Ti tubing - straight gauge or double butted?
Comments
-
"Obviously the double butted tubing is more expensive, but why?"
Because it requires at least one more stage in the production process and at least one more (presumably quite expensive) machine tool. I assume that, like stee ltube sets, Ti plain gauge is subjected to pressure and by way of mandrels (shaping plugs/rollers is how I imagine them) has the wall thickness varied at one or more points.
I guess that in theory butted gives greater "compliance, comfort" call it what you will. Whther or not it does so in practice depends IMO on many other factors unrelated to the MATERIAL.d.j.
"Cancel my subscription to the resurrection."0 -
Please elaborate meagain, this is interesting0
-
Starters (CC Sheldon
"Thicker at the ends. Said of spokes and frame tubing. (Butted spokes are also called "swaged") Butted tubing is usually made with a constant outside diameter, but thicker walls at the ends. The idea is to make the part stronger at the ends, where the stresses are greatest, and lighter in the long middle section, where stresses are less.
Some writers have objected to this term being applied to spokes, and maintain that "swaged" is more correct, since the operation that produces a butted/swaged spoke is one of thinning the middle, not thickening the ends. For some reason they don't generally object to the use of "butted" in reference to tubing, though the process is also one of thinning the middle, not thickening the end. This objection is based on a misunderstanding of the origin of the origin of the term "butted." "Butted" means having a butt, i.e. a thick end, and has no reference to the means of fabrication. "
See if I can find a tech description - despite having many years ago worked in a Tube Investments machine and press shop an engineer I am not!d.j.
"Cancel my subscription to the resurrection."0 -
d.j.
"Cancel my subscription to the resurrection."0 -
Well I'm not an engineer at all mate so any info is apprectiated. Thanks meagain.0
-
Machining titanium is not easy either, apparently. I don't know the details, but a mate of mine works for Airbus, and they use titanium in their wings, and he said that they have to take all kinds of precautions against things going wrong while machining, which are a doddle for steel or aluminium. Making tubes of titanium is hard enough. Machining worse.0
-
just bumping this to get some more opinions guys0
-
giant mancp wrote:just bumping this to get some more opinions guys
I was looking for a definitive answer on the quality of one versus the other. In asking around I formed the view, rightly or wrongly, that it was more about the skills & workmanship of the welder than the process they used ie a double-butted that is mass-produced is not necessarily better than straight-gauge that is given care. Double-butted is often seen as stronger and lighter but if you the builder knows the material well they can produce effects without just making a binary choice on process. Just my perception, interested to hear what others think.0 -
The frame builder cannot alter the characteristics of the TUBING. And I don't see that the quality of the welding has much effect on anything other than aesthetics. The way in which the tubes are brought together, angles, lengths etc is a different matter - and that brings the argument back to .....is the material per se (alu, steel, carbon, ti, plywood....) of any relevance?
I guess that the main purpose of "butted", single, double, triple, whatever, is weight saving, ideally without any loss of strength.d.j.
"Cancel my subscription to the resurrection."0 -
meagain wrote:The frame builder cannot alter the characteristics of the TUBING. And I don't see that the quality of the welding has much effect on anything other than aesthetics. The way in which the tubes are brought together, angles, lengths etc is a different matter - and that brings the argument back to .....is the material per se (alu, steel, carbon, ti, plywood....) of any relevance?
I guess that the main purpose of "butted", single, double, triple, whatever, is weight saving, ideally without any loss of strength.
You are of course right about the tubing. However, in the context of the OP's question single gauges can ride better than the butted option from the same manufacturer. I just think there is a value judgement implied by the OP that cannot be answered by simple scientific reason of the tube/materials/process nature and that it is false to think butted is better across the board. The questions are surely a) how does the ride compare and b) if the ride is at least as good on butted is the gain in ride + the weight saving worth the £££.0 -
"it is false to think butted is better across the board"
Agreed. I suppose it would be everything else being equal, but then it never is!d.j.
"Cancel my subscription to the resurrection."0 -
Hello forum !
Just thought I try to clear up some of the questions you are chatting about. In terms of the process to form straight gauge and double butted tubes there is a number of strategies tube manufactures deploy. Without boring you all to death, basically seamlessly drawn tubes can be formed in a single process either to straight gauge or double butted. Some factories will produce a straight gauge tube and then reprocess it to butt it (various methods can be used to achieve this). There are various treatments (involving heat in various atmospheres) that change the structure of the material and enable designers like me to tune the properties of a given tube. These treatments can be done (and re-done) at various points along this process and also after welding in some cases too. The processes involved in forming the tubes (straight gauge or butted) will dictate the final properties of the material. After the tube is formed, subsequent processes can be used to tweek the properties further. This enables us to substantially change the properties of 3al, 2.5V ti. And other alloys of Ti further into the Beta phase can be changed considerably more. (such as 6al, 4V)
And as you have already stated you can then use different size tubes, different thickness of tubes, different tube shapes and different angles to define the final ride of the frame. Another parameter that hasn’t been mentioned and never published is the position, and length of the “butted” section. i.e where the thinner tube is and how long it is. In theory you could produce a tube with 10mm of thinner wall thickness somewhere in its length and say its double butted, yet its ride properties will be different from the same tube with 500mm of thinner section.
