend as much time trying to meet existing standards as you will just making your own.

Please keep us posted as you continue.

unterhausen

Headsets meet one of many standards. Cane creek has a chart. I think you can get to it from this page, which might have some info that you need.
https://canecreek.com/everything-you...bout-headsets/

Might be worth considering using a vertical head tube and getting trail by having negative rake. This is relatively common on recumbents

Jordanjw

cheers, i saw a cane creek headset i can use, any idea if the internal of the head tube is angled or is it just the insert depth into the tube itself in regards to the negative/ positive rake,
i highly appreciate everyone's replies it has helped alot

also the recumbant style seat hasnt been projected onto bike yet i will possibly update today/tomorrow

duanedr 

I don't understand the last question. I think what Unterhausen is suggesting is a vertical headtube and then using a fork that places the axles behind the headtube like a caster on a shopping cart. headtube and headset would be direct straight press fit.

Jordanjw

as in is the fork post all a universal size, because ive found a 28.6mm fork tube are all forks 28.6mm and if not what im referring to is the spacers inside the headset does that alternate for different fork sizes?

and ive found a press fit bb as it will be easier than trying to thread my own ill be posting updated pics and a list of components im going to be using on the bike

also wont be using chro mo due to how brittle it is i dont want cracks on my frame