I thought the great thing with joining copper pipes is that the joints have solder built into a ring inside - as shown here. From the top picture of the TTR, it looks like those sort of joints were used.

With pre-soldered joints, all you do is link up and blowtorch it - the inner solder ring melts, cools and seals. Even i could do that although perhaps it's not as strong as hand soldered?

If an epoxy resin filling is the key to strength then I wonder if that makes aluminum tube an option and possibly cheaper too? Easy joints here or here (UK)
And copper or ally, could the epoxy double up as joint glue too?

I have done a fair bit of stainless steel handrail / ballustrading that is joined with epoxy and that works very well but uses precisely engineered fittings that have a couple of o-rings to control the glue.

In my opinion, copper tube just isn't up to the job for a rack though; it's too soft and I'm pretty sure that size for size, it's heavier than steel. Easy to work though and might be a way of putting together a prototype.

I use good quality seamless steel tube, with end plates or buckets at fixing points. I don't like off the shelf racks with the tube crushed and drilled for fixings. Easy, cheap but a bit crappy IMHO.

Here's one to throw into the mix........strength for weight, you'd be hard pushed to better wood. Some nice spruce would make a very strong rack :-)

In that case what is your opinion on these hex key joints, BYT?
Am I right in thinking they would need a fairly thick-wall tube not to deform under the screw and so you end up needing unnecessarily heavy tubing?

I think the key with copper is it's easy to join + the resin filling gives the strength as McC has shown. But it might get heavy on a full rack.

I agree. The last OTS bike rack I had had fittings like that. I was rather surprised. Acceptable if DIY but not when paying 220 quid +.

Talking of other materials reminds me of this one - a strap-on plastic platform rack, heated into shape.

Attached Thumbnails

 

Information

You can solder

• * Steel
• * Stainless Steel
• * Copper
• * Brass
• * even Aluminium (but the solider is expensive and hard to come by)

If you cover or fill the inside of any solder item it will make any repair that much more difficult.

There are various types of solder, some cheap, some with better vibration strength. Best to go cheap as that will be more common in places where you may need a repair.

Failures on most things occur near the ends - you can strengthen the ends by putting another short length of tube side the first. You could solder it there too (to further increase the strength) provided you are not going to brazed or weld it.

Copper is heavier and more expensive than steel. For those reasons most people use steel. Copper can be tempered using heat (just like steel) to make it 'hard' (or stiff in non techinical terms).

The plumbing joints that include the solider will be as strong as those without, they are just more expensive (but reduces the labor cost so cheaper for people paying for labor, and you probable cannot get thoes without solider any maore anyway).

So, would it be possible to use self-soldering copper joints with mild steel tubing? Or would some strange reaction occur (like mixing steel and aluminium)? That might be the simplest solution for the incapable-of-welding.

The perk to copper pipe is that it's easily available, soft enough to bend without tools, cuts easily and there are ready made joints available. If nothing else that makes it very useful for prototyping, more useful than the plastic conduit I've used in the past as it can actually bear some weight which means you can test hang, and even ride with, panniers.

Then once we're happy it shouldn't be too hard to take the copper and get a steel version welded up.

Chris: your image of the throw-over plastic rack...



...takes me right back to my square one and thoughts on semi-rigid panniers. Unfortunately I'm one of those people who can see something in their head, but really struggle to translate that into a sketch. I could make one, but draw it? Do you have any more info on it? Type of plastic used etc.?

__________________

Phew, didn't think this would get such a debate going! All very interesting.

Yep. If that were a British website they'd be called Yorkshire fittings, which are used on my rack. Maybe, like many things 'old', that name's disappearing. Just need flux as well to make the joint.




Yes, that was in the back of my mind when considering whether to keep this rack. If it did split or crack, and the tubes were empty, repair would be simple. But filled with resin? It may be impossible. Other than wrapping material round the outside - hence my try-out with the fittings sawn in half and clipped around the joints as in the photos above.
But while the doubt was in the back of my mind, I kicked it right out and just got on with it......



Yep, you can still get those in builders merchants in the UK. The two mentioned above, split and clipped round 2 joints, are that type.



Yes, I've seen on the web just such a thing. Maybe it was on the HUBB? But it's out there somewhere, with instructions for construction.

Must go now, have an HU Mendip meeting to go to... and there's a big yellow round something in the sky!

__________________
TTR250 - London to Cape Town

Yes - good to revive this interesting thread and get some ideas out.

Not heard of that being done, and even filled with resin I think the relatively soft copper joints would be exceeding weak alongside the stiffer steel. You'd want a well cubed structure, rather like this OTS rack

The strap-on rack - it was at least 15 years ago, I think he bought my Funduro. All I know is it was a sheet of PVC some 10-12mm thick.
See this youtube bending vid.
Now I think about it, it's not the 'soft' plastic of chopping boards or rotomolded kayaks, but probably 'hard' lexan-like acrylic (I don't actually know what these words mean, but I know what they refer to) like the stuff we use to make windscreens. That is more brittle when thin and also actually quite heavy, but I reckon at 10-12mm thick would be quite hard to break. Looking again at that rack, he did a very nice job. I might round off the front edge a bit.

I must say that (today) I'm all fired up by these hex-key joints on ebay. Certainly stronger than copper. However...*

I've screenshot a number of them which I could visualise in assembling a rack - the usual elbows and Ts. The tricky bit is attaching pipe ends to the bike without doing the 'crush and seal' mentioned earlier, but some clamp types could be drilled and adapted to take a chunky bolt to the subframe.
And where the hex key force couldn't be expected to resist tension - such as downward loads on a platform base - you can just drill through it to use a regular nut and bolt, as well as glue.

