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Missing oil drain plug

The Shimano Nexus gears cannot be maintained by lubricating with oil as gears with oil drain plugs such as the Shimano Alfine 8. The only way to do this is to dismantle the entire hub and immerse the planetary gear unit in motor oil. However, with a common city bike, this is a dirty hands job of more than 3 hours.

I have found a solution: I drilled a lubrication hole of 5mm, by which the hub can be lubricated easily from the outside. It appears that a piece of good duct tape is sufficient for sealing. A sealing screw is of course nicer, but difficult to make.

Drilling an oil drain hole in the Shimano Nexus 7
Drilling an oil drain hole in the Shimano Nexus 7

The big friction problem of Shimano hub gears.

The Shimano hubs are mounted on many bicycles. What many people don't know is that Shimano hub gears require a lot of extra pedaling energy, I have personally experienced this with my Gazelle city bike. On my old city bike with an efficient 3 gear hub, I easily cycle 25kmh, but with the same effort I can't drive faster than 20kmh with my city bike. This is very frustrating. The cause of the high friction is the poor quality of the inside planetary gear.

The Nexus 7 is most notorious for its poor efficiency, so, avoid this hub. The Shimano Nexus 8 and the Alfine 8 also have serious friction but in the most used gears this is less bad than the Nexus 7.

Shimano Nexus 7 big friction problem
Shimano Nexus 7 big friction problem

The Shimano Nexus gears are lubricated with grease instead of oil.

By the factory, the Shimano Nexus gears are lubricated for life with grease. It is not the intention to be lubricated periodically otherwise they would have an oil drain plug. The grease is syrupy and this is one of the reasons of the high friction.

Maybe the friction of the Shimano Nexus can be reduced by removing the grease and using thin oil for lubrication. Can anyone try this out?

After lubrication the friction does decrease but the friction is still greater than the best hub gear: the Rohloff Speedhub.

Drilling the oil drain hole in the Shimano Nexus

Keep the gear clean when drilling
Keep the gear clean when drilling

Drilling the oil drain hole in Shimano Nexus 7
Drilling the oil drain hole in Shimano Nexus 7

Drilling the oil drain hole in Shimano Nexus 7
Drilling the oil drain hole in Shimano Nexus 7

Duct tape is sufficient for sealing.
Duct tape is sufficient for sealing

Shimano Nabenschaltungen im Vergleich
Shimano Nexus/Alfine 3, 4, 7, 8, 11 Speed Hub Technical Information

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