Recently I made a post on the Facebook Surly bicycle group that talked about passing 15,000 miles on my Long Haul Trucker. I mentioned that it was a stock bike. Some people took issue when I said, “The stem, bottom bracket, and hubs have never been unsealed and are in great shape for the next 15,000 miles.” Several recommended regular servicing of the hub bearings. I found an old post by Sheldon Brown that also recommended regular servicing. On the other hand, a mechanic at my bike shop recommended no action at about a 10,000 miles when I asked about hub and bottom bracket maintenance on my bike. Further research found that this is an unsettled issue in my opinion.
The brand and quality of the hubs may be a factor. That said, there are wide ranging opinions concerning the efficacy of various hubs. For example, my hubs are Shimano LX hubs and there are some detractors. There is a broad opinion that they are as good for touring as more costly hubs.
Next I tried to find evidence of hub failures. There is evidence of freehub failures on certain types of hubs, but those are not bearing failures. They are failures of the ratchet that locks the cassette to the hub when pedaling forward. I found one video that documented hub bearing failure on a fat bike. The type of hub is not identified and other actions that may have contributed to such catastrophic failure are not discussed. Component quality and brand may be a factor in such failures.
Here is my take. Modern hubs of moderate quality are sealed and there is evidence that they do not need regular disassembly, cleaning, re-greasing, or adjustment. There are some people on the Internet who talk about having similar mileage on their bicycles as I do and have not serviced their hubs. I am only one data point and other data points are rare.
There are things that you can do to compromise the hubs, such as pressure washing. The seals are designed for an environment where they are not exposed to high pressure. Submerging a bicycle hub in water or other liquid can also compromise the seals. Under normal circumstances and use, water cannot get into the hubs.
People who service their hubs use differing maintenance schedules. Their recommendations include maintenance after each tour, after replacing tires, every 400 miles, every thousand miles, etc. My opinion is that if people feel more confident in the reliability of their equipment using this approach, that is fine. I am not a believer. Modern seal designs and lubricants have inherently increased hub reliability.
Moreover, hubs can be inspected without taking them apart. I put my bicycle on a rack and rotate the wheels. I listen for sounds coming from the hubs and look for free rotation. During free rotation, a wheel will usually spin to a stop and reverse as the heavy side seeks the bottom of the rotation. On the rack I also check for side play. There should be no side play when you grasp the rim and try to move it laterally. I use both slow motions to try to feel large side play and rapid motions to try to feel slight amounts of play.
I share the opinion of some that the rims are more likely to wear out before the hubs, bottom bracket, and stem. That observation has me thinking about my rims. They are steel rims, but it is time that I measured them with a micrometer to see what remains of the material where the brake pad friction is applied. In the meantime, I am determined to continue to ride my LHT without maintenance on the sealed bearings.