Shimano freehub - what lube?

[Smurfy]

I should clarify here that I was talking about lubing the race of small bearings on the wheel-end of the freehub body, that sit under a rubber ring-shaped dustcap. Not sure if that was clear to everyone, but thanks for the responses anyhow.

Sounds like you are describing the wheel bearings here ^^^^^^

If the chain is going slack then in my opinion that indicates a freehub body or jockey wheel problem. Grease in the wheel bearing shouldn't make any difference, because the inner part of the freehub body forms the cup part of the wheel bearing, and that rotates with the wheel. It is the friction between the inner and outer part of the freehub body that may be causing a slack chain. However, most people never break down item 18 (freehub body) into its individual parts. As I said before, it contains large numbers of small bearings, and even Sheldon advises not to bother.

 

[robjh]

Sounds like you are describing the wheel bearings here ^^^^^^

If the chain is going slack then in my opinion that indicates a freehub body or jockey wheel problem. Grease in the wheel bearing shouldn't make any difference, because the inner part of the freehub body forms the cup part of the wheel bearing, and that rotates with the wheel. It is the friction between the inner and outer part of the freehub body that may be causing a slack chain. However, most people never break down item 18 (freehub body) into its individual parts. As I said before, it contains large numbers of small bearings, and even Sheldon advises not to bother.

No, I've been talking about the freehub body all along.
You can see the bearing race in this picture (from the Bikeradar site)

But anyway, something troubles me about my own hypothesis : the resistance to backpedalling is only noticeable in the smallest sprockets, and only at some speed - worst on 11t sprocket, a bit less on second sprocket, and OK by 4th or 5th. Very slow backpedalling is fine even in the smallest ones. So there you might well suspect a misaligned derailleur/jockey wheel, but I can't see anything odd there despite lots of adjustment and checking.

 

[robjh]

[QUOTE 4140287, member: 45"]Have you dropped the bike on the chain side?[/QUOTE]
Not that I know of. You thinking of a bent derailleur hanger?

 

[Ajax Bay]

@screenman will say it's RMA Rear Mech Alignment.

Have you checked hanger alignment?

 

[Smurfy]

But anyway, something troubles me about my own hypothesis : the resistance to backpedalling is only noticeable in the smallest sprockets, and only at some speed - worst on 11t sprocket, a bit less on second sprocket, and OK by 4th or 5th. Very slow backpedalling is fine even in the smallest ones. So there you might well suspect a misaligned derailleur/jockey wheel, but I can't see anything odd there despite lots of adjustment and checking.

Surely that is because the gearing means that smaller sprockets spin the freehub body faster (for the same back pedalling RPM) so you are more likely to experience problems with a slack chain.

You could try to test this hypothesis.

1. Note the approximate back pedalling RPM that causes a slack chain on the 11T sprocket.
2. Switch to a 22T sprocket (or nearest available) and see if by doubling the back pedalling RPM you can make the chain slack.

However, the only problem with this test ^^^^^^ is that in larger sprockets the rear mech will be slightly more stretched, and the chain will be slightly tighter, so a slack chain will occur less easily.

Have you tried removing the chain and checking the jockey wheels rotate freely?

 

[raleighnut]

Surely that is because the gearing means that smaller sprockets spin the freehub body faster (for the same back pedalling RPM) so you are more likely to experience problems with a slack chain.

You could try to test this hypothesis.

1. Note the approximate back pedalling RPM that causes a slack chain on the 11T sprocket.
2. Switch to a 22T sprocket (or nearest available) and see if by doubling the back pedalling RPM you can make the chain slack.

However, the only problem with this test ^^^^^^ is that in larger sprockets the rear mech will be slightly more stretched, and the chain will be slightly tighter, so a slack chain will occur less easily.

Have you tried removing the chain and checking the jockey wheels rotate freely?

It's not so much that as the fact that the chain can exert much more torque on the hub from a bigger sprocket (more leverage)

 

[Smurfy]

It's not so much that as the fact that the chain can exert much more torque on the hub from a bigger sprocket (more leverage)

I agree that could be a factor. However, in the past I have encountered knackered freehubs that gave a slack chain when back pedalling fast, but not when back pedalling slowly. Same sprocket both times, the only difference was higher/lower back pedalling speed.

 

[Transporterman]

How did you get the hub back together yet Robjh? I've got a 3 speed Nexus hub in bits at the moment. It's on a spare wheel that I haven't been using because it's noisy. Actually it's probably going to be scrap because I found the bearing track looks in poor shape. But fiddling about with it the other day I couldn't see how you keep the pawls pressed in while you refit the unit back into the outer hub. There certainly doesn't seem to be any room to get screwdrivers in there.

Incidentally the bearing track that's worn is the larger one with the caged ball bearings shown in Smufty pic above.

 

[Pat "5mph"]

I would pry off the seal, flush with degreaser, fully dry, then re-lube. Finish Line Wet would probably work fine (that's what I used), or you could try car transmission oil if you have some.

Trying to get to the bottom of a noise, I did dismantle my back wheel, assisted by this video.
After watching I discovered my freehub has sealed bearings, so not relevant to me, but @robjh the guy was using a thin oil, he called it by an American name so I'm not sure what it is. Skip the bits about removing the cassette, the rest is relevant to you.

 

[Ajax Bay]

@Pat "5mph" The oil used in the video (at about 5.55) is Phil Wood's Tenacious Oil - described in the video as a 'heavy oil, kinda sticky'.

Trawling through a few threads: "Phil's Tenacious Oil is basically a re-packaged bar and chain oil. Bar and chain oils are used on chainsaws and are a light oil with additives to make it adhere to metal better. The idea is to have a "sticky" oil that won't get flung off a moving chainsaw."

 

[raleighnut]

@Pat "5mph" The oil used in the video (at about 5.55) is Phil Wood's Tenacious Oil - described in the video as a 'heavy oil, kinda sticky'.

Trawling through a few threads: "Phil's Tenacious Oil is basically a re-packaged bar and chain oil. Bar and chain oils are used on chainsaws and are a light oil with additives to make it adhere to metal better. The idea is to have a "sticky" oil that won't get flung off a moving chainsaw."

Works very well on Bicycle chains too.

 

[midlife]

Are you talking about the wheel bearings ? They have no effect on the freehub "sticking". Or am I getting the wrong end of the stick as usual....

Shaun

 

[Pat "5mph"]

@Pat "5mph" The oil used in the video (at about 5.55) is Phil Wood's Tenacious Oil - described in the video as a 'heavy oil, kinda sticky'.

Trawling through a few threads: "Phil's Tenacious Oil is basically a re-packaged bar and chain oil. Bar and chain oils are used on chainsaws and are a light oil with additives to make it adhere to metal better. The idea is to have a "sticky" oil that won't get flung off a moving chainsaw."

So what should the OP do? Buy chainsaw oil? Could you not use something that we would have already, like chain lube? Maybe wet lube because it is stickier?
Thank you for taking the time to write the above detailed response btw, very informative, but there was no need to link to bike lube and chainsaws, I think every member of this forum, even old bodging bike mechanic cat ladies like me know what they are
On the other hand, did not know of that brand of body oil ... and still don't know what "Tenacious Oil" is called here in the UK

 

[cyberknight]

So what should the OP do? Buy chainsaw oil? Could you not use something that we would have already, like chain lube? Maybe wet lube because it is stickier?
Thank you for taking the time to write the above detailed response btw, very informative, but there was no need to link to bike lube and chainsaws, I think every member of this forum, even old bodging bike mechanic cat ladies like me know what they are
On the other hand, did not know of that brand of body oil ... and still don't know what "Tenacious Oil" is called here in the UK

I am going to have a go with wet lube, the ( shh ) halfords stuff i have atm certainly looks the right consistency.

 

[robjh]

Are you talking about the wheel bearings ? They have no effect on the freehub "sticking". Or am I getting the wrong end of the stick as usual....

Shaun

How did you get the hub back together yet Robjh?

See the picture in post #20 above. The Shimano freehub bodies I'm talking about have a set of small bearings at the back, below a rubber seal that you can prise off quite easily with a screwdiver, and they go back on easily too.

I haven't actually taken it apart again since making this post, as the sticking is not proving a great problem in practice as I don't backpedal at speed, but I'm following the discussion about oils and will get round to it sooner or later.