rpenmanparker 

EDIT: I can't believe I spelled "there" as "their". Shame on me!

Here is what I don't understand. Take a look at post #2 in this BF thread:Reynolds 725 Tubing. Quality stuff?

Look at the chart of available Reynolds 725 tubes. Now 725 is essentially the same as the much-ballyhooed 753 of yesteryear, heat treated basic tubing that ends up with about a 1/3 increase in strength compared to the starting CrMo tubing it is made from. The difference is that 725 starts with 525 CrMo whereas 753 started with 531 MnMo tubing. But very much the same result.

Notice that the array of tubes that are offered are essentially the same as what has always been available in 525 and 531 tubes, i.e. no especially thin, light tubes. Where are the really thin tubes? The 0.8/0.5/0.8 tubes were always available in plain 531 (and Columbus as well) as the SL version, so that is no big weight improvement. Only one or two tubes out of a long list for each type is thinner than normal like 0.7/0.4/0.7.

Why go to the trouble of increasing the strength over CrMo if you aren't going to make lighter tubes out of the improved material? The two steel versions in the same tube specification will ride exactly the same, so what is the point of the higher strength steel. I am pretty sure if you had a similar chart for 831, you would see much the same thing. I know I have seen catalogs from tube suppliers that bear out that fact for 831.

My point is this. All the folks riding 831 and going on and on about how magical it is might be a victim of the emperor's new clothes syndrome. Unless they know for sure they are riding especially specified light gauge tubes, it is highly likely their bikes aren't any different than if they were made from 531C or 531SL tubes. Big whoop.

And even if the lighter tubes are used in a bike, why are so many more standard tubes offered than the lighter ones. If you don't need the extra strength, shouldn't you just use 525 for a standard tube and save the money?

Funny thing is, I would love to be wrong about this, but I can't figure out how that would be the case. Anyone?

fietsbob

You still have to join them .. so the Butts cannot be too thin wall ..

oversize diameters increase the strength without boosting the Wall thickness ..

rpenmanparker 

Wut? Are you saying that no bikes are made with thin-walled tubing? If that were true, there would be no point to even having specialty steels like 853. As it is, one has to wonder why the vast majority of the available tube configurations offered in such expensive and esoteric steels are the same ones that have been available forever in simple CrMo and MnMo. If you are going to have the thickness, you don't need the higher steel strength. If you are going to have the higher steel strength, you don't need the thickness. Why the insistence on doubling up? What is the point?

fietsbob

"Thin" has a number what do you have in mind? pretty "normal" Butt say 0.9 centers of 0.7?

in a 9/8"/28.6,, OD seat tube that thinner number on the top, leaves your 27.2 seat post fit.

26.8-(0.7x2)1.4=27.2..

if you want to be fussy Take it up with the Pro who will be building your frame Just for you alone .

and expect to pay them what they ask.

rpenmanparker 

Bob, I don't know how this has happened, but we are clearly engaging in two very different conversations. You're having one, and I'm having a different one. Best to just let it be.

McBTC

Steel is way passé but, 853 is magic~

Jarrett2

Are you asking why offer the same thickness in 853 as you do in 520?

JohnDThompson 

Ishiwata's "Alpha" tubing used 0.6/0.4mm walls, but that's about as thin as I've seen. Dents become a real concern with these extremely thin wall tubes. Alpha was thin enough that you could actually dent it with your hands with a strong squeeze.

fietsbob

What is 'advanced materials' to your mind ? Beryllium? carbon Hexcel L https://www.hexcel.com/

Magnesium is old hat by Now..

As JDT is pointing out there are Physical limits to wall thicknesses for practical Purposes

the Light Aluminum Trek Domane frames dent pretty easily Too.. I assume these are no different in that regard

https://www.trekbikes.com/us/en_US/bi...nda-alr/c/B212

rpenmanparker 

That is one of the questions, yes. 853's only contribution is the ability to thin out tubes made from it. Why would you spend more for a thick tube than you had to.

rpenmanparker 

High strength steels and steels treated for high strength.

rpenmanparker 

How so?

Jarrett2

Are you saying a tube of 853 would be the same weight and strength to an equal size tube of 520? Not sure what you are getting at.

rpenmanparker 

I'm sure that's right, but how then do you take advantage of the strength of 853 to lighten a steel bike?

rpenmanparker 

Of course that is what I am saying. And it would feel the same too. Not understanding that is what causes so many folks to throw money away on expensive tubing to no purpose.

fietsbob

I think this is more an OCD problem, by now .. You really want Unobtanium..

McBTC

There's no butts about it. I'm not too blind to see...

