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I Googled for this, but couldn't find the proper torque (in Newton-meters) for Shimano Alfine 8- and 11-speed IGH axle nuts. I'm putting the hub back on the bike after removing the rear wheel.
I'm no techie, but I read that an IGH must be tightened to the correct torque, neither too tight (risk of damaging the IGH) nor too loose (speeds won't change correctly).
What is the correct torque for these nuts?
Here is how I found the answer (30-45 N-m):
Followed the link in the first comment on the question (or I could have done a search for something like "shimano alfine hub service pdf").
The link Gordon provided was led to several Shimano products identified only by part number, so I did another search for "shimano alfine 11 hub" and found a listing on Amazon with the part number (SG-700). Shimano's part numbers are pretty transparent – if you know the two letter code that they use for different components – so you might be able skip this step with a lucky guess.
From there I opened up the service manual and scanned it for the step where the cap nuts are tightened.
Supplementary information (because the OP question and the answer may mislead some people reading a bit too fast): When putting the rear wheel back on the bike, the tightening torque only matters because it'll prevent the wheel to unscrew itself with the vibrations. This torque could be very high without affecting how the gears change inside the hub, since the pressure will simply squeeze the frame between the hub bolts and the wheel bolts. Now the bolts that should not be overtightened for an IGH are the hub bolts themselves (the ones you see once you remove the sprocket and possibly some cover on the other side). If you have removed the hub internals from the wheel to clean/grease/replace them, when putting them back in place you need to screw these bolts properly again. Don't overtighten, because the hub won't spin easily and you'll quickly wear out the ball bearings (and your leg muscles). Now if you undertighten, wobbling will eventually damage the hub internals. For these hub bolts, the service manual only states "thighten so that the hub moves freely and without play". Don't mix the torques because this latter torque is light and certainly much less than 30 Nm...
