[Closed] Ti vs Alloy

When did you notice that there might be a problem?

But you lose cos you spent mega bucks on a ti frame!!

Took the bike down off the wall yesterday morning to go to work and the cranks wouldn't spin. A wee bit of heaving later, there was a loud *crack* and then they were free. However, I had a wee look and noticed that the drive side BB was spinning with the cranks....

Oh and £360 ain't megabucks

/pedant mode/ The Ti used in bike frames is an alloy as it is a mixture of other metals. Did you mean "titanium alloy vs Aluminium Alloy"
/pedant mode/

I used to have mm deep grooves worn into a Litespeed titanium frame frame caused by rubbing PLASTIC-coated cables (with no corresponding damage to the cable(?) , and a deep groove caused by the RUBBER tyre rubbing under power on the inside rear stay.
Materials are funny things.

OP - looks morelike "Ti vs. crappy installation"

*runs*

west kipper - the plastic grips dirt that then rub into the metal.

And the moral of this story? Use Ti-Prep/Molly Grease/Copper Grease when installing anything on a ti frame.

[i](cue lots of other alternative morals to this story fuelled by the inevitable and endless 'ti is overpriced rubbish' and 'my material is better than your material' gangs that seem to inhabit STW!)[/i]

How would that have helped? Do you know the cause of the failure?

Yes, I realised that cynic-al, though I'm still surprised that the dirt was tougher than Ti (maybe we should make frames from dirt?)
BTW, I'm glad you dropped that first sentence with druidh yourself- I was thinkin' it 🙂

Given the force required, the loud crack and the remnants of material left on the bb threads, this looks like a clear case of bi-metallic corrosion. Ti and alloy are famous bed-fellows for this. Over time the components of the 2 materials fuse together at a molecular level and almost become 1 component. This is the classic cause of alloy seatposts becoming stuck in metal frames (and the reason why Seven put a unidirectional carbon fibre sleeve in their ti frames, so there is no metal-to-metal contact).

The best way to stop it is to introduce some sort of barrier element that counteracts the process. Moly grease is probably the best of all as it works on a molecular level, is completely inert and resistant to heat, moisture and force. I have used it for years on all threaded metal-to-metal contact points, and wherever bi-metalic corrosion could occur and have never had a problem. Even after months and years of all weathers riding, components come apart easily, and just need a wipe of the threads to come up as good as new.

It looks like the threads from the BB have come off in the frame. Is that right? Can the threads (in the frame) be chased clear?

Dirt = broken up rocks. Ti ain't that hard.

druidh needs to be kept in line 😡 otherwise he gets all C2W nazi 😀

Copper grease [i]was[/i] used during installation. Mind you, that was 2 years - and a good few miles - ago. The bearing has actually seized solid and the threads in the BB shell are still perfect 🙂

solarider, you're only coming up with the defence because of your vested interest- we all have seen how you own 78.3% of the world titanium frames. 🙂

Copper grease won't last 2 years, as you can see from the picture. There is no trace of it left. Next time, re-apply more frequently or go for Moly Grease. Like any of these:

http://shop.ebay.co.uk/items/__molybdenum+grease_W0QQ_dmdZ2?rvr_id=&crlp=3020810357_229447_229457&UA=WXI6&GUID=b928754e1270a0e201d459d4ffd61c64&agid=1020327707&MT_ID=10&keyword=molybdenum+grease&ff4=229447_229457

Stays put for years.

Don't know what you mean (and it's 78.4% by the way).

I should really edit the above post before anyone comes along and starts arguing that HTII BBs can't possibly last 2 years anyway.

solarider - thanks for the advice. I'll try to remember. The NDS BB came out a treat btw.

My apologies druidh - it was crappy maintenance 😀

Maintenance?

I'll have to go google that....

I wouldn't bother at the rate you replace your bikes 😛

I didn't really see myself as one of the serial bike changers...

ChiTi - 2 years and no intention of changing
Cayo - 2 years. Might look for an end-of-year bargain later this year *cough*
Blur - Last summer, but had the Meta for 3 years before that?
Sutra - 4 years and just recently replaced.

How many new bikes have you had these last 12 months Al?

Thing is, I wouldn't have had any BB in a Ti frame for so long without occasionally doing a strip down, usually Ti bikes start creaking sooner than other metals, especially if they're used in the rain-do you live anywhere it rains druidh?. 🙂
Its one of the massive benefits of HT2, the job takes minutes, so its not even much hassle.

Heh, I knew you'd bite. You've bought 2 in the last 12 months?