If your interested in this stuff, I can expand upon it in one of my tech blogs
http://www.sundaybicycles.co.uk/ssblog.php
hope this is of some use !
Iain0 -
My plain guage Airborne Zeppelin is like riding on a carpet of air.0
-
"hope this is of some use ! "
Yes, thank you! Our (well, mine) laymen's thinking starting to run out of steam I think!d.j.
"Cancel my subscription to the resurrection."0 -
Sorry if I’m making things too confusing. I think the take home message is that the material can be changed considerably so that even for a given straight gauge section the material properties can be changed a fair bit. Double butted certainly rides differently than the same spec material that is straight gauge, but both of them can be altered to an extent that noticeable riding characteristics are altered which muddies the issue !
In terms of the weight issue, double butted will obviously be lighter than straight gauge assuming the “thick bits” are the same thickness as the straight gauge and the thin bits are thinner which isn’t always the case !
Iain0 -
Thank you for your comments Iain, it does clear up some aspects of the differences for me anyway.
My original question, and one which I guess was obvious at least to me, is that would a frame with double butted tubing be a better smoother ride on the basis that such frames always seem to cost more than ones with straight gauge tubing.
For example, If you take the frames from your own Sunday stable, why does the Silk Road Pro (double butted) or your Monday's child (double butted) cost more than the September which as indicated on your web site, is straight gauge. Is it the different geometry and race orientation of these models, or indeed the work involved. Or a combination of these.
Putting the techical info aside for a second, what i wouldn't want to do is spend money on a straight gauge frame and regret not going for a double butted frame and missing out on a superior ride. I guess a test ride or two will clear that one up.
Thanks again.0 -
"Sorry if I’m making things too confusing"
Nope, not at all.
"I guess a test ride or two will clear that one up. "
But only if ALL the other components are identical and you follow exactly the same route in exactly the same weather conditions.d.j.
"Cancel my subscription to the resurrection."0 -
"would a frame with double butted tubing be a better smoother ride on the basis that such frames always seem to cost more than ones with straight gauge tubing. "
It might - it might not! Not sure that any direct (or even indirect) correlation between cost and smoother ride.
On reflection, delete "Not sure", insert "Absolutely certain".d.j.
"Cancel my subscription to the resurrection."0 -
Ok, all things being equal, a double butted frame is likely to be lighter and have a different ride. Its difficult to summerise the ride feel of well designed double butted frame, but often they feel a little more refined, you feel slightly more in touch with the road, and livelier. “smoother” can be obtained in various ways but we use straight gauge tube to isolate some of the feedback to make the ride smoother just as we manipulate double butted tubes to do the same thing. Its two different paths to arrive at a similar point, and both have pros and cons.
I appreciate I am being a little vague with the ride feel, but the reality is that it is quite possible that a double butted frame from manufacture X could be less comfortable than a straight gauge from manufacture Y or vice versa. In other words, to be sure, you need to ride a few of the frames on your radar and see for yourself which suites your needs or be clear what you want and then take advice as to which make and model will suit you best.
In terms of our range and the associated costs, these are due to a combination of factors which indeed includes the additional cost of the double butting process (which are substantial). The “pro” and “Mondays child” have machined 6al 4v headtubes, cnc replaceable dropouts and a number of different tube profiles all of which have cost implications. The Mondays child also has an asymmetrically butted rear triangle. In addition various treatment processes are used on some tubes to augment their properties. R and D costs also need to be added to the equation. All these points add up to arrive at the final costings. The products in our range are not better than each other, instead each is designed to do a certain job, and suit a certain type of person, and have a specific "feel". The technology, R&D and manufacturing costs to achieve each of these are reflected in the final costs.
In terms of the specific ride characteristics, the “pro” is very comfortable and the Mondays child very harsh. The September is a little red herring in this conversation as it has longer chainstays and very different geometry to suit its end use which will affect its “feel” in addition to the fact its straight gauge.
Iain0 -
Thanks Iain for your help0
-
Iain Roche wrote:I think the take home message is that the material can be changed considerably so that even for a given straight gauge section the material properties can be changed a fair bit. Double butted certainly rides differently than the same spec material that is straight gauge, but both of them can be altered to an extent that noticeable riding characteristics are altered which muddies the issue !
