Titanium pedal in Aluminum crank?

Claes said:

Hi, new pedals, the old time [censored] is hitting the bin as soon as a I
come home now.
Anyhow, these have a titanium spindle, and I have aluminum cranks.
Will there be any issues with mounting it? I have read of "welding"
issues and stuff. do I need some ti prep or something?

The old ones will be steel, probably, same issues. Always grease the
threads.

consider using jointing compound - stops the 'dissimilar metals' effect

"Bleve" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Claes said:

Hi, new pedals, the old time [censored] is hitting the bin as soon as a I
come home now.
Anyhow, these have a titanium spindle, and I have aluminum cranks.
Will there be any issues with mounting it? I have read of "welding"
issues and stuff. do I need some ti prep or something?

The old ones will be steel, probably, same issues. Always grease the
threads.

jim said:

consider using jointing compound - stops the 'dissimilar metals' effect

Consider not buying titanium axles - stops the 'broken axle causing gash
in ankle' effect

Quoted message said:

"Bleve" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Claes said:

Hi, new pedals, the old time [censored] is hitting the bin as soon as a I
come home now.
Anyhow, these have a titanium spindle, and I have aluminum cranks.
Will there be any issues with mounting it? I have read of "welding"
issues and stuff. do I need some ti prep or something?

The old ones will be steel, probably, same issues. Always grease the
threads.

Claes <[email hidden]> wrote in
news:[email hidden]:

Quoted message said:

Hi, new pedals, the old time [censored] is hitting the bin as
soon as a I come home now.
Anyhow, these have a titanium spindle, and I have aluminum
cranks. Will there be any issues with mounting it? I have
read of "welding" issues and stuff. do I need some ti prep
or something?

Cheers.

Brass or steel will set an electrolysis effect but titanium
won't. They are covalently similar metals (check the
periodic table some time).

Cheers

BrettM

'copaslip'
Steve
IDEAL Cycles

John Stevenson said:

jim wrote:

Consider not buying titanium axles - stops the 'broken axle causing gash
in ankle' effect

Ouch! Which brand? I see Crank Bro's spec a max weight with their Ti's.

BrettM said:

Claes <[email hidden]> wrote in
news:[email hidden]:

Quoted message said:

Hi, new pedals, the old time [censored] is hitting the bin as
soon as a I come home now.
Anyhow, these have a titanium spindle, and I have aluminum
cranks. Will there be any issues with mounting it? I have
read of "welding" issues and stuff. do I need some ti prep
or something?

Cheers.

Brass or steel will set an electrolysis effect but titanium
won't. They are covalently similar metals (check the
periodic table some time).

similar != "the same"

On 21/11/05 at 16:26:13 Claes somehow managed to type:

Quoted message said:

Hi, new pedals, the old time [censored] is hitting the bin as soon as a I
come home now.
Anyhow, these have a titanium spindle, and I have aluminum cranks.
Will there be any issues with mounting it? I have read of "welding"
issues and stuff. do I need some ti prep or something?

Cheers.

Dissimilar metals equals corrosion which is not good. Just make sure
that everything is nice and clean and shiny and give it all a liberal
coating of Copaslip. Problem solved...:-)

--
Humbug
BE A LOOF! (There has been a recent population explosion of lerts.)

On 21/11/05 at 22:51:28 BrettM somehow managed to type:

<snip>

Quoted message said:

Brass or steel will set an electrolysis effect but titanium
won't.

I doubt that there's an aircraft operator who'll believe you.

--
Humbug
BE A LOOF! (There has been a recent population explosion of lerts.)

"Bleve" wrote in message ...

Quoted message said:

BrettM said:

Quoted message said:

Brass or steel will set an electrolysis effect but titanium
won't. They are covalently similar metals (check the
periodic table some time).

similar != "the same"

Valency has very little to do with it. What you need to look at is the electrode (aka galvanic) potential. Titanium and Aluminium
are (as far as metals are concerned at opposite ends of the scale, which mean electrolysis will be more of a concern.

Parbs

"Parbs" <[email hidden]> wrote in
news:[email hidden]:

Quoted message said:

"Bleve" wrote in message ...

Quoted message said:

BrettM said:

>

Brass or steel will set an electrolysis effect but
titanium won't. They are covalently similar metals
(check the periodic table some time).

similar != "the same"

Valency has very little to do with it. What you need to
look at is the electrode (aka galvanic) potential.
Titanium and Aluminium are (as far as metals are concerned
at opposite ends of the scale, which mean electrolysis will
be more of a concern.

Parbs

True, and if you couple pure titanium and pure aluminium in a
saline environment then the aluminium will corrode rapidly.
But add a little nickel to the aluminium and the couple will
be almost inert. Most aluminium alloys used in bikes include
nickel. Ti-Al or Ti-Al-Ni/Nb alloys are commonly used for
surgical procedures (pins/plates etc) because they are stable
within a saline environment.