I'm on 3 I think, though I don't count the Heckler as I had one before.

Heckler 2005 - present (bar Nomad for 1 year)
Shand 2006 - present
Ritchey 2004 - 2009 (Principia)
Hewitt 2003 - 2009 (Salsa)

Looking at that I think you've changed bikes mpre than me in the last few years 😛

Why do people use Copa Slip / copper grease on bikes?

Aye, its horrible stuff that makes the bike look like its weeping rust from the threads.

cynic-al - Member
Heh, I knew you'd bite. You've bought 2 in the last 12 months?

I'm on 3 I think, though I don't count the Heckler as I had one before.

Heckler 2005 - present [b](bar Nomad for 1 year)[/b]
Shand 2006 - present
Ritchey 2004 - 2009 (Principia)
Hewitt 2003 - 2009 (Salsa)

Looking at that I think you've changed bikes mpre than me in the last few years

Probably right - it's just that [i]some[/i] folk seem to get turn over their bikes a lot more often than me.....

Dirt is ground up minerals, and minerals are very hard indeed. No good for frames of course since they are brittle.

That's why dirty chains wear very very fast, because the grit is so hard.

Why do people use Copa Slip / copper grease on bikes?

See my post above. Prevents this kind of bi-metallic corrosion. The copper acts as a kind of inert barrier between 2 metals that would otherwise fuse. It's no a lubricant, so can;t be used on moving parts. It's just for static parts. Moly grease is better though.

I am a big user of coppaslip. I have heard it said on there that it causes catalytic corrosion but I use it all the time on dissimilar metals. Anyone got an explanation for this tendency to cause corrosion?

Bolts that might work loose or are safety critical - loctite.
Nuts and bolts of the same material - moly grease
Bolts bolted into disimilar metals (ie Steel caliper bolts) - coppaslip

I never have issues with stuff seizing - motorcycles or bicycles. Mind you I was appalled that my new bike had been assembled with a lot of dry threads. Some corroded after a few months - I stripped the entire bike to reassemble properly

Copper grease is for high temperature conditions.
Copper grease, does it not cause galvanic corrision?
The picture in the OP looks a lot like galling.

[url= http://www.finishlineusa.com/products/ti-prep.htm ]Previously called Ti Prep[/url]

"Copper grease won't last 2 years"

Rather a sweeping statement. Where is it going to go then? Can't get washed out trapped between threads, if applied correctly it's still visible upon dismantling whatever the time period.

Corrosion usually takes place where stuff stays wet (eg being sprayed by road salt). I've not researched, but my guess is coppaslip is better than nothing in this sense but it's non-conductive properties will get ****ed up the arse by grease.

Coleman - Member
> "Copper grease won't last 2 years"

Rather a sweeping statement. Where is it going to go then? Can't get washed out trapped between threads, if applied correctly it's still visible upon dismantling whatever the time period.

I should point out that I did actually clean the BB shell before taking the photo - just to make it easier to see the damage.

Finish Line Anti Seize is that not Bostik Never Seize, which is not copper based.

Campagnolo recommend Loctite 222 Threadseal for BB threads.

What part of a bike gets up to the temperatures that needs copa slip?
http://www.molyslip.co.uk/anti_sieze_compounds/

From the molyslip site..

A single application of Copaslip (often misspelled as copperslip or coppaslip) or Alumslip will stop metal fusion for [b]many[/b] years.

Many=>2??

Is copper a good conductor?
http://www.stainless-steel-world.net/titanium/ShowPage.aspx?pageID=173

Campagnolo Loctite 222 thread lock/seal

Galling
http://www.finishing.com/Library/titanium.html

The poor thermal conductivity of titanium also cortributes to the galling problem.

Macavity - Member

Copper grease is for high temperature conditions.

that would make sense - exhaust studs on motorbikes and brake mountings is two common places - ordinary grease would boil / burn away but the copper would remain.

Copper grease, does it not cause galvanic corrision?

So I have heard said on here but I would like to hear a bit more explanation as it doesn't IME

"Copper grease won't last 2 years"

Rather a sweeping statement. Where is it going to go then? Can't get washed out trapped between threads, if applied correctly it's still visible upon dismantling whatever the time period.

Are you kidding? There are 2 places that water washes into your frame. Firstly down the seat tube (from the back wheel), and secondly through the bb (from the front wheel). Regardless of wherever and however it enters your frame, the bb is the lowest point in your frame and where all water eventually collects. It absolutely will make its way between threads and wash out copper slip. In extreme cases (and I am not accusing the OP here), the bb can literally be submerged in water inside the frame.