Jarrett2

So you're suggesting that frame builders would purposely choose a more expensive, but also heavier tubeset to build a frame from just to trick a buyer into thinking he got a thinner tubeset? Well... I suppose that is possible

As many say, there is a point at which you have to put some amount of trust in a frame builder. I guess unless you show up at their factory with some digital calipers... this would be one of those times

rpenmanparker 

You are not understanding this conversation very well at all.

rpenmanparker 

No. Not at all. I'm asking what is the point of offering all the same tubes in 853 that you offer in 525? They weigh the same in either material. It is known the 525 tubes are sufficiently strong by virtue of their greater wall thicknesses. Why do you need to overspend for the same tubes in 853 when the 525 tubes would do the job? Why not limit the 853 selection to those thinner tube gauges that the 525 isn't strong enough for? All those thick 853 tubes aren't offered for no reason. Some builders must be using them. And IMO those people who are using them are wasting the customer's money, just selling them on the imagined virtue of a complete 853 bike when partially 525 would be just as good. Now if you want all tubes to be the thinnest possible, of course it must be all 853 or similar. But then that whole list of thick tubes I referred you too would be there for no reason.

unterhausen

Did the OP somehow ask for free association and I missed it?

I suspect that even in the high strength steels, .4-ish is as thin as they feel comfortable drawing the tube. The heavier gauges are for when people want to build a stronger frame, for example a touring frame. Or for big people. For that matter, some of the CE testing requirements for frames are hard on a steel frame, so maybe that's the reason these higher strength tubes are available. Production bikes are often built heavier out of (possibly undue) caution, and it seems that there are 853 production bikes out there.

Jarrett2

I think that's pretty common. My Jamis has 853 main tubes only. Not sure what the rest is. Probably 725 would be my guess since they are heat treated, but not air hardened.

Ultimately, a frame builder can do whatever they want. They can say its all Reynolds and use a mix match of any supplier. They can say all True Temper S3 and slip an OX Platinum chain stay in there. Who would know?

There are other tells that would likely stop this sort of issue. If two different builders are in the business of building OX Platinum frames and one builder's frame routinely comes in at 3.7 lbs and the other routinely comes in at 5.2 lbs because he's slipping in some straight up 4130 in there, which builder will get more business?

I like Rodriquez's stance on this:
Honest bicycle weights

It reminds me of this $6000 2016 carbon fiber bike I saw on the scale recently:

rpenmanparker 

Good points about the heavier rider or touring frames. I did think of that and it is sort of like Columbus SL and SP both being made from the same alloy, just different gauges. It just seems strange that most of the tube configurations offered for 853 are for those special cases requiring heavier gauge AND higher strength steel. The whole point of 853 tubes is light weight (AFAIK) yet most of the tubes offered in the product line aren't consistent with that goal.

taras0000

Don't just look at the tube thicknesses, but look at the butting profiles as well. You'll find that as you go higher up the scale, the gauge thins out, the butts get shorter, and the tapers longer, and/or the thinner gauge gets longer. Some tubes also have a double zone butt profile. I'm not going to do the calculus on this, but I'll say that you just might end up with a lighter tube overall.

631 tube @ 25.4mm x 600mm long has 0.8/.05/.08 wall thickness, and a butt profile of 100/50/300/50/100mm.
725 tube @ 25.4mm x 600mm long has 0.8/.05/.08 wall thickness, and a butt profile of 85/40/330/40/85mm.
853 tube @ 28.6mm x 600mm long has 0.7/.04/.07 wall thickness, and a butt profile of 40/50/350/50/110

Found at - https://www.torchandfile.com/assets/i...ist%202014.pdf

The higher up the scale, the more choice you have as well when it comes to diameter, wall thickness (looks like they are thinning them out more), and butting profiles. This should allow the frame builder to not only build a lighter frame, but a stronger one as well. It also gives them much more control in being able to fine tune the ride quality of the frame.

The other thing about wall thickness and oversize dimensions is suitability. Steel is strong, but it is also heavy. Oversizing is the best way to stiffen a frame tube, but with steel, you can only take this so far before you start to incur a weight penalty, along with walls that are too thin. Nobody wants a heavier bike with fragile tubes. In this respect, it is better to go with a different material if those are your goals. I can have a super stiff track bike built out of aluminum, one that will be much stiffer than a steel bike, and still have it be lighter. Because of Aluminum's density, the walls will still have sufficient thickness to not be too fragile. To try and offer tubes in steel that approach this compromised overlap would be futile, as no one would use them.

unterhausen

I'm pretty sure I have seen stories of 853 breaking on loaded touring bikes, so maybe it's not a bad idea to go with heavier gauges.

eta: I hate short butts, I cannot lie