There should also be little concern in blending stainless
steel with titanium but it will depend on the admixtures.

As for aircraft there are a whole host of things going on for
Ti that create corrosion issues but many rotor hubs include
stainless, aluminium and titanium parts as do most turbines.
You have to monitor electrolysis but then you also monitor
fatigue etc. Just another thing to worry about if you fly I
suppose, that's why I prefer to take a parachute ;-)

(Try explaining to a pilot that you only consider aircraft as
either targets or platforms to leap from)

Cheers

BrettM

On 22/11/05 at 22:42:21 BrettM somehow managed to type:
<snip>

Quoted message said:

As for aircraft there are a whole host of things going on for
Ti that create corrosion issues but many rotor hubs include

I wasn't thinking of engine bits, I was thinking of Al alloy control
quadrants with Ti bolts that have to be removed and inspected at
regular intervals. I wouldn't have a clue about HOW they seize but they
do, and <rant> because it's aircraft related everything costs about 10
times what it would if it was a bloody car. </rant>

<snip>

Quoted message said:

(Try explaining to a pilot that you only consider aircraft as
either targets or platforms to leap from)

As an on 'n off jumper and pilot (fixed singles and balloons) for the
last 30 years.....

--
Humbug
BE A LOOF! (There has been a recent population explosion of lerts.)

On 22/11/05 at 22:42:21 BrettM somehow managed to type:
<snip>

Quoted message said:

As for aircraft there are a whole host of things going on for
Ti that create corrosion issues but many rotor hubs include

I wasn't thinking of engine bits, I was thinking of Al alloy control
quadrants with Ti bolts that have to be removed and inspected at
regular intervals. I wouldn't have a clue about HOW they seize but they
do, and <rant> because it's aircraft related everything costs about 10
times what it would if it was a bloody car. </rant>

<snip>

Quoted message said:

(Try explaining to a pilot that you only consider aircraft as
either targets or platforms to leap from)

As an on 'n off jumper and pilot (fixed singles and balloons) for the
last 30 years.....

--
Humbug
BE A LOOF! (There has been a recent population explosion of lerts.)

"Humbug" <[email hidden]> wrote in
news:[email hidden]:

Quoted message said:

On 22/11/05 at 22:42:21 BrettM somehow managed to type:
<snip>

Quoted message said:

As for aircraft there are a whole host of things going on
for Ti that create corrosion issues but many rotor hubs
include

I wasn't thinking of engine bits, I was thinking of Al
alloy control quadrants with Ti bolts that have to be
removed and inspected at regular intervals. I wouldn't have
a clue about HOW they seize but they do, and <rant> because
it's aircraft related everything costs about 10 times what
it would if it was a bloody car. </rant>

<snip>

Quoted message said:

(Try explaining to a pilot that you only consider aircraft
as either targets or platforms to leap from)

As an on 'n off jumper and pilot (fixed singles and
balloons) for the last 30 years.....

IIRC that's related to a combination of stress corrosion and
electrolysis with the second being a minor concern. Both
materials oxidize in the same way and when they bear against
each other they tend to strip the oxide away from each other
leading to erosion over time.

Agree totally with the cost bit - I stopped after PPL and
haven't maintained currency because I couldn't afford it:-(

Cheers

BrettM

JayWoo said:

John Stevenson said:

jim wrote:

Consider not buying titanium axles - stops the 'broken axle causing
gash
in ankle' effect

Ouch! Which brand?

All of them. Replacing steel with titanium without changing the design
to take account of the material's different properties is a certain way
to increase the risk of failure.

quote='John Stevenson'JayWoo said:

John Stevenson said:

jim wrote:

Consider not buying titanium axles - stops the 'broken axle causing
gash
in ankle' effect

Ouch! Which brand?

All of them. Replacing steel with titanium without changing the design
to take account of the material's different properties is a certain way
to increase the risk of failure.[/QUOTE]
Wow! So you've worked on the R&D Teams for all Companies making Ti pedals?

Sorry to have a spray BRettM but most of your answers so far have been
nothing short of woeful.

It doesn't matter what you do, if you have two dissimilar metals in
electrical contact, one of them will corrode. HUmbug is right - as long as
you eliminate that coupling, you are OK to go. Sure, the degree of corrosion
will change depending on the electrolytic potentials of the two metals. Bang
some grease on there and make sure there is no place for the water to pool.
You should be ok. Note: some greases contain lithium, which will make your
grease conductive --> bad.

Quoted message said:

True, and if you couple pure titanium and pure aluminium in a
saline environment then the aluminium will corrode rapidly.
But add a little nickel to the aluminium and the couple will
be almost inert. most aluminium alloys used in bikes include nickel.