That's why Phil Wood (RIP) bbs, which are reknowned for their longevity, use submarine bearings. It's also why so many frames have drain holes under the bb shell, to release any water which would otherwise wash out grease around the threads and the bearings from the inside out.

Have you not ever removed a bb and released at least a little water, or found the shell covered in mud (the residue from dirty water having found its way down there)?

It's simple physics. In descending order of density you have solids, liquids and then gasses. Since a liquid (in this case water) is less dense than a solid (in this case copper slip), it will find its way in there.

Moly resists water and friction better than copper grease. In either case, a regular re-application would be advisable, but what constitutes 'regular' depends on how regularly the bike gets ridden in the wet.

Solarider - thats not my experience - coppaslip remains in there for a long time - it is particles of solid after all and there is no force behind the water to drive it out.

Time, not pressure is the key variable here. It's not a matter of pressure, it's a matter of how long the water sits down there, gradually seeping in. If 'solid to solid' were such a water-tight fit, why would you have rubber washers on plumbing/ Why would your threaded shower fitting leak if it didn't have a rubber washer? Why would one of the ways to remove a stuck seatpost be to turn the bike upside down and let some penetrating oil do its thing overnight? No matter how tight the interface, and how much pressure is applied, it is a physical certainty that a liquid will penetrate in between 2 solids. If the gap if really small, perhaps only a gas will do, but even the best engineered bbs and frames aren't built to those kind of tolerances.

Don't get me wrong, copper grease is good, but don't be fooled into thinking it (or any grease, even moly) is going to stay there for life.

We do seem to have lost the point of the original thread, but if a few people remove their bbs and regrease them (with any grease quite frankly except butter) this weekend, it will have stopped an awful lot of creaking and the potential for this to happen to someone else.

Cheers solarider

And in addition to what solarider says, you should (as I do) remove your seatpost and invert the frame after it's been very wet - to let any water escape.

Or have a hole in the BB shell as I do 🙂

Is moly grease that super thick gloopy stuff? Got a Ti frame on the way & want to build it up correctly.

With titnium (sic) alloys they tend to be corrosion resistant, its really all about preventing galling which the copaslip is good at doing. Even when coupled with aluminium alloys it will not accelerate the corrosion of the titanium over its normal uncoupled rate. But it may well make the aluminium ally corrode more....
With steel/aluminium joints there there is a galvanic corrosion problem both ways. Any decent grease will be fine for BB apps where its steel/Al alloys.

edit pedalhead use copaslip or any copper grease halfords do a massive pot for life for about 7 quid (although I bet moly would be fine too).

TandemJeremy - Member
Or have a hole in the BB shell as I do

I put a blob of grease on the inside of the drain hole in the BB. Stops muck getting in, but if water builds up inside, it pushes the blob out and then drains.

Not what you need first thing in the morning Druidh!

At least your frame is ok.

just checked in my "hong kong book of kung foo" and moly grease is great, poss better at preventing galling than copper grease, also graphites good too.

Out of curiosity then... if it had been an aluminium frame, what would the result have been.

Or a steel one?

Remember, the bearing isn't turning at all.

I guess if it was caused by the bb cup turning in the shell then steel vs alu - steel likely to win, alu vs alu dunno.. probably both ****ed.

Personally I wouldn't want to find out the effects of turning an alloy cup in any flavour frame, I think it was lucky to have not damaged your threads.

Even though titanium is corrosion resistant, titanium will readily combine with oxygen and nitrogen in certain conditions.

When screwing an aluminium BB cup into a titanium BB shell if the threads are good then grease of any kind will be OK. If the threads are slightly distorted, damaged, out of round etc then there is the possibility of galling.
Simply, galling is where metals start to behave more like velcro than solid metal.
Any aluminium BB cup will have some Al oxide (a hard ceramic, abrasive grinding material) on the surface of the threads and this will scrape the surface of the Ti BB threads. The freshly exposed titanium surface that has been scraped, will now want to react with some thing. That some thing will be what ever it is touching.
The conservation of energy means that the work done in turning even a very slightly tight cup into a BB shell will create heat. This all leads to galling. Titanium is a poor conductor of heat (for a metal) so localised hotspots occur.
Think of the BB cup as a VERY blunt cutting tool when reading the bit below.

