4130 Chromoly vs. Reynolds 853 Steel

Can any of you explain the diffrence between the various steels used
for bicycles and their comparitive advantages? Example: A Lemond
Zurich (DF) boasts a Reynolds 853 sticker on the frame. It seems as
though all of the steel recumbents are 4130 chromoly. Thanks in
advance.

(Bobinator) wrote in
m:

Can any of you explain the diffrence between the various steels used
for bicycles and their comparitive advantages? Example: A Lemond
Zurich (DF) boasts a Reynolds 853 sticker on the frame. It seems as
though all of the steel recumbents are 4130 chromoly. Thanks in
advance.


IIRC,most Reynolds steels use manganese as the stiffening alloy, although
they do make a 4130. 4130 uses chromium and molybdenum. Butted tubing is
more difficult to come across in larger diameters and lengths that are most
oft used in bents. Straight gauge 4130 is readily available.Also, many
alloys have more stringent temperature restrictions for brazing or welding.
4130 is more forgiving than most. Reynolds 853 is recommended to be used
with lugged construction silver brazed methods. Recumbent lugs are a
bit difficult to find.(^: Here is more info on the subject, written by
people who know much more than I:

A good description of Reynolds tubings:
http://www.worldclasscycles.com/JACKSON-HOME.htm
and
http://www.desperadocycles.com/The_L...eel_Tubing_pag
e4.htm

and http://www.henryjames.com/tubing.html
and
http://www.phred.org/~josh/build/brazing.html
and http://www.waterfordbikes.com/models/const.php

happy trails,
rorschandt

Bobinator wrote:
Can any of you explain the diffrence between the various steels used for
bicycles and their comparitive advantages? Example: A Lemond Zurich (DF)
boasts a Reynolds 853 sticker on the frame. It seems as though all of
the steel recumbents are 4130 chromoly. Thanks in advance.

853 has a higher strength to weight ratio, has better fatigue strength
and stiffness (about 30% greater than 4130). 853 is still Reynold's best
steel. The joints actually gain strength as they cool. 853 cannot be
brazed, only welded.

Reynolds makes a 4130 called Reynolds 525. It's a general all-purpose
tube - less expensive than 853.

R2







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The reason recumbents are done in 4130 is that a the tubing shapes and
sizes of a diamond frame bike do not cross over to a recumbent... yet.
Diamond frame tubes are usually no longer then 2 feet. Some recumbent
frames require 4 foot lengths.
Diamond frames are fairly routine in their dimensions. In many cases,
paint is all that makes one brand different from another.
In recumbent land the frames are very different from one maker to the
next. Change the paint and you will still know where the frame came
from.
4130 is good, strong material that comes in many sizes and shapes.
Perfect for the small manufacture.
Speedy

Bobinator wrote:

Can any of you explain the diffrence between the various steels used
for bicycles and their comparitive advantages? Example: A Lemond
Zurich (DF) boasts a Reynolds 853 sticker on the frame. It seems as
though all of the steel recumbents are 4130 chromoly. Thanks in
advance.



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FWIW, interesting comment I saw posted recently on steel tubing:

"725 is Reynold's replacement for 753, it was introduced 4-5 years ago. It
is a Chromium-Molybedenum steel alloy that is heat-treated. Its non
heat-treated brother is 525 which is also the 531 replacement. 725 is a very
desirable tubing, said to be nearly identical to the famous but sadly gone
Tange Prestige tubing. Biggest advantage versus 753 is its heat tolerance.
Its low carbon content makes 725 easily joined with silver, brass or even
TIG welding, although it does suffer some annealing in heat effected area.
Most importantly for ride and durability, 725 has much better elongation and
ductility than air-hardened alloys thus maintains much of that resilience
that tubesets like 531 and 753 were most noted for. I would avoid 853/653,
Columbus Foco/Ultra Foco, Dedacciai 16.5 and True Temper OX Platinum/Gold --
these are in my experience rather "harsh or brittle" to borrow your
phrasing."


"Bobinator" wrote in message
m...
Can any of you explain the diffrence between the various steels used
for bicycles and their comparitive advantages? Example: A Lemond
Zurich (DF) boasts a Reynolds 853 sticker on the frame. It seems as
though all of the steel recumbents are 4130 chromoly. Thanks in
advance.

General rules of metallurgy:
Stiffness is a function of elastic modulus. Just about all steel
alloys have similar enough moduli that any difference would vanish
into the noise.

One should almost NEVER weld heat treatable steels, or any other heat
treatable alloy for that matter, unless you are prepared to re-heat
treat or accept the loss of strength in the base metal next to the
weld joint. The weld may meet the strength of the original base metal
but the heat from the welding will completely mess up the heat
treatment of the base metal next to the joint. Furthermore in thick
sections, nothing in bike manufacture is thick enough for this
concern, it is required to heat the metal to red hot to prevent
cracking of the base metal next to the weld joint. (Personal lesson
learned here is to never simply tell someone to get the joint hotter
than hell before welding unless you tell them how hot you think hell
is.)

Fatigue resistance and actual tensile strength is a function of the
alloy, but it is also a function of the heat treatment. Also, the
fatigue resistance of steels is relatively high. Minor changes can
seriously affect the fatigue properties of aluminum alloys because it
is is much lower, but steel is relatively tolerant. I'm not sure if
you'll see any real differences here in a practical, rather than
laboratory, situation.

If there is any real differences, you might see some effect in
corrosion resistance. An alloy that is tweaked to the limits of what
it can do will corrode faster than one that is working in the center
of its capabilities.

4130 Cr-Mo steel is used frequently because it is an old
well-characterized alloy. It's commonly available, easy to
manufacture, and in the kinds of section thicknesses you see in bikes,
easy to heat treat. If you were willing to pay what it cost to make a
custom titanium bike and end up with a steel bike, I could suggest
some better steel alloys that, if you were the kind of rider that
Fabrizio thinks he is, you might be able to detect the difference in
performance.

From a basic metallurgy standpoint only, the differences in alloys
means they can charge you more money because they use their "custom"
alloy rather than garden variety 4130. Racing strips would be about
as effective.

FWIW the frame of the late lamented Kingcycle was made from custom-ovalised
plain-gauge 531.

Dave Larrington - http://www.legslarry.beerdrinkers.co.uk/
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