Why are Shimano hub bearings tight from the factory?

[Abradable Chin]

I bought a new QR Deore hub, and I could feel cogging as I turned the spindle. I imagine the hub life would be severely reduced had I ridden it like this. Now, either the manufacturer knows about this, but doesn't care, or they can't find or afford a solution. If they don't care, why do they invest any money in design and analysis at all? Why do they persist with using cup and cone bearings on the basis that they give a lower contact pressure, and a longer life? I'd be surprised if they couldn't find a process solution to measure play in the spindle. Even hand adjustment shouldn't take more than a few seconds if it was all set up in a jig.

[Brucey]

Colin pointed out to me several years ago that the bearing adjustment probably changes between a loose hub and a built wheel because of the load on the hubshell. I've since tested this hypothesis and he is quite right, that is exactly what happens. The correct bearing adjustment will also vary with how tight the QR is. The correct setting is of course a little free play that just disappears when the QR is done up.

As to 'why the wrong adjustment', I think they have an impossible task to set them correctly, and the one thing the bike manufacturers won't accept is a hub that feels loose when the bike is slung together.

So, too tight it is, then....

cheers

[Gattonero]

To be fair, I've seen that Shimano hubs have gone a little bit down recently.

OTOH, if the price was right for you, adjust it as you like and is still good value? If the bearings were set so tight that have actually damaged the cones, ask for a refund, it should be easy to demonstrate you haven't adjusted by yourself when no marks are visible on the flats of the cones.


I'm not sure the bearing will change settings once the wheel is built, as the races are steel pressed in the alluminium hubshell they don;t actually "stretch". Besides, one is not supposed to exceed a certain value of spoke tension.

[Brucey]

...I'm not sure the bearing will change settings once the wheel is built, as the races are steel pressed in the alluminium hubshell they don;t actually "stretch". Besides, one is not supposed to exceed a certain value of spoke tension.

this definitely happens; the centre barrel of the hub is under about 200kg load (or something) axially from the spokes and aluminium isn't very stiff, so the hubshell elastically deforms a small (but significant in terms of bearing adjustment) amount.

The easiest way to quickly demonstrate this is to cut a hub (with no slack in the bearings) out of a wheel. The hub bearings are always tighter once the spokes are gone. You will feel this most easily in a less expensive hub, because changes in preload mean changes in smoothness when you turn the axle.

cheers

[Abradable Chin]

Rats! So I'll probably need to tighten the cones again once I've built the hub into a wheel, and I've improperly maligned Shimano. Sorry Shimano.

[foxyrider]

Rats! So I'll probably need to tighten the cones again once I've built the hub into a wheel, and I've improperly maligned Shimano. Sorry Shimano.

Never a bad idea to strip and reset the cones in a new hub anyway and as for maligning Shimano - well it was their stuff kept breaking on Froomies bike!

[SA_SA_SA]

Would it be stop hubs rattling in Transport?
Do Shimano not expect the cycle manufacturer to adjust the QR hub after wheel built and placed in bike?

[Brucey]

Never a bad idea to strip and reset the cones in a new hub anyway....

essential, IMHO.

The adjustment is always wrong as discussed, and the grease that shimano uses is in no way proof against the UK weather.

Very occasionally I open up a used shimano hub and find that the OEM grease is still clean, and the seals are not worn. This happens so rarely that it is a special and memorable event...

cheers

[scottg]

Sheldon has a neat hack to adjust the cones under compression,
scroll down a bit.

https://www.sheldonbrown.com/cone-adjustment.html

[Brucey]

Sheldon has a neat hack to adjust the cones under compression,
scroll down a bit.

https://www.sheldonbrown.com/cone-adjustment.html

Sheldon suggests using an old cone(with a short length of axle inside it) to load the axle whilst leaving the locknuts free for adjustment



However it is usually possible to do the adjustment with the axle under load more simply than that:

If you temporarily install the QR skewer from the right, without springs, but with a few M10 washers installed at the RH end, when the QR is tightened, the QR nut will usually bear against the LH axle end in such a way as the locknut and cone are still free to be adjusted using cone spanners. If for some reason (eg nut has deep recess, axle protrusion is shorter than normal) this doesn't work you can instead use

a) a few M5 washers as packing between the QR nut and the axle or
b) a standard M5 nut instead of the QR nut. (except some older Maillard hubs which don't use a standard M5x0.8mm thread)

You can tell when the adjustment is 'perfect' because the bearings will develop free play when the QR is only half-tight. If there is no free play with the QR any looser than this, the adjustment is wrong.

Sheldon suggests the adjustment accuracy ought to be 1/10th of a turn (or better ) but in fact 1/100th of a turn is probably more like it.

cheers

[Gattonero]

...I'm not sure the bearing will change settings once the wheel is built, as the races are steel pressed in the alluminium hubshell they don;t actually "stretch". Besides, one is not supposed to exceed a certain value of spoke tension.

this definitely happens; the centre barrel of the hub is under about 200kg load (or something) axially from the spokes and aluminium isn't very stiff, so the hubshell elastically deforms a small (but significant in terms of bearing adjustment) amount.

The easiest way to quickly demonstrate this is to cut a hub (with no slack in the bearings) out of a wheel. The hub bearings are always tighter once the spokes are gone. You will feel this most easily in a less expensive hub, because changes in preload mean changes in smoothness when you turn the axle.

cheers

I think it's not easy to calculate that.
Were the spokes radial laced, one could take the burden of extrapolate 100kgf times 32, minus the angle they are between the rim and the hub (quite steep) and the difference in between the curve of the hub shell.
It's an interesting theory, but in practuce I've never noticed suh a difference as what an inflated tyre can do.

[Elizabethsdad]

I don't suppose this is the reason at all, but it occurs to me that by shipping out the hubs in a stiff to turn state means to end user will more likely notice this and set them correctly. If they were sent out less tight, they would more likely get used as is, which might be a bit too loose.

[Samuel D]

I think they’re shipped too tight because (a) correct adjustment is impossible to guess, (b) too loose would complicate wheel-building, (c) if you have to ride the bicycle with the preload too loose or too tight, the latter is better within reason, (d) people use higher quick-release tension than Shimano expects, and (e) if the hub does die earlier than it should, Shimano’s stranglehold on the market means it’s likely to win another sale, so there’s no urgency to make more accurate estimates about the preload likely seen in service.

[Brucey]

I think it's not easy to calculate that..

it is very easy to calculate the axial load, and estimating the axial deformation is not difficult either. What is less easy to know is how the cups in the hub deform radially, once the flanges are loaded. I think the radial deformation is going to be a lot smaller than the axial one, but it all adds up.

I don't suppose this is the reason at all, but it occurs to me that by shipping out the hubs in a stiff to turn state means to end user will more likely notice this and set them correctly. If they were sent out less tight, they would more likely get used as is, which might be a bit too loose.

That might make some sense for the aftermarket, but were it so, they could presumably just as well ship the hubs with the LH cone and locknut loose... The vast majority of shimano hubs are fitted to factory-built bikes and the one thing they will not tolerate is loose bearings, because time is money and it makes building the wheels more time consuming if the bearings need to be adjusted. If they give a thought to the bearing adjustment at all, it will be that the LBS ought to set the hubs up, and (cynically) provided they don't come back as a warranty claim, they don't really care.

It is also possible that, having copied the design in the first place, but omitting the tab washers that were in every other implementation of it at the time, that they don't/didn't really understand all the design features required in a cup and cone hub. All shimano hubs are, in hard use, vulnerable to the same thing, which is that in service the RH cone precesses inwards and wrecks the hub. Whilst not all tab washer/shouldered axle arrangements are 100% proof against that, they are at least a tacit recognition that there is an issue of this sort.

Further evidence that this might be the case is readily available in the form of the most recent of Shimano's cup and cone designs, which use a fat aluminium axle. These are meant to be 'easy to adjust'. Well, they are most certainly no such thing, not if you want to do a proper job; they are just as vulnerable to the effects of QR compression as any other QR cup and cone hub, but because of the daft design (and unlike every other cup and cone hub ever) there is no possibility of having the QR load on the hub whilst the adjustment is being made. To get the adjustment spot-on, the QR has to go in and out of the hub about a dozen times before it is correct. Stupid Stupid Stupid....

cheers

[colin54]

I had a look for some pictures of the hubs being manufactured, I couldn't find any Shimano ones but these pictures of Novatec hubs

being made are quite interesting.

I had a set of wheels built a while back, I still stripped the hubs regreased and adjusted, there was a scarily small amount of grease in

the rear hubs ( Shimano LX), I wouldn't imagine wheelbuilders strip hubs as a rule.

This is a problem with pedals as well, I wonder if a lot of these parts are machine tightened to a minimal torque setting to just remove

end play.

https://www.pinkbike.com/news/Making-a- ... -2013.html