FarHorizon

Having picked up a 3-speed, I notice that the rear hub makes a "whirring" sound when coasting (particularly at higher speeds). I'd taken it to the local bike co-op where the mechanic (who isn't highly experienced with internal-gear hubs) opined that the bearings might be set a tad too tight.

On the following day, I took the bike to the LBS that is the official dealer for this brand (on another issue) and they put it on the stand. While testing the cranks / bottom bracket, they spun the rear wheel to speed (multiple times) and let it spin down. They didn't mention the noise nor did they comment on the wheel being tight (and I forgot to ask).

So my question is, how does one assess bearing adjustment on multi-speed, internal-gear hubs? Is a slight whirring "normal" when coasting? What bearing maintenance (if any) is needed for internal-gear hubs? And if I'm to adjust the bearings, should I adjust those on the drive or non-drive side?

The hub under discussion is a Shimano Nexus 3-speed.

Thanks - FH

FBinNY 

IGH hubs have a planetary gear train inside, that is engaged and spinning, regardless of the gear you're in or power flow within the hub. So the whirring you;re hearing is probably that, and not in any way related to the bearing adjustment. In any case ball bearings usually don't make a whirring sound for any reason.

FarHorizon

Thanks, @FBinNY - That answers all the questions in one. That being the case, then no worries - just ride!

Andrew R Stewart 

Bearing play in an internal geared hub is much like an external geared one, with a few caveats. One is that there's a lot going on in an internal hub so some slight looseness in the bearings is not uncommon. Once the wheel in secured in the frame and the rim is grabbed and wiggled side to side a mm or two of play isn't wrong. Second is that many internal hubs want one side's cone/locknuts to be located a certain distance from the axle end or other feature. So adjusting the bearing play isn't always the same as with a freewheel, cassette or coaster hub.

As to the friction or inefficiency of an internal hub it is usually greater then other designs. As an example with the SA AW the second gear is direct drive (no reduction or increase due to the planet/sun gears being in play) and has greatest efficiency. Some will choose cogs and rings to be in this gear when possible. Some books have more info about tests for this. Of course any data from the manufacturer must be assumed to be under "ideal" conditions.

I don't bother to memorize the adjustment steps for the various brands and versions of internal geared hubs. I leave that for a goggle search and tech manuals. Andy. (who does know SA AWs pretty well but still cant overhaul them blindfolded).

FarHorizon

Thank you also, @Andrew R Stewart - I've decided that if the issues get worse, I'll dump it on my LBS. I strongly suspect that their "repair" will be to replace the hub and wheel with a new one! LOL

fietsbob

Hills (gravity) and air resistance are Greater .

at both ends of the hub is a cup and cone bearing .. had 3 S-A Hubs in past 50 years . 2 AW & 1 BSR. all trouble free..

Retro Grouch 

Internal gear hubs have constant gear-to-gear contact which is less efficient than roller chain drive under perfect conditions. How much less efficient is the question and you might need laboratory grade instruments to calculate the difference.

This fact, however, is always present: Once you get over about 15 MPH on a flat road, the energy that's required to push your torso through the air exceeds everything else that's holding you back combined. It's fun to argue on BF about the relative efficiency of internal gear hubs but in real life it doesn't matter.

dynaryder

Some hubs are also louder. I've had a couple SRAM i-Motion hubs(3 and 9spd) that were noticeably louder than any of my Shimano(3/4/7/8spd) hubs. Never had any issues,they just sounded different.

Seizedpost

Sorry to bring this thread back from the dead, but I have the same question. I'm fixing up a 1967 Hercules with a Sturmey Archer 3 speed, and there's noticeably more resistance when freewheeling than with a regular freewheel. It sounds like this is normal, correct? It still spins for a while on the stand, just not as long as a freewheel. I don't think the cup and cone bearings are too tight because there's no noticeable extra resistance on the stand when pedaling in second gear.

FBinNY 

Yes, IGH hubs have some internal resistance that FW and freehubs don't. It's impossible to quantify becayse there are too many variables including the amount and viscosity of oil within, and even what gear it's in.

However keep in mind that unloaded drag is very small compared to the reality of loaded drag, and total drag which is more about wind than anything else (depending on speed). So, double a negligible amount of drag is still negligible.

Schwinn me

The extra drag of IGH hubs and tire driven generators for that matter is mostly psychological and that translates into a real world fatigue. The more you focus on the noise coming from these components, the sensation of drag and fatigue intensifies.

HillRider

Rohloff has a rather extensive article on IGH hubs efficiency on it's web site: https://www.rohloff.de/en/technology...ncy/index.html

As with most of these issues, the answer is "it depends".

Robert C

This chart shows up during a lot of searches. There is another on that I cannot find. it included several different IGH and the NuVinci, along with conventional drive-trains.


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