Raleigh71

One thing I've noticed many times is that when a bike is up on the repair stand, when I set the wheel spinning and as it spins, the freehub (or freewheel too) seems to float a bit in a circular manner. I've checked the axles and they're not bent. Is it the freehub body with a bit too much play wearing out or damaged?

xenologer

Because the bearings inside the freehub body are askew from the bearings of the main hub/axle.
Thus as the hub turns underneath the freewheeling freehub body, it cannot maintain a perfectly centered position and you see wobble or 'float'.
Now that you've seen it, it will haunt your dreams forever.

MudPie

Freehub / freewheel float (or oscillation) is not uncommon. I think every bike I've owned had a little. I'm guessing it's the result of machining- difficult to ensure perfect concentricity among many moving surfaces. In other words, it's darm hard to align the axis of all parts perfectly. Parts could easily be 0.003" off of the theoretically perfect axis, and this little eccentricity gets exaggerated the further you move away from the axis..

FastJake

+1

Almost every freewheel/freehub I've seen wobbles a little. Even new ones. Don't worry about it, it's not a problem.

mrrabbit 

https://www.youtube.com/watch?v=OI6JxL-zjXc

My YouTube video for freewheel wobble applies...same off-center machining is behind freehub wobble and float as well - not just for the race machining in the shell - but the threads or mount point for the freehub as well.

=8-)

2manybikes

They all do it.

FBinNY 

Not true. It depends entirely on the design and construction of the hub.

The design of Shimano and many others has a self contained freehub module attached to the hub shell. With this design the "axle" of the freehub turns with the hub shell and because perfect alignment isn't possible the rotating freehub "axle" will oscillate slightly taking the freehub and cassette with it.

Campagnolo and others use a different design wherein the hub turns on 2 bearings and the freehub body on it's own two bearings. The freehub body is connected to the hub only through the freewheel ratchet, and so is totally stationary when coasting.

Neither design is better or worse, just different, and freewheel oscillation has been around for decades, and causes no issues.

mrrabbit 

All loose ball bearing freewheel type and freehub type hubs have the potential for "wobble" or "float".

1. Quality Control typically keeps it down to low-end or entry level hubs.
2. Off-center race machining of the shell is a major cause.
3. Off-linear thread machining of the threads on the shell for freewheels is another cause.
4. Off-center thread or mount-point machining for freehubs is another.

=8-)

The potential is there for sealed-cartridge bearing equipped hubs as well - but the negative impact on the bearing units is such that most if not all manufacturers will not let the hub out the door.

canam73

+1.

Raleigh71

Thanks for the input

Yeah, it has been haunting me for years.

Not enough for Prozac,

Now this guy needs Prozac, or at least a better bike rack:

See jpeg.

Click for a larger image:

sametheman576

It actually helps with index shifting. But thats not why it does that.

neurocop

mrrabbit has it exactly right. The "wobble" is due to mis-allignment of the hub shell bearing surfaces, not "slop"in the freewheel. Check out his link. The bottom
line is that this wobble is both common and practically inconsequential. The fact is that freewheels screw on tightly to the rear hubs. I suppose that a "sloppy" freewheel could wobble on a perfectly alligned rear hub, but such a sloppy freewheel would be obviously loose on inspection. I've mounted perfectly functioning freewheels to slightly out-of-line hubs and seen them wobble.

Looigi

Correct. None of the 8 hubs I have here across road and mtb wheels exhibit any perceptible wobble of this type.

Nick Bain

well my bearings are shot on the drive side (the races are worn unevenly) , so I think I will worry about it. and yes it is your fault. Maybe if I crank the **** out of the mounting screw (without stripping it) it will sraiten up a bit.

Nick Bain

I would go along with that, now how can I realign it. My kysrium elite don't do that.

jaltone

A bit long winded, so pardon my loquaciousness. But I think it necessary to explore this thoroughly.

I know this thread is a year old, but I'm trying to understand this as I just bought a new WH-6700 wheelset that shows this characteristic. (I Googled and came upon this thread.) Can someone help me understand this clearly? This is my difficulty. When I am turning the crankarms the splines/cassette does not wobble nor float. This means that the line about which the splines/cassette rotates is exactly on the same line that the wheel hub rotates, yes? Am I correct so far? Now, when I grab the crankarms still and let the rear wheel freewheel, the splines/cassette wobbles. Does this mean that the line about which the freehub rotates and the line about which the splines/cassette rotates are different? And, if so, does this mean that the problem/misalignment is inside/within the freehub module itself? For if the line about which the freehub rotates and the line about which the splines/cassette rotates are one and the same, wouldn't the splines/cassette wobble both when freewheeling and when pedaling? And yet I see the splines/cassette wobble only when freewheeling, not when the crankarms are being turned. If there's an error in my logic can someone point it out (nicely 8-). Or explain to me a bit more so I understand why the splines/cassette wobbles only when freewheeling and not while pedaling?

