This something that everyone says but I’m not sure I agree. Rain shouldn’t make the brakes wear out any faster than dry. The grit is there no matter what. If anything, rain should keep the dust down so that the wheels don’t have as much dust on them as the water washes it off.

I’ve also done a lot of mountain biking here fenders are a liability and dirt is ubiquitous. I’ve only worn out a couple of rims in 40 years of riding.

I also can’t agree with this. Again, from mountain biking with unfendered bikes, I have never had a sealed cartridge bearing bottom bracket wear out of any flavor. I’ve replaced a lot of them through upgrades but I’ve never worn on out. I also see a lot of cartridge bearing BBs at my local co-op and have only seen a few that aren’t functional. Most of the used ones we have could go several years without issues.

It’s not the rain that causes problems with spoke nipples. It’s probably salt, especially with bikes like the one in your picture. Snow is almost always accompanied by salt application and that is going to corrode steel, aluminum and brass. When steel is in contact with either aluminum or brass and in the presence of chloride ions, bad things happen. Chloride ions are particularly good at oxidizing both aluminum and iron. A good spoke prep and oil used during lacing and tensioning will go a long way to avoiding corrosion problems.

I don’t run full fenders on my bikes but I have to agree. I have Phil Wood hubs that have 20,000+ and 10,000+ (two different sets) on them with zero maintenance and zero problems. If something does go wrong, the cartridges are easily replaceable. Same can be said for my bottom brackets, headsets and even pedal bearings. Why even mess with loose bearings?

The issue isn’t about certain kinds of weather, or the use of sealed bearings vs non. It’s all about foresight, preparedness and diligence.

A few few points:
1. Not all cartridge bearings are ‘sealed’. And referring to a cartridge bearing as a ‘sealed bearing’ is wrong. There are also plenty of loose ball hubs and bb’s that have seals to help prevent ingress. How well all of these work is.. well do you trust the water resistant seals in your watch or your ‘weatherproof’ camera? How about that new smartphone? Yea me either. And the seals in a proper sealed cartridge bearing are just as effective or not as other seals. The best prevention of ingress is multiple-stage seals, like SKF bb’s use, for example.
2. Most corrosion that occurs though, occurs long after your ride in the rain. This almost always comes from simply leaving a bike wet. The best way to prevent this is by simply drying the bike after it’s been ridden in the wet. I’m a commuter, and as such I always carry a hand towel to completely dry off the bike, especially on parts that are more prone to corrosion. Chromed steel is a big one. Don’t let the bike air dry, especially in a cold or humid enviroment and be surprised you got rust. And if theres rust where you can see, there’s likely more rust where you cant.
3. Use quality grease, especially this time of year. But nothing is more important than diligent maintenence. Doesn’t matter if you have all ‘sealed bearing’ everything or loose ball bearing everything. Take things apart, inspect them and if necessary clean and re-grease them. If you’re doing a lot of riding in the rain, I would recommend this every two to three months, especially if you’re usibg loose ball bearing components.
4. Excess wear of brake pads and rims, is heavily dependent on where you live, but in general, water and other debris get mixed together with the brake dust that’s already on your pads and rims, when wet. This creates a bit of a ‘slurry’ that will also contain whatever is on the road surface, trapped by the rain and kicked up by your tires. (Obviously things like full coverage fenders and even a fully enclosed chaincase make a massive difference here. They were invented for a reason.) in my case that extra ingredient is sand, as I live on the southeast coast of the US. In dry weather it’s no biggie, in the rain, it becomes a big biggie. And it will absolutely create excess wear to pads and rims. Don’t believe me? Ride a pair of black anodised rims with rim brakes in the rain. Nothing you can do to avoid it in the moment, but when drying off your bike after the ride, do a quick wipe down of both the rims and the pads to remove any debris.
5. Check everything! Don’t just focus on the obvious, like headsets and hubs. Check pedal bearings, freehub bearings, remove seat post and stem periodically (use framesaver in a steel frame). Remove and clean cassettes. Also remove tires and check for moisture on the inside of rims. Certain rim tapes (cotton tape like velox) can soak up and trap moisture and can corode nipples and eyelets.
6. This is especially important on older (like C&V) bikes: If you can replace chromed, galvanised or regular steel fixtures, like bolts, with stainless, do it. Stem bolts, chainring bolts, binder bolts, etc. Also, stainless cables and housings are always a good idea, as is a stainless or nickel plated chain.
7. Clean your chain, regularly. Seriously. And don’t over-lubricate it. Use a lubrication designed for use in wet conditions, but use it sparingly.

this time of year, where I live sees a lot of rain. I install fenders, but my daily rider/commuter has loose ball track hubs, loose ball bb, loose ball pedals, cartridge bearing headset, a cartridge bearing freewheel, rim brakes and a leather saddle. I replaced my chainring bolts for stainless, I use stainless cables and housings and a stainless chain (connex). A 41 year old steel frame with chrome. no corrosion and no worries. Also, no need for a ‘beater’ bike. Those type of bikes are for people who are too lazy to properly take care of what they own.