Copper grease on freehub when mounting sprocket?

Question

Do you put copper grease (or something else) on a freehub directly before sliding the rear sprocket on? I put a light coating on by habit when fitting just because I don't like the idea of bare metal-on-metal, and copper grease seemed right by instinct. But that instinct is from bicycles whose engines prefer refined hydrocarbons to pie'n'mash. There was nothing or a very light oil when I took the old sprocket off, but it didn't come off that easily either.

Presumably you should also put something on the threads of the lockring; I actually forgot that, but I'm minded to put a little bit of copper grease in there too next time I take it off.

The sprocket (and the chain, and one spoke in the rear wheel...) are all new. (There's a chain stretch tool now hanging up next to the bike, so hopefully the next chain change won't involve replacing a spoke.)

This question recommends any old grease, but copper grease isn't a lubricant, so this strikes me as a separate question.

Answer 1

Antiseize/copper grease is theoretically better, but plain old grease will work just fine. There’s no relative motion here, so lubricity is not a factor. All we are looking for is adding corrosion resistance to avoid sprockets being fused to the freehub body or the lockring getting stuck.

I personally use grease on the freehub body and antiseize on the lockring, but exclusively using either is equally good. I don’t want to have the mess that is an antiseize-covered freehub body.

Answer 2

Greasing the freehub body splines is good when it's prone to creaking for whatever reason, which is largely a problem specific to aluminum shallow-spline (as opposed to the deep splined FH-7800 and WH-7800) freehubs and their issues with getting notched up. The lubrication can mitigate the noise, but not the damage.

A coat of grease or antiseize is also reasonable in corrosion-prone environments, like salted roads or ocean air.

Antiseize is the messiest thing you could choose for either purpose, but will probably outperform grease were you to test. (It usually does in testing for basically everything but reducing friction and wear in bearings.)

Other than that, greasing freehub splines mostly is messy with little or no benefit. Steel freehubs can get some rust sometimes, but it's of no consequence outside of the above circumstances.

Lockring threads should always be lightly lubricated, but you also need to keep grit from sticking in that area. I usually do a small dot of grease. On bikes that I know get maintained with any regularity I do a few drops of oil flowed through the threads, rationale being that's well sufficient to prevent any actual problems and is also the neatest. If it's a titanium freehub body, use a small amount of antiseize applied very carefully, because you want to keep it out of the bearings.

Answer 3

I think you are referring to copper antiseize, which is usually recommended to prevent galvanic corrosion with titanium bike parts. Generally, I would antiseize any interface where one of the parts is titanium.

Almost all freehub bodies are aluminum or steel. They're interfacing with aluminum cog spiders and steel cogs. (NB: Shimano and Campagnolo's top end cassettes have titanium largest cogs, but all these are mounted to aluminum spiders). Thus, you don't need copper antiseize here. I believe that antiseize is really grease with copper particles added, and if true then there's no harm in using it apart from it being unnecessary.

However, come to think of it, some titanium freehub bodies exist. White Industries and some older Shimano Dura Ace and XTR FH bodies are titanium. I have had a White Industries rear hub for a couple of years and I haven't noticed any problems with seizing. In theory, antiseize would not be a waste here, however.

Answer 4

You're right - copper grease/assembly compound is not a lubricant. But threads generally don't move once assembled+torqued, so don't need lubricant anyway. Having something to stop them seizing together is a different purpose than lube, though grease can do both tasks.

Personally I use copper clay on all threads, grease in bearings, and light oils on pivots.

The only people who would use less would be pro racers who would use oil, or nothing, for ultimate lightness in races.