I will probably go with 3/4 steel ECT mentioned earlier as it's dead cheap and comes galv/painted, but any tube, even hardwood doweling using wood screws instead of hex, works with those joints, I imagine. If I had clocked them earlier I would have done it by now.

* Added: ... I just received the clamps and they are for 1 1/8" OD tube with a 3/4" bore. I mistook those for the clamp dims not the pipe to fit them. What does the pipe bore matter? Thinking about it it does as the hex screw needs a thick-walled steel pipe to resist crushing while securing tightly. And of course their recommended 3/8th thick steel pipe of 1 1/8 OD will weigh a ton! I thought about trying to recover my mistake by considering wooden poles (28mm) or thick, 29mm OD ally tube, but the fact remains these cast clamps are hefty - 2-300g each? - way OTT for bike racks. Another flaw is that the overlap from hex point to max insertion is only 10mm - fine for a handrail or static structure, not so good for a moto rack. Drilled through bolts would be needed. So forget that idea...

The hex-key/scaffolding joints are cast and therefore brittle. They might be so massive that this won't matter, but hit one hard enough and it will shatter, usually where tapped for the grub screw. The field repair would be epoxy.

Copper would bend if you dropped the bike but could of course be bent back to shape. Epoxy filling would stop it crushing. Field repair could be solder or epoxy or a new fitting.

Wood is a great idea but takes skill. I designed a sidecar body in wood, basically copying aircraft techniques deHavilland used up into the 1950's. Light, strong and simple to repair with more wood or fibreglass. The trouble is that to do it properly you need to make forming jigs to hold it and the right temperatures to get the glue to cure as you form the laminates. You could also get in trouble in warm climates with the glue failing as the layers expand. The results could be first class, but bolted channel only requires hand tools and welded tube at least leaves me with something I might use elsewhere or can e-bay. The sidecar body ended up as bolted, rivetted and bonded aluminium sheet and angle (more Vickers than DH) and worked well, but a box not a rack.

Plastics wise you want something more like a Nylon or PVC. Lexan type stuff shatters and cracks when placed under enough load or the wrong temperatures. Again, it's jigs to form it accurately, the one in the picture I would guess was heated and draped over a former. The bottom angle could do with a bigger radius maybe? If drape forming, a spoon shape like the old plastic canteen chairs is stronger that the shape in the picture which is more like what you would do with laminated wood.

If you want to mess about with tooling, you could also look at glass or even carbon fibre. Your rack could be bullet proof!

Andy

Being a chippy by trade, I will one day have a go at a wooden rack just for a laff. I had even thought about knocking together a whole bike out of sticks.

For racks, I'll stick to good quality steel tube (it's only twice the price of poor quality stuff) and either Mig or Tig welding.

Seriously though, if anyone wants a rack making, give me a shout. I'll do mate's rates on the first one for a given bike. I will need the bike for a day or so.

Here's some pickies of the one I knocked up for my "S"

It'd be a little stronger made as a one piece but I wanted to be able to loose the pannier racks and just use the carrier. I did a little trip with this set up, 2500 miles including some trail riding in the Pyrenees whilst fully laden. The only thing missing to make it perfect are some strap loops on the top rack.
The one I'm making for my "E" will be a little different because the bike doesn't have a full subframe or rear pegs

Attached Thumbnails

 

 

 

That heater in the video is ok, but they show it being used on acrylic plastics. They are brittle.

I'd think it was grey in colour? In that case it is PVC. This stuff is not as brittle as the acrylic...

[yes, plastic rack was grey so = softer PVC. CS]

For the home workshop, you can bend PVC like sheet metal ... it will go off - white in colour - when bent too far... Before it gets to that angle .. heat it! That relives the stress and you can continue bending in successive stages to what ever angle you want. The thicker the sheet the less angle you can bend before requiring heating - say 10 to 15 degrees would be of for a 10mm sheet.
Heating? Use a hot air blower ..or a hair dryer...



Many different ways to make things

The two I prefer are

a) easily bent – if it is hit it bends ..and I can easily bend it back. Will work harden and fracture if bent too often.

b) Strong enough to support the bikes weight + me + luggage. Impossible to bend back unless you hammer it (and probably need heat as well).

I've built things both ways – each has it advantages. One I don't like is part way between the two - bends frequently and hard for me to bend back, try to aviod this

And here it is.... at the Mendip HU meet, the day before yesterday.

How simple can you get? And it carries a rucksack/pannier as well!

There you go.

__________________
TTR250 - London to Cape Town

Another great one for the collection.
Have to say though, I think twin shocks help with such minimalism.

I did something similar a couple of weeks ago to keep the bags out of the wheel, but didn't waste effort on jubilee clips ;-)

Attached Thumbnails

 

Thinking about racks for soft bags I reckon we can junk the tubular hoops which unless you can weld are a right PITA to make. Given that soft bags often have rigid backs why not make the rack with a plate instead? I'm thinking either 2mm aluminium or nylon like the Kriega Overland set-up.

You could probably use something like these clamps to attach tubular "legs" both to the plate and also to the bike.





Found HERE and HERE. The easiest way to attach a bag would be to have something like an upside down pocket which simply drops over the plate with a strap at the bottom to hold things tight.

I've thoughts on bags but maybe that's for a different thread?

__________________