IGH Lifespan?
 

Almost anything with moving parts has an expected "service life". If it's designed well, the wear points will be under stressed and/or easily replaceable. Antique farm engines or Sturmey Archer 3 speeds come to mind. If you have a long production run and make a string of incremental improvements you can still make it repairable by modular design, tweaking sub assemblies instead of going "clean sheet".

I saw one review where a guy asked about the expected life of a Rohloff 14 speed and was told "As soon as somebody wears one out we'll let you know." This strikes me as pretty darn arrogant. *NOTHING* with that many moving parts is bullet proof no matter what miracle materials it's made out of or how high the price tag.

I live in a country where anything that expensive and portable would require an armed guard to keep it from getting lost. I ride for transportation and exercise so I need something reliable but want to avoid owning a theft target. Both of my bikes right now have Shimano Nexus Inter 3 hubs. Does anyone know how long I can expect them to last with reasonable care? I'm doing mostly stop and go traffic on level ground, averaging about 300 miles a month.

Wearout and breakage are two different things. I assume you are interested in availability, which is "can I use it?" Unavailability ("grrr I can't ride this bike!") can result from wear of (for example) a bearing or gear tooth face, and breakage can result from overstress, poor quality, poor design, et cetera.

If you're expecting the manufacturer to open his kimono, how much to you reasonably think you can learn?

Preventing wearout on the rider's end, after retail sale, is affected by lubrication, overhauls (maybe not so much for an IGH), sealing. If you do all that religiously the rates of component wear should be so low as to be essentially forever. Under those conditions lifetime can sometimes be predicted, but testing to confirm it can take a really long time. Testing to cover all the ways one may fail to provide maintenance after retail sale is even less easy. If you don't provide all the recommended maintenance, it's kind of a crap shoot.

With these contingencies, design life is not useful to know, even if Rohloff or Shimano will tell you what you think would be useful.

Maintaining proper adjustment is also important, so that the various pawls and other parts are correctly seated against their counterparts, distributing the load as intended. Many decades-old IGHs are still in service. I know that as a kid I totally abused my Sturmey-Archer 3-speed, shifting under load and slamming against the ratchets and I couldn't kill it. It could still be going strong although the frame has likely rusted apart.

Before i learned how to dissassemble/assemble SA AWs i rode one that was running on only one 1st gear pawl and a broken planet cog (the spring of the other pawl got mangled up by that planet cog). Apart from an occasional click everything worked fine.

Obviously my question was overly broad and I couldn't resist a swipe at a company making $1,000+ bicycle *parts*. They honestly haven't had time to accumulate any useful amount of real world data.

Lubrication is a huge factor. With a clean film of the proper lube metal parts don't actually touch. An old mechanic buddy told me once that with the adoption of electronic controlled fuel injection the average life of an auto engine just about tripled. The best carburetor ever built rarely delivered more than a close approximation of the correct mixture and the excess fuel washed lube off of moving parts on it's way to contaminating the oil supply. When I started driving, a 100,000 mile engine was toast. Today 300,000 with normal maintenance isn't unusual.

So let me revise the question.

Has anyone here experienced a failure of a Shimano Nexus Inter-3 hub? If so, was there any obvious way to avoid it? Things like a flush and re-lube after accidental submersion or pulling it out of long term storage.

The closest I can come is a Nexus 7-speed hub which I damaged by water incursion from too-aggressive washing (though this was unknown to me at the time). The hub probably had a couple thousand miles on it.
Once I learned this lesson, I have another 7-speed and two 8-speed Nexus hubs with about 14,000 miles between them; one of the 8-speeds has about 8,000 of those miles on it. These hubs are opened once a year and the gear clusters dipped in gear oil. The bearings are greased. The races look nearly new.
I also have an Alfine 11-speed hub on my newer commuter bike. This hub has 7,000 miles on it and has had no maintenance other than an oil change about every 700 miles (no disassembly required).
I'd expect a 3-speed hub to be at least this reliable.

Forever

The old (English built) Sturmey Archer 3-speeds were famous for going nearly forever if you did two things religiously. Put oil in the oil port and see to it that the shifting cylinder lines up with the axle end in 2nd gear. (Religiously doesn't mean often. A seldom ridden 3 speed will fare just fine if one religiously honors the above every February 29th. Once or twice a week use? Every February 28th.) I never heard of one dying when those were done.

Ben

There's a reason IGHs are specced on commuter bikes. Low maintenance.

Keep it lubricated.

https://forum.cyclinguk.org/viewtopic.php?f=5&t=93935

Still running my 1953 Sturmey-Archer AW hub on my city/commuter bike with no problems.

Excellent link! It answered most of the questions I had and several I hadn't thought to ask.

In my part of the Philippines we have a wet and dry season with fairly consistent temps. We're now in the wet season but that's relative. It simply means it's probably going to rain for a little while sometime in the next 24 hours. Dry season is when you can go 2 - 3 days between showers. What it means for the bike is that I'm not going anywhere without riding through standing water at some point. Average is 1 - 3 inches, sometimes as deep as six. I haven't soaked a bottom bracket yet but it's only a matter of time.

It looks like my best strategy is going to be heavy grease on the axle bearings to keep the water out and a monthly squirt of ATF in the shift pin hole to keep whatever does get in migrating outwards. I did the dip lube on my backup bike. The Albelt hasn't been lubed since some time before it left Japan. I'll be swapping out the belt for a chain and different set of sprockets some time in the next few weeks. I planned to do a clean and repack then but wasn't comfortable running on whatever was in there while waiting for parts. A few squirts of ATF has made a noticeable difference and lets me be a little more relaxed about waiting to open it up.

My 1936 AW is still a beautiful little piece of clockwork, but I have no idea of its service life, maintenance or repair history before I curated it.

I know the feeling. I've been a life long firearms enthusiast. There are rifles in production today that are basically Mauser model 1898's (with minor variations). I lived near Oshkosh, Wisconsin, where Basler flight service rebuilds and re-engines Douglas DC-3 aircraft. There are some pieces of machinery that seem to hit a sort of sweet spot in design and construction. It may be possible to improve performance with radical redesign but for what they do, they become benchmarks, still considered a "best of type" decades or even a century after they were first introduced.

Indeed, and the AW was designed at a time when high precision machining was not a practical technology for manufactured goods. Compared to typical modern designs, there is an incredible amount of "slop" in the fitting of the parts, yet the whole thing works flawlessly for decades. Another interesting feature is that the axles are harder steel than the axle nuts, so the nuts wear out and can be replaced but the axle threads last forever.

I had a friend with a M66 Ural motorcycle made in Russia, basically a crude copy of a 1930's BMW. It shifted like a tractor and he dumped about a tablespoon of metal shavings out of the strainer on the break in oil change. It's running much smoother now with close to 50,000 miles on it. The few issues he's had with it didn't require the services of a motorcycle mechanic. Any competent blacksmith could have sorted it out. :ride: