Thorn heat treated tubing

[Smiffy]

I have a 2013 Thorn Raven, which has it’s frame made with Thorn heat treated tube, but the forks are made with Reynolds tube... Why would they use Thorn tubing on the frame over Reynolds ? .. How does the quality of Thorn heat treated tubing compare with Reynolds ?

[4leksander]

http://thorncyclesforum.co.uk/index.php?topic=13300.0

Thorn tubing is apparently comparable to Reynolds 725 (some more information in post above - see rualexander's attachment).

I would guess they could source material of same or similar properties cheaper and went with it.
It seems to be working both for customers and for Thorn.

[PH]

I'll have a guess at that and that's all it'll be, those who actually know why Thorn have made those business decisions are unlikely to tell us.
There's plenty of tube manufacturers, unless it's at the cutting edge it's a pretty straightforward manufacturing process, hardly changed in a century, though some of  the hardening and heat treatments are more recent developments. The different alloys of the various steels are public knowledge, though some newer variants may have current patents.   
So. why use Reynolds?  You know what you're getting, it's easy to make comparisons, it's a well known brand and these things add to it's perceived value - both original and re-sale.
Why use anything else?  Price? Maybe, if nothing else shipping British made tubes to Taiwan to ship back again will have a cost.  Specification - off the shelf tubes have a limited range of sizes and profiles, if you're buying enough you can specify your own, Reynolds will do this as well, though it's likely to be more economical elsewhere.
Quality wise there's no reason why a tube of the same alloy made to the same specification will be any different from one manufacturer to another, it'll all be down to the quality control.  If Thorn are happy with that so would I be, if I wasn't I wouldn't be buying from them.
I suspect a fair amount of decisions are made for marketing reasons, the Mercury is Reynolds top tier tubeset 853 (Not counting the stainless 953)I have no doubt it would ride the same without the Reynolds sticker, but would many be prepared to pay those prices without it? Reynolds heat treated cromo is 725, that's a rung up from many OTP touring bikes, given the choice between a Reynolds sticker for a none heat treated (525, 631) or an own brand HT, I'd choose the latter.
It's easy to obsess about the numbers and there's nothing wrong with that unless you give it more importance than it deserves.  All steel tubes of the same dimensions will feel the same, regardless of the alloy used.  The different properties that alloys provide will enable tubes to be manufactured to different dimensions, such as thinner walls, though not all these "improvements" are desirable on a touring bike.  In the end if you get a bike you like, it has a frame with a lifetime guarantee, then the rest is just interesting* (Or not) chit-chat.

*Reynolds specifications are worth reading for those that way inclined
https://www.reynoldstechnology.biz/materials/steel/s-853/

Completely off topic, but if anyone doubts that cycle tubes are not cutting edge metal technology have a read of this
https://www.theengineer.co.uk/rolls-royce-single-crystal-turbine-blade/

[Smiffy]

Many thanks PH , that was really interesting.

[Andre Jute]

Excellent post, PH.

All steel tubes of the same dimensions will feel the same, regardless of the alloy used.

If wonder if that is always true. I had a Peugeot bike once, made of "manganese alloy", said to be the bee's knees, beautifully fillet brazed by a master craftsman, and priced like cutting edge technology. The thing rode so harshly regardless of which tyres were fitted, it wrecked my back for years. Only my physio loved it; she bought a new BMW to celebrate my bike crippling me. Either the tube diameters and wall thicknesses and butts were outrageously wrongly specified, or the alloy was hostile to bicycle use. At first I thought it was the designer that was at fault, but then I bought a Gazelle aluminium bike to replace it, and the ali tubes were bigger in all dimensions*, the tyres were comparable, and the Gazelle was a lot nicer to ride (even though in the end, when I also had a sublimely proportioned bike made from custom-drawn Columbus steel to measurements refined over half a century, I decided that ali was still too stiff and unyielding by comparison to a correctly specified and made steel bike). The only thing left to make the Peugeot so unacceptable was then the manganese alloy.

Not everything that is important about metals is in Timoshenko! As a lifelong audiophile I have sympathy with the more moderate believers in beneficial factors in certain metals that are not yet described by physics.

* In a celebrated (by hotrodders no less than factory design studios) book on the design of prototype cars a few years earlier, I showed how to design a chassis or even a monocoque without more than simple math in other metals or materials by analogy to an existing steel structure, so it was a conditioned impulse to look at cars and bikes comparatively, with a calculator clattering in the back of my head.

[macspud]

I seem to remember reading somewhere (can't find it now) that Reynolds fork blades are no longer used, as they had stopped using seamless tubing.

[PH]

Excellent post, PH.

All steel tubes of the same dimensions will feel the same, regardless of the alloy used.

If wonder if that is always true. I had a Peugeot bike once, made of "manganese alloy",

There's always room for doubt, but my money would be on the difference being something other than the material.  There are variations in elasticity between types of steel, measured as Young's Modulus, but they're a couple of percent, by contrast the difference between steel and aluminium is around 50%.
https://www.amesweb.info/Materials/Youngs-Modulus-of-Steel.aspx

I don't know much about manganese alloy other than it's hard to cut and used on prison bars and safes! I know it isn't magnetic, is it also rust proof? Not sure which of it's properties tempted Peugeot to use it.  Or could it have been marketing?  Plenty of steels contain some manganese but are still a carbon alloy.