No they do not. The Al-Mg-Si (6xxx series) do not contain Nickel (6061 is
1.0 Mg, 0.7 Si, 0.3 Cu, trace Ti), nor do the Al-Zn (7xxx) series (7005 is
4.6 Zn, 1.4 Mg, 0.5 Mn, 0.1 Cr,0.1 Zr, 0.03 Ti) which are the most common of
aluminium alloys used in frames. In fact, Nickel has a maximum solid
solubility of 0.04 wt% in Al. You are correct in saying that Nickel improves
corrosion resistance, but it's influence would be minor. The addition of
titanium is more common, but it is added for grain refinement (strength
increases) rather than for improved corrosion resistance. Chromium is often
added to counteract the negative effects that copper has on corrosion
resistance.

Quoted message said:

Ti-Al or Ti-Al-Ni/Nb alloys are commonly used for
surgical procedures (pins/plates etc) because they are stable
within a saline environment.

I think you will find that Ti-Al-V are more common. Yes they are more stable
but they also do not suffer from stress corrosion cracking (c.f. 3xx series
stainless steels). The lower Young's modulus, E (~120GPa), of titanium
compared with steel (207 GPa) also allows for improved tissue integration
(e.g. bone growing into the surface of the implant).

Quoted message said:

There should also be little concern in blending stainless
steel with titanium but it will depend on the admixtures.

"blending stainless with titanium" . See point above about dissimilar
metals.
"admixtures". ever heard of alloying composition?

The biggest issue with titanium is fatigue strength. As I have mentioned on
here before, localised oxidation due to fretting reduces the fatigue life of
titanium massively. Keep those titanium bits well greased.

Anyway, that's my rant

Jimbo

Jimbo Jones said:

Sorry to have a spray BRettM but most of your answers so far have been
nothing short of woeful.

It doesn't matter what you do, if you have two dissimilar metals in
electrical contact, one of them will corrode. HUmbug is right - as long as
you eliminate that coupling, you are OK to go. Sure, the degree of corrosion
will change depending on the electrolytic potentials of the two metals. Bang
some grease on there and make sure there is no place for the water to pool.
You should be ok. Note: some greases contain lithium, which will make your
grease conductive --> bad.

Quoted message said:

True, and if you couple pure titanium and pure aluminium in a
saline environment then the aluminium will corrode rapidly.
But add a little nickel to the aluminium and the couple will
be almost inert. most aluminium alloys used in bikes include nickel.

No they do not. The Al-Mg-Si (6xxx series) do not contain Nickel (6061 is
1.0 Mg, 0.7 Si, 0.3 Cu, trace Ti), nor do the Al-Zn (7xxx) series (7005 is
4.6 Zn, 1.4 Mg, 0.5 Mn, 0.1 Cr,0.1 Zr, 0.03 Ti) which are the most common of
aluminium alloys used in frames. In fact, Nickel has a maximum solid
solubility of 0.04 wt% in Al. You are correct in saying that Nickel improves
corrosion resistance, but it's influence would be minor. The addition of
titanium is more common, but it is added for grain refinement (strength
increases) rather than for improved corrosion resistance. Chromium is often
added to counteract the negative effects that copper has on corrosion
resistance.

Quoted message said:

Ti-Al or Ti-Al-Ni/Nb alloys are commonly used for
surgical procedures (pins/plates etc) because they are stable
within a saline environment.

I think you will find that Ti-Al-V are more common. Yes they are more stable
but they also do not suffer from stress corrosion cracking (c.f. 3xx series
stainless steels). The lower Young's modulus, E (~120GPa), of titanium
compared with steel (207 GPa) also allows for improved tissue integration
(e.g. bone growing into the surface of the implant).

Quoted message said:

There should also be little concern in blending stainless
steel with titanium but it will depend on the admixtures.

"blending stainless with titanium" . See point above about dissimilar
metals.
"admixtures". ever heard of alloying composition?

The biggest issue with titanium is fatigue strength. As I have mentioned on
here before, localised oxidation due to fretting reduces the fatigue life of
titanium massively. Keep those titanium bits well greased.

Anyway, that's my rant

Jimbo

Don't forget that carbon fibres are good conductors of electricty (I've
measured them), so all your bike bits are connected together even on
"plastic" bikes.

Marty

Quoted message said:

Don't forget that carbon fibres are good conductors of electricty (I've
measured them), so all your bike bits are connected together even on
"plastic" bikes.

Marty

I know you're not being all that serious but you've got me curious now. How
conductive *are* carbon fibres? I seem to recall that carbon "nanotubes" are
fantastic conductors along their length but equally fantastic insulators
otherwise. I'm guessing that the resin matrix for CF is a reasonable
insulator, so would CF only conduct where it's been cut, fretted or
otherwise had the fibres exposed? And a thought that just popped unbidden
into my head and which is almost entirely unrelated, how about some kind of
standardised connectors and wires embedded into CF frames during layup for
cadence and wheelspeed sensors (use the rear wheel to avoid issues with the
fact that fork have to be able to turn) to clean up wiring? It's internal
cable routing for the 21st century! 🙂