So you're suggesting that you can alter the ride characteristics by changing the material properties through some sort of heat treatment process? What inherent property of the ti is it you're altering through the heat treatment?0 -
Yes. 3al 2.5v is a near alpha material so its response to head treatment is more limited than ti alloy who’s microstructure is more in the beta phase. That said we are able to change the properties of the material by using various “treatments” using heat at various temperatures, exposure times, cooling rates and in differing atmospheres to alter things such as stiffness. However when you improve one property you usually loose out on another, so there is a great deal of skill and technical know how involved it getting the balances right.
Iain0 -
Iain Roche wrote:Yes. 3al 2.5v is a near alpha material so its response to head treatment is more limited than ti alloy who’s microstructure is more in the beta phase. That said we are able to change the properties of the material by using various “treatments” using heat at various temperatures, exposure times, cooling rates and in differing atmospheres to alter things such as stiffness. However when you improve one property you usually loose out on another, so there is a great deal of skill and technical know how involved it getting the balances right.
Iain
I guess I would rather have that balancing act done well than a butted frame treated shabbily. Plus it is nice to know there is skill in the craft for some reason - probably the pricer tags
0 -
How much difference to the stiffness are you able to make? Nothing I've found suggests any normal treatment making more than 5% difference in the Young's Modulus of any form of titanium, which I'd suggest would be pretty much undetectable in the ride.Iain Roche wrote:That said we are able to change the properties of the material by using various “treatments” using heat at various temperatures, exposure times, cooling rates and in differing atmospheres to alter things such as stiffness.0 -
is a 5% increase in stiffness negligible ?
That said, its not simply a case of doing these treatments to just increase stiffness (we may do some to reduce it for example!). Instead its one of the tools available to us to tune the way the material behaves under certain conditions, some of which will effect ride.
But if the same material is stiffer, we may not need as much of it.
We are just about to undertake some perception studies with different stiffness frames (to the same design) so i'll let you know !
Iain0 -
Ian
Nothing seems so poorly debated in frame discussion as the topic of 'stiffness' and yet both vertical and lateral stiffness are relatively simple for any competent frame manufacturer to measure using simple load/defletion rigs.
'Perception' is, of course, important to calbrate the meaning of measurements, but is not reliable on its own as there are so many other factors, particularly wheels/tyres and contact poinrs that can have a greater individual or colletive impact on the riding experience. Witness the recent C+ test of a bike containg Flax in the frame composite. Changing the wheels had a dramatic effect on the ride quality, but the tester still concluded that Flax was new magic ingredient!
One of the great advantages of plain gauge Ti is that it is reasonably resistant to accidental damage from baggage handlers, etc, and therefore a good choice for a bike that is being transported regularly.0 -
I agree it is very poorly understood by many. Rig testing is possible, but not as simple as (i) initially thought. Simple testing to benchmark bending stiffness’s is possible (although they don’t always translate directly to “in field” results for various reasons). It is also worthy of note that we have found that static load deflections are not representative and a dynamic loading cycle is required.
Agree again about the misinterpreted “perception” of feel due to miss guided opinion / other factors causing multifactorial responses resulting in difficulties relating said changes to the frame.
This is why this work will be conduced under scientifically creditable conditions and the perception studies carried out in accordance to the excellent published perception study methodology by Davies, G et al (2003) amongst others. This methodology has been published in pear assessed international sports journals and is widely recognised as the current benchmark in perception study.
Iain0 -
It's virtually undetectable by the rider - you'd need a very well calibrated rider. In any case, I doubt you're getting anywhere near that much change - as you commented, the response to heat treatment of 3al2.5v is much more limited than that.Iain Roche wrote:is a 5% increase in stiffness negligible ?0 -
Possibly. I used speech marks around “heat treatment” because we use treatments involving heat that may not come under the textbook definition (i.e we are not altering the phases as discussed previously) yet these treatments are used to control (relieve) the amount of internal stress in the material as a consequence of tube production and subsequent manipulation. And the result of this is a change in some physical properties.
Iain0 -
Sounds like perfectly normal frame heat treatment, which is indeed a good thing as it improves the durability. However I'm extremely dubious that it makes any difference at all to the ride, as to do that you would have to be altering the phases (or at least changing the microstructure, which isn't necessarily exactly the same thing).Iain Roche wrote:Possibly. I used speech marks around “heat treatment” because we use treatments involving heat that may not come under the textbook definition (i.e we are not altering the phases as discussed previously) yet these treatments are used to control (relieve) the amount of internal stress in the material as a consequence of tube production and subsequent manipulation. And the result of this is a change in some physical properties.
Iain
Not having a go, and trying desperately not to be rude, as I appreciate your contributions here. However I think you are pushing things a little bit by suggesting that your heat treatment has similar effects on the handling/ride as the difference between plain gauge and butted tubing. Of course effects of the same magnitude or greater than the PG/butted difference can be gained through the use of different tube profiles.
I shall desist in this thread from questioning how much real difference any of these factors actually make! :twisted:0