Another way of explaining how I understand it is this. Due to manufacturing difficulties (mentioned in this message thread) the line about which the wheel hub rotates can be aligned most of the time only to either the axis of rotation for the splines/cassette XOR the axis of rotation for the freehub, not both (i.e., if both are aligned it's an unintentional, lucky rarity). Since it's more important that the cassette and wheel hub rotate on the same axis when pedaling, the freehub's rotational axis alignment is the one being sacrificed. Is this logic correct?

FBinNY 

.

Let me give it a shot using parts you are familiar with.

Forget the hub for a moment, and imagine you (for whatever reason) decide to attach a freehub to your crankset.

No matter where you attach it the freehub will spin true as long as the crank is stationary. But if the crank rotates (whether the freehub does or not) the place you mount it makes a critical difference. If you mount it correctly aligned at the center of the cranks, it won't move as the crank turns and all will be cool. But now imagine if you mount it in a pedal hole.

It will spin true on it's own axis, but as the crank turns it'll go up and down in a large circle.

Obviously hubs are built pretty close, but as I said earlier, it's very difficult to get the two centers of rotation (the hub's and the freehub's) perfectly aligned, so as the hub turns the freehub oscillates, or moves up and down in a twisty motion.

fietsbob

Aero-space levels of precision costs more than consumers at retail are willing to pay.

now if 100K$+ a bike is in your price range, then the number of out of tolerance discards goes up accordingly.

then the made but discarded stuff is part of the cost passed on to the end user.
that is the economics of rocket science.

jaltone

FBinNY, I carefully reread your (and others' as well) past and present posts. And with the aid of this diagram I found from further googling on the subject I now understand it.

Fietsbob, I'm not knowledgeable in manufacturing processes, but why can't tight tolerances possible in Japanese auto parts be made possible in Japanese bicycle parts? I'm not being argumentative. I'm just flabbergasted to see an Ultegra level component "work" this way. I mean, in my mind Ultegra is comparable to a Lexus, wouldn't it be? Besides, I think comparing it to rocket science is stretching it a bit. There's nothing on a road bike that's even close to being complicated as a gyroscope in a rocket's guidance system.

fietsbob

you show a screw on freewheel instead of a freehub in that page.

the tolerances are adequate in auto manufacturing you just dont see inside the motor while its running like you do with a bicycle drivetrain, out in the open

cassette sytems are better than freewheels because the freehub is part of the hub then the cogs slide on , they're sort of flat .

FBinNY 

It's not that greater precision isn't possible, it's a question of economics. It's very difficult to couple two parts together in perfect axial alignment, but it can be done, or at least to where the error wouldn't be visible to the naked eye.

But it would significantly raise the cost of rear hubs, while offering no mechanical benefit. Of course it might make some people happier to not see the gritty world of manufacturing tolerance, but this is one of those problems which no one would notice it it weren't visible.

IMO bikes are made for riding, not for obsessing about, and it's a mistake to look too closely at every little "flaw".

BTW- if this really bothers you, there are hubs that don't have this idiosyncrasy. Campagnolo, DT, Mavic (I think) and some others do not mount a modular freehub to the hub shell. Instead the freehub shares the axle and turns on 2 bearings to the right of the hub's 2 bearings, and is connected to the hub shell only through the freewheel ratchet unit. Since the freehub turns on a static axle it runs perfectly true.

jaltone

Fietsbob, FBinNY, much thanks for further expounding on it. I'm listening and learning. Fietsbob, I didn't even know the diagram had errors. I'm just desperate to see an illustration of what a freehub looks like inside. LOL. FBinNY, thanks for putting it in the right perspective. I'm now putting the subject to rest in my mind. You're right, I'm fussing over nothing really.

Chombi

Despite what we all think sometimes, bicycle component design and manufacturing is most of the time, not rocket science and that the manufacturers live with pretty wide tolerances with their component fabrication....so the ages old symptom of FW wobbling remains with us with almost every FW we encounter......Dang!, to think that I hated the French when I first found out that the FW on my Peugeot in the 80's dared to wobble when I spun the rear wheel!......only to find out a short time later, after checking out pretty much all the different bikes for different companies and countries in my LBS, that all pretty much did that to some degree.....
So in the end, as the old saying goes........"Nothing to see here, keep moving"......to other bigger "problems" that will actually affect your cycling....

Chombi

Amesja

How much is the average consumer willing to spend to "fix" this problem so that this heinous wobble can no longer be seen by the naked eye?

Since it has absolutely no effect on the actual performance of the drivertrain, other than a cosmetic wobble while coasting that most bicycle riders haven't even noticed ,then it isn't much.

jaltone

Amesja, you're absolutely right. The average consumer would probably never even notice it in the first place. It's these $!?@ recreational hobbyists/riders like me who do take notice, and ignorant that they are, freak out the first time they see it. What makes it worse is I'm an OCD, anal person who worries until questions such as, "Why does it do that? Is it supposed to do that?! Etc?" are answered to satisfaction. Usually though, after a sane person has pointed out how normal it really is, I calm down and then laugh at my silliness.

Then again, BF wouldn't be so lively were it not for crazy hobbyists like me, right? ;-) I hope everyone has a good day.