azad said:
qwerkus said:
An IGH has already non negligible friction losses, which can push the total to 12-13% in case of your Inter-7. human power is the tighter resource on a bike/ebike: don't waste it to pure friction losses.
So save yourself some troubles and keep your chain. With the extra money, ditch that garbage Inter-7 and get an alfine, or an Inter-8 premium (not the classic). Worlds of difference.
Does that mean IGH is less efficient than an external freewheel/cassette hub? I haven't replaced the external hub wheel yet and was infact hoping to get better performance with Inter-7 but if it is even going to be worse then I guess I made a mistake for buying a new wheel with nexus 7.
This is an ongoing debate. A good start is this article: https://www.sheldonbrown.com/internal-gear-theory.html See the two last sections.
The usual statement is: a clean and well lubed chain with optimal tension will reach an efficiency up to 98%-99% on a derailleur. Nothing else will ever beat this because of the simplicity of the setup. Now that's under lab settings.
Real life is a different story. Of 100 bikes I might encounter during a trip, ONE might show signs of a perfectly maintained derailleur transmission. All other ones are rusty, filthy, bent, under-tensioned or worse. In those case I doubt they reach 90% efficiency, and those people would be better off using an IGH.
So my bottom line is: if you count not only pure mechanical efficiency, but also time and energy of maintenance, cleaning and swears lost over chain drops, a good IGH beats hands down any derailleur. That's why I switched to IGHs on most of my bikes. Best choices are nexus inter-3 disc, newer nexus inter-5, alfine 8 and of course the paramount rohloff. On e-bikes, enviolo shine too because of their ability to switch gears under load, although 1kg heavier than the competition.
The inter-7 you mention is a swampy piece of hardware if you ask me. You can literally feel the drag when pedaling, that's why I would never recommend it. Best 7 speed was the now discontinued sachs 7 but it would not last one trip with a bafang mid drive.