[leftpoole]

I have a small number of Thorn Audax cycles including 3 Audax 853 (Reynolds). The frames of the later Audax are Thorn 858 but I have chosen at extra costs to have Reynolds 853 forks except 1 which has or will be having Carbon (for a change).
The Audax cycles using 858 Thorn metal ride fine and with the Reynold 853 forks give  extra comfort.
I used to own a Club Tour built with Reynolds 725, it rode well.
My own opinion is that costs were the major reason for sourcing similar material and that the option of Reynolds 853 for forks is to indulge customers such as myself (total madness when it comes to cycles). I think the Thorn custom drawn material is excellent and nowadays top end materials is what counts and not brand name.
I have other brand cycle/s which are built with Columbus and Tange. They ride just as nicely as and top end steel framed cycle (in my opinion).
Regards,
John

[Andre Jute]

Not sure which of it's properties tempted Peugeot to use it.  Or could it have been marketing?  Plenty of steels contain some manganese but are still a carbon alloy.

I think it possible that technical horizons expanding also played a part. Roundabout that time CNC laser cutters became available at reasonable prices, at least if you were a major manufacturer. I bought the bike directly from the importer (my local LBS got tired of me breaking bikes he sold me and demanding a new bike, so he told me to buy a good bike once and for all, off the top of the tree, and he brought the distributor down to see me, and I bought his best bike sight unseen). The distributor led me to believe the "mangailoy" was a big deal. The bike was also fillet brazed, unlike the lesser bikes in the same range, to show off the closeness of the tube fits. So probably a mix of new technical opportunities and, as you say, marketing. 

Whether that particular or generic manganese alloy is fundamentally rustproof I don't know for a fact. It's still running around under a series of successive owners and there's no instantly apparent rust on it, though the original paint is in a poor way after nearly thirty years.

[PH]

For anyone still interested, here's a of the tubes available from Reynolds, from 2017 but I haven't seen a more recent one.
http://www.torchandfile.com/assets/images/2017%20JAN%20PARTS%20LIST.pdf

You might notice that a popular wall thickness for touring type tubes is 0.9-0.6-0.9mm and for lighter road/Audax 0.8-0.5-0.8
Thorns touring tubeset is called 969 and the audax type 858.  Coincidence?  I don't think so

[Mike Ayling]

You might notice that a popular wall thickness for touring type tubes is 0.9-0.6-0.9mm and for lighter road/Audax 0.8-0.5-0.8
Thorns touring tubeset is called 969 and the audax type 858.  Coincidence?  I don't think so

On their product description document Thorn explained the 969 exactly as you state. No coincidence as I se it.

Mike

[B cereus]

From memory Peugeot introduced their own manganese alloy steel some time in the early eighties . As others have said,  although all steels have similar elasticity the more exotic alloys vary in their ultimate tensile strength. High tensile strength allows for less steel, usually in the form of thinner walls,  but is often combined with larger tube diameters to increase stiffness.

At the same time Peugeot engineers developed a method of fillet brazing that lent itself to mass production, and which they called internal brazing. From my understanding the method was dependent on accurately cut mitres which were achieved using milling machines. A doughnut ring of braze material was then inserted inside the mitred tubes which were then assembled using a jig. When heated using automated ring torches the braze material flowed around the joint by capillarity. I remember advertisements pictures of the time, and typically these joints had the majority of the fillet on the inside with just a narrow fillet on the outside.

[Andre Jute]

From memory Peugeot introduced their own manganese alloy steel some time in the early eighties . As others have said,  although all steels have similar elasticity the more exotic alloys vary in their ultimate tensile strength. High tensile strength allows for less steel, usually in the form of thinner walls,  but is often combined with larger tube diameters to increase stiffness.

At the same time Peugeot engineers developed a method of fillet brazing that lent itself to mass production, and which they called internal brazing. From my understanding the method was dependent on accurately cut mitres which were achieved using milling machines. A doughnut ring of braze material was then inserted inside the mitred tubes which were then assembled using a jig. When heated using automated ring torches the braze material flowed around the joint by capillarity. I remember advertisements pictures of the time, and typically these joints had the majority of the fillet on the inside with just a narrow fillet on the outside.

Wow, what a memory you have!
 
I'm going to leave my post above as firsthand experience of a bike I owned, but where my speculation about the technicalities of the production method differs from B cereus's recollection of printed materials at the time we'd do well to work with his version instead.

It occurs to me on reading B cereus's post that there is another explanation for the unfortunate ride of that bike: with a new material and a new jointing method, the designer simply didn't have enough experience of the materials and effects to specify the tubes in the right weights and proportions and, rightly, erred on the side of safety by over specifying them.

It was — except in motion, alas! — such a beautiful bike...

[PH]

At the same time Peugeot engineers developed a method of fillet brazing that lent itself to mass production, and which they called internal brazing.

interesting stuff - is that technique still used by anyone? Or did TIG welding take over as the most practical form of mass production.

[B cereus]

Andre, I'm not sure I've got the same confidence in my memory as you seem to have. I do remember reading a thread about the internal brazing technique over on the CTC/CUK  forum a few years back, but I couldn't find it again.

At the risk of drifting even further off topic I've been doing some digging on line and I found this excellent resource.

http://www.bikeboompeugeot.com/index.html

It appears that Peugeot called their in house manganese alloy steel HLE (Haute Limite Elastique)

http://bikeboompeugeot.com/Brochures%20USA/Peugeot%201985%20USA%20Brochure/Peugeot%201985%20USA%20Brochure%20Page%205.jpg

I also found this catalogue shot from 1982 of the fillet brazing method

http://bikeboompeugeot.com/Brochures%20UK/Peugeot%201982%20UK%20Brochure/Peugeot%201982%20UK%20Brochure%20Pg10.jpg

It mentions extensive use of Reynolds 531 as well as their own 103 tubing. 103 isn't the same as HLE and is I believe a basic high tensile carbon steel.