Are bike frames soldered or brazed?

[Jeff Potter]

As far as I know bike frames are always brazed.

As far as I know you only solder plumbing joints with soft, well, solder.

I'm wondering if the term 'solder' has a place with any part of bike frame construction.

Thanks!

--

Jeff Potter
****
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[Rod Jenkins]

> As far as I know you only solder plumbing joints with soft, well, solder.
>
> I'm wondering if the term 'solder' has a place with any part of bike frame construction.

Brazing originally meant joining with brass, which is an alloy of copper and zinc, and has a melting
point around 900C depending on composition.

Soft solders tend to be alloys of lead, tin and other metals which have melting points around 200C.

The confusion arises from mid range materials which are sometimes called hard solders and sometime
silver brazing alloys. These are made from silver, copper, zinc and cadmium and have melting points
in the range 600C-800C. Depending on the alloy used these brazing alloys, when molten, can flow like
water, which is good for lugged frame construction or can be pasty which allows them to be used for
fillet brazed frames.

Bicycle tube steel alloys like Reynolds 531 should not be over heated, so the lugs and tubes are
best joined with a hard solder. These silver brazing alloys tend to be more expensive because of the
silver content. More modern steel alloys are capeable of withstanding higher temperatures and can
even be welded, which requires localised temperatures of 1400C or so.

So, soldering is a reasonable term to use in bike talk.

cheers, Rod

 

[Simon Brooke]

Jeff Potter <[email protected]> writes:

> As far as I know bike frames are always brazed.
>
> As far as I know you only solder plumbing joints with soft, well, solder.
>
> I'm wondering if the term 'solder' has a place with any part of bike frame construction.

Reynolds 753 frametubes have to be silver soldered as the material is damaged by being heated to
brazing temperatures. However it's no longer made, and the 853 which replaces it can be brazed or
even welded.

--
[email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/

do not sail on uphill water
- Bill Lee

 

[Ken]

Jeff Potter <[email protected]> wrote in news:3F99DA87.3E233926
@outyourbackdoor.NOSPAMcom:

> As far as I know bike frames are always brazed.

In addition to the "silver soldering" that others have noted, other non- brazing techniques include
welding, gluing/bonding, and mechanical techniques such as lugging and screwing.

 

[Phil Brown]

Sivler soldering is also known as silver brazing. It's just a lower temp brazing than brass.
Phil Brown

 

[Grenouil]

"Jeff Potter" <[email protected]> wrote in message
news:[email protected]...
> As far as I know bike frames are always brazed.
>
> As far as I know you only solder plumbing joints with
soft, well,
> solder.
>
> I'm wondering if the term 'solder' has a place with any
part of bike
> frame construction.
>
> Thanks!
>
> --
>
> Jeff Potter
> ****

May be a bit off topic, but I recently added downtube shifter bosses and top tube cable guides to my
old Ishiwata 022 steel frame using one of the relatively new(?) lead-free plumbing solders. These
melt at 415 degrees Fahrenheit, so quite a bit higher than 'soft' solder, and close to the melting
point of silver solder.

When I subsequently had the frameset powder coated I had to specify a bake temperature of 350
degrees, though, for obvious reasons - some powder coaters bake as high as 425 degrees or so.

 

[Carl Fogel]

"Rod Jenkins" <[email protected]> wrote in message
news:<[email protected]>...
> > As far as I know you only solder plumbing joints with soft, well, solder.
> >
> > I'm wondering if the term 'solder' has a place with any part of bike frame construction.
>
> Brazing originally meant joining with brass, which is an alloy of copper and zinc, and has a
> melting point around 900C depending on composition.
>
> Soft solders tend to be alloys of lead, tin and other metals which have melting points
> around 200C.
>
> The confusion arises from mid range materials which are sometimes called hard solders and sometime
> silver brazing alloys. These are made from silver, copper, zinc and cadmium and have melting
> points in the range 600C-800C. Depending on the alloy used these brazing alloys, when molten, can
> flow like water, which is good for lugged frame construction or can be pasty which allows them to
> be used for fillet brazed frames.
>
> Bicycle tube steel alloys like Reynolds 531 should not be over heated, so the lugs and tubes are
> best joined with a hard solder. These silver brazing alloys tend to be more expensive because of
> the silver content. More modern steel alloys are capeable of withstanding higher temperatures and
> can even be welded, which requires localised temperatures of 1400C or so.
>
> So, soldering is a reasonable term to use in bike talk.
>
> cheers, Rod

Dear Rod,

For the sake of the fascinated layman, could you be coaxed into expanding on the subject?

Have these modern steel alloys made brazing pointless, or is the welding a matter of cost and
convenience? Is there a practical difference in the strength of the joints? Can non-steel frame
parts be brazed to each other or to steel pieces?