http://www.titanium.com/titanium/tech_manual/tech2.cfm
"Working with Titanium: Titanium is highly reactive and will react with its environment at relatively low temperatures. When it is heated in air, a self-protective, titanium-oxide film, which is very adherent, will form on its exposed surfaces. In many corrosive environments, the film becomes a barrier and, in the absence of abrasion will decrease the corrosion rate."
"Titanium has a tendency to gall, and its chips can weld to the cutting edges of the tool. This is particularly so once tool wear begins. Sharp tools should be employed at all times and should be replaced before they dull. The feed should not be stopped while the tool and work piece are in moving contact."
"Titanium has been classified as difficult to machine due to its physical properties. Heat caused by the cutting action does not dissipate quickly because titanium is a poor heat conductor. Titanium has a strong alloying tendency or chemical reactivity with material in the cutting tools which cause galling welding, smearing and rapid destruction of the cutting tool. "

Still thinking of an aluminium BB cup as a very blunt tap?
Good.

By the way, why do people use copper grease on bikes?

Molybdenum disulfide comes in various forms: grease, oils and dry (spray on).
Rocol amongst others do Dry Moly lube, as an aerosol that dries almost like paint.

But for threaded parts Loctite do a range of thread lock and thread seal.

maybe we should make frames from dirt?

It's simple physics. In descending order of density you have solids, liquids and then gasses.

Macavity - Member

By the way, why do people use copper grease on bikes?

I have always used it for its anti seize properties. Used between two dissimilar metal where the thread will be undisturbed for a long time but I don't want threadlock

You sound like you know what you are talking about and I have herad criticism of copaslip being used on bikes but never been given any information that makes sense as to why not - and I have found coppaslip to be better than ordinary grease be so any information you have would sate my curiosity on this

I'm with TJ on the copaslip use, I use it on lots of parts (BB's, headset cup installation etc...) and never have any seizing. The only criticism I've heard is that it's very carcinogenic and you should use gloves etc...

I have 1 bike (s works alu hardtail) with a drain hole and a Genesis Alpitude without a drain hole. The genesis is often full of water at the BB and the s-works is always dry! I may drill a hole in the genesis. Think in practical terms it makes sense. I find with copaslip that after long installation all that's left is dry copper powder but the things still release...that has to be good no?

Question for Macavity - given that the headset was installed at the same time as the BB, should I remove it and re-apply some copperslip?

Copper grease is not recommended on ti frames.Its something to do with the copper content reacting with the ti and Aluminium.

2 words.

MOLY PASTE!

I don't have shares in any companies manufacturing the stuff, it's just so much better than anything else at its job. Can be used on any metal, lasts a long time and prevents any of the problems highlighted in this thread.

nicolaisam - Member
Copper grease is not recommended on ti frames.Its something to do with the copper content reacting with the ti and Aluminium.

Rollocks. Copper Grease is otherwise known as Ti Prep - and for a very good reason.. Try reading the rest of the thread.

druidh - Member
Question for Macavity - given that the headset was installed at the same time as the BB, should I remove it and re-apply some copperslip?

solarider-It's simple physics. In descending order of density you have solids, liquids and then gasses.

<pedant mode> you mean like how solid steel will float in liquid mercury, or iceberg float in the ocean </pedant mode>

Could lithium grease be used in such cases as Druidh's?

EDIT : One of my clients is an aircraft fastener supplier, they say never use copper grease on aluminium, because of dissimilar metal corrosion. The use duralac and never seez. Used by lotus, boeing, bombardier, airbus and the rest.

"Copper grease won't last 2 years"

id argue that.. as someone who rides on beaches and through a hell of alot of salt water often ive not had anything sieze coated in coppergrease in 2 1/2 years on a bike thats now done 2000 miles...
and that is everything from gear and cable disc brake inner cables to headset cups,BB cups (phil wood) and every threaded nut and bolt...
next time your down at a harbour have a look at the cranes on fishing boats and see whats oozing out the grease points...yep copper grease 😮
TOP TIP; get some graphite grease for sealed wheel bearings... wurth sell it here in the UK (motor trade suppliers),it was originaly designed for alaskan mining machinery which as you can imagine has quite a tough time...the idea is if it does wash out the graphite helps prevent the dry bearing heating and seizing..not replaced any bearings since i started repacking them when new with this stuff 2 years ago...

though i do think that the cheaper brands of coppergrease like coma that you see in halfords etc is bound to be lower quality- just like cheapo car oil...

I think what's normal for the aircraft industry is a bit of overkill for the bike industry, I've been using copper grease for years without problems... But I just wanted to let you know what the aircraft boys told me...