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853 vs. 631 steel??(9 posts)

853 vs. 631 steel??Elefantino
Jan 18, 2002 8:15 AM
Because I cut metallurgy class, I don't understand the qualitative differences between Reynolds 853 and 631 steel, particularly in large frames.

Any input would be appreciated. The third bike (actuallly the fourth, but I'm giving the OCR to my son) is on the horizon.

Mike
re: 853 vs. 631 steel??MJ
Jan 18, 2002 8:48 AM
if two frames were identical 853 is 'harder' and 'stiffer' than the 631 version - alot of touring frames are 631 based - there's not much weight difference if that's important to you - 631 has a reputation for lasting longer and being a more forgiving frame material (not as brittle) - 631 is also cheaper than 853

I'm not a metallurgust but had my builder explain all this to me when I ordered my cross bike last year - I went with the 631 FWIW but attribute the ride to the builder rather than the material
re: 853 vs. 631 steel??alpho
Jan 18, 2002 9:06 AM
853 is also lighter, more extensively butted, and heat treated.

853 is reynolds 'top shelf' tubing, whereas 631 is a bit lower in the chain, but still a great material.

if you were getting a steel racing bike/light chi-chi top-end bike, 853 is a logical choice. i dont think durability would come into play as a practical matter on the road. plenty of mountain bikes that have a reputation for taking abuse and riding like butter are made of 853 (independant fabrications comes to mind here).

if you are riding in harsh conditions or want bombproof durability at the cost of some weight, 631 is good.
re: "!'m not a metalurgist........."Rusty Coggs
Jan 18, 2002 5:28 PM
HFC...man did you get that right.Everything your builder told you musta turned to mush and dribbled out on the floor.What a friggin barge load of BS!! Translation....You don't know sheot about tubing! Both alloys are equally stiff, ...I won't waste my time on the rest of it,MR. 'know it all'.
From Reynolds...Zignzag
Jan 18, 2002 11:53 AM
http://www.reynoldsusa.com/prop/853.html
is a discussion of 853 and 631 steel. I think the difference is that 853 is air hardened so the ultimate tensile strength (UTS) is higher. The higher UTS allows for thinner, thus lighter, tubing.
re: 853 vs. 631 steel??Nessism
Jan 18, 2002 1:20 PM
It's my understanding that both 853 and 631 use the same metal alloy, or very similar, however 853 is heat treated whereas 631 is not.

The bottom line is that 853 uses a much stronger alloy which will allow the tubes to be made thinner. Thinner tubes will be lighter but more flexable. One nice thing with 853 is that it comes in a varity of thicknesses. With a lower strength alloy, that option does not exist.

For a large frame however, the 631 tubes may be OK. Large frames need stout tubes. If you need a thick tube to stiffen up a frame, there is no reason to spend extra money on the high strength alloy - 853 tubes are expensive.

How big a frame are we talking about here?
re: From strong racing(in part)Rusty Coggs
Jan 18, 2002 1:22 PM
853 is a stronger alloy then 631.180-210aksi vs 115-130ksi ultimate strength respectively. Both are air hardening,and 853 is heat treated.Both are equally stiff.853 by being stronger can be built into a lighter frame, and All ELSE being equal,that is the biggest difference.How the tubes are shaped ,butted and also otherwise dimensioned can make a significant difference in how the frame performs, especially in bigger sizs and with heavier riders. It's more than about the alloy.
re: 853 vs. 631 steel??kendoo
Jan 18, 2002 2:11 PM
And where does this Boron stuff that Bianchi uses fit into the steel frame picture?
Bianchi Boron tubingNessism
Jan 18, 2002 4:38 PM
I think Dedacciai makes the tubing for Bianchi. Nothing is published regarding the specs but it must be super thin to build up into the frame weights that Bianchi claims. I have heard a fair number of reports of breakage however which leads one to beleve that it is a little too thin for its own good.

Dedacciai makes some outragiously thin tubesets these days. The EOM 16.5 Extra Light tubeset is so thin that one of Dedacciai's main US distrubuters (Bringheli.com) is reluctant to carry it. I should guess that the Bianchi Boron tubing is a similar configuration.

In my mind this tubing falls into the questionable catagory or at least - limited application catagory.