Judging by your post, even random thoughts from you on the matter will be a pleasure to read.

Hopefully,

Carl Fogel

 

[Werehatrack]

On Fri, 24 Oct 2003 22:06:14 -0400, Jeff Potter <[email protected]> may have said:

>As far as I know bike frames are always brazed.

No. Welding is used at least as often, in fact far more often if you count the mass-produced bikes.
Lugged frames are still brazed or (preferably, in my opinion) silver soldered. Butted tubes may be
joined by various methods, depending on the maker's preference. I doubt that any aluminum frames are
soldered, although exotic solders exist to use with that material. (I keep a few sticks around for
emergencies.)

>As far as I know you only solder plumbing joints with soft, well, solder.

In much of the world, plumbing joints are now soldered with a material that is typically 97% tin or
higher, and with few other metallic fractions. This is due to the mania for reducing lead in
drinking water. This is but one of the vast number of types of soldering. Brazing is another form of
soldering. Silver soldering, which uses a material very similar to brazing rod except for the
presence of a small amount of silver in the alloy, is another. Soldering is the process of joining
two metal parts (which may be of dissimilar material) using heat and a third metal or a metallic
mixture which will flow and bond to the other two, sometimes requiring the use of a flux to
facilitate the bond. Solder does not have to be soft, or made of lead or a lead alloy.

>I'm wondering if the term 'solder' has a place with any part of bike frame construction.

Yes, absolutely. Just not with auto body solder (now largely unknown in any event, though used
for some lugged frames in the past) or plumbing solder (which used to be very similar to auto
body solder).

--
My email address is antispammed; pull WEEDS if replying via e-mail. Yes, I have a killfile. If I
don't respond to something, it's also possible that I'm busy.

 

[Jim Beam]

> As far as I know bike frames are always brazed.

absolutely not! t.i.g. welding is the commonest jointing method for steel tube these days.

> I'm wondering if the term 'solder' has a place with any part of bike frame construction.

yes, but it's more correctly termed "silver solder". as others have pointed out, it's a hard,
strong, but lower temperature jointing process than traditional brazing and is used on
heat-sensitive tube. there's plenty of info on silver solder on the web.

it's less relevant today because of the widespread use of air-hardening tube like reynolds 853. this
tube was designed to meet the needs of
t.i.g. welded construction, but it can also be brazed. if you /do/ braze it, reynolds specify using
traditional /high temperature/ brazing, _not_ silver solder, so that it triggers the
hardening process.

jb

 

[Peter Cole]

"Carl Fogel" <[email protected]> wrote in message
news:[email protected]...
>
> Have these modern steel alloys made brazing pointless, or is the welding a matter of cost and
> convenience? Is there a practical difference in the strength of the joints? Can non-steel frame
> parts be brazed to each other or to steel pieces?

A Keith Bontrager "rant" on the subject:

http://tinyurl.com/scc0

 

[Matt O'Toole]

"Jeff Potter" <[email protected]> wrote in message
news:[email protected]...

> As far as I know bike frames are always brazed.
>
> As far as I know you only solder plumbing joints with soft, well, solder.
>
> I'm wondering if the term 'solder' has a place with any part of bike frame construction.

Well, silver "brazing," as used in some lugged steel bikes, is actually soldering. In fact, they
called it "silver solder" back when I learned to do
it.

The difference is that while the brazing metal itself is structural, solder is basically just glue.
There's probably a gray area in between, so making the distinction is just picking nits.

Matt O.

 

[Phil Brown]

>Well, silver "brazing," as used in some lugged steel bikes, is actually soldering. In fact, they
>called it "silver solder" back when I learned to do
>it.
>
>The difference is that while the brazing metal itself is structural, solder is basically just glue.
>There's probably a gray area in between, so making the distinction is just picking nits.

Don't know what you mean by "structural." First, you can make a lugless frame using silver, it's
just hard and expensive. No brazing process, wheather using silver or brass, melts the base metal.
If it did it would be called welding. Any brazing process is akin to "gluing." And before you Jack
Taylor and English race car owners chime in the process the English call bronze welding is in fact
brazing. Phil Brown

 

[Simon Brooke]

jim beam <[email protected]> writes:

> > As far as I know bike frames are always brazed.
>
> absolutely not! t.i.g. welding is the commonest jointing method for steel tube these days.

Can anyone say _why_ welding is preferred for mass produced frames? I would have thought (perhaps
naively) that with tubes as thin walled as bicycle tubes, welding would call for even more skill
than lugged brazing.

