I ride a 5 year old commuter bike with a Shimano Nexus 8 internal hub gear, that's done about 20,000km.
I'm not sure if I'm imagining it, but it seems like my bike has lost a considerable amount of mechanical efficiency recently. I now seem to be the slowest bike on the road; everybody passes me and I never overtake anyone, despite keeping the types pumped and the chain lubed. I don't ride any other bike, so it's hard to benchmark, but it feels like the hub slips a little inside as it operates, compared to the feel of a derailleur.
Engagement and changes is still 100% reliable in all 8 gears however.
Is this a known problem with ageing hub gears? Has anyone had this kind of experience before?