[Closed] Ti vs Alloy

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...