--
[email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/

do not sail on uphill water
- Bill Lee

 

[Simon Brooke]

[email protected] (Carl Fogel) writes:

> Have these modern steel alloys made brazing pointless, or is the welding a matter of cost and
> convenience? Is there a practical difference in the strength of the joints? Can non-steel frame
> parts be brazed to each other or to steel pieces?

Dissimilar metals often can be brazed or soldered; they generally can't be welded. In welding, the
metal of the two workpieces melts and flows together; so to weld two dissimilar metals they must
have very similar melting temperatures and must also form a strong alloy. I suppose it's possible
and someone's going to come along in a minute and give us an example, but I don't myself know of
one. Welded joins should in principle be a little stronger than brazed or welded, but I doubt it
makes a real difference in practice.

For bicycle purposes both brazing and welding are pretty skilled tasks (I can do both to a rough
degree but wouldn't rate myself capable of making a bicycle frame).

--
[email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/

do not sail on uphill water
- Bill Lee

 

[Jim Beam]

> Can anyone say _why_ welding is preferred for mass produced frames? I would have thought (perhaps
> naively) that with tubes as thin walled as bicycle tubes, welding would call for even more skill
> than lugged brazing.

tig is cheaper - fewer stages in manufacture and fewer parts. tig is more versatile - wider range of
angles without retooling. tig /can/ be lighter.

tubes made for tig welding are often thicker at the ends than tubes for brazing. this allows a good
strong joint. it also allows for a little "variability" in the skill of the welder.

human tig welding skill, as you might imagine, is highly variable. but because it's a highly
localized melt and there is no flux, it's easy enough to stop & start yet still achieve a
sufficiently strong join of acceptable cosmetic finish. you could probably do it with just a
little practice.

also, don't forget that a lot of mass-produced welds are done by some form of automated or
semi-automated process. this is particularly true of ti. just compare finish quality of cheapo steel
manual tig welds to the often automated titanium tig welds!

 

[Jim Beam]

> Dissimilar metals often can be brazed or soldered; they generally can't be welded.

not necessarily so. electron beam and laser welding techniques are often deployed in welding
difficult and dissimilar materials. this does not mean that /all/ materials can be joined in this
way, but it provides opportunities that were not previously possible.

cost, of course, is a /significant/ factor determining deployment.

 

[Matt O'Toole]

"Simon Brooke" <[email protected]> wrote in message
news:[email protected]...

> Can anyone say _why_ welding is preferred for mass produced frames? I would have thought (perhaps
> naively) that with tubes as thin walled as bicycle tubes, welding would call for even more skill
> than lugged brazing.

Robots are highly skilled!

Lightweight bicycle tubes are generally thin in the middle, but much thicker in the ends where
they're welded. (ie, butted)

Did you read the Keith Bontrager article posted to this thread? That should answer any other
questions you might have.

Matt O.

 

[Simon Brooke]

"Matt O'Toole" <[email protected]> writes:

> "Simon Brooke" <[email protected]> wrote in message
> news:[email protected]...
>
> > Can anyone say _why_ welding is preferred for mass produced frames? I would have thought
> > (perhaps naively) that with tubes as thin walled as bicycle tubes, welding would call for even
> > more skill than lugged brazing.
>
> Did you read the Keith Bontrager article posted to this thread? That should answer any other
> questions you might have.

I hadn't, but I now have - thanks.

--
[email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/

do not sail on uphill water
- Bill Lee

 

[Jim Beam]

> Did you read the Keith Bontrager article posted to this thread? That should answer any other
> questions you might have.

with all due respect to keith, his metallurgy was a little bit askew. shot peening does /not/ reduce
residal stress for example - i'm sure he meant to say it reduces fatigue. similarly comments about
phase changes and annealing - should not occur to any significant degree during normal brazing - if
it /is/ happening, it's being done wrong. finally, his tig welding h.a.z. comments do not
acknowledge the role of air-hardening tube in this arena - it's specifically designed to negate the
effects he describes. great comment otherwise.

jb

 

[Rod Jenkins]

> Dear Rod,
>
> For the sake of the fascinated layman, could you be coaxed into expanding on the subject?
>
> Have these modern steel alloys made brazing pointless, or is the welding a matter of cost and
> convenience? Is there a practical difference in the strength of the joints? Can non-steel frame
> parts be brazed to each other or to steel pieces?
>
> Judging by your post, even random thoughts from you on the matter will be a pleasure to read.
>
> Hopefully,
>
> Carl Fogel

Kind words Carl. Any expertise I have is largely derived from model engineering not from frame
making so I am unable to comment on the relative merits of frame construction. However, in my
limited experience, if steel frames break, it is not because the silver soldered lug has become
"un-glued". My guess is that changes in metal bike frame materials are largely down to production
engineering (cost) considerations rather than the relative merits of joining techniques, which are
all adequate for the purpose.

Rod