I have an older model Giant Nutra bike. I have been riding it for years and never had the wheel bearing serviced. Do you need to have the wheel bearings serviced and if so how often. They are sealed bearing so I am not sure how you would service them. The bike seems to roll fine but it just seems that after awhile you would need to have the bearings serviced or greased at some point.

YES!! they do need at least re-greased once in a while. Grease dries out to a gummy state then
the bearings get ground to dust. Fresh grease will make the bike roll almost by itself!

On a bike used everyday once every two years is good if not ridden in the wet. If wet once a year.
For lesser riding times about once every 3 years is good. (remember that grease drys out)

Get'um re-greased and maybe you'll get lucky and not need new bearings..but I doubt it.

Hmm....replacing the bearings sounds like an expensive proposition and since my bike is OLD I figure the bearings must be worn.....sigh...any idea how much that will cost?

Depends.

Just what do you mean by "sealed bearings"? There's "cartridge bearings" and there's "sealed mechanism".

Cartridge bearings are pressed into the hub shell and the axle is pressed through the bearing. Generally they take no maintenance and, when they die, you press the old bearing out of the hub shell and press in another.

Most modern bicycle hubs today have sealed mechanisms. It's a conventional cup and cone bearing with some kind of wiper seal or labyrinth system to keep the grease in and the water out. These hubs are easily user servicable and probably should be cleaned and regreased every 5,000 miles or so. A shop would probably charge you $15.00 to $25.00 per wheel to overhaul a sealed mechanism hub.

In the days that preceeded sealed mechanisms, one good rain ride was pretty much all that it took to make your hubs cry for new grease.

It depends if you have the "seal mechanism" bearings. The seal just makes it harder for water to get at the bearings. You just need to go to the LBS and get some ball bearings of the right side, take out the old bearings, replace with the new, clean the grease out, put in new grease. With grease and bearings, you are talking less than $10 (or so I think).

If they are cartridge bearings, you can buy the cartridges and replace them. I don't know what they charge for cartridges these days.

The thing about cartridges is they tend to last a long time. You just wait until they run rough.

With loose bearings, waiting too long can wear the races and cones which is not good. So you need to do it every 5000 miles or so.

Ok I know nothing about wheel bearings. How do I tell what type I have? My bike is a Giant Nutra which is an older model hybrid I believe they call it.

On a Hybrid it would be most likely that you have a sealing mechanism, cartridge type wheel bearings are usually found on high end wheels. Overhauling wheel bearings isn't hard, it just takes some experience to get it adjusted "just right", not too tight, or not to loose. It is done by feel. See if a LBS near you offers some type of repair of maintenance class, like the Park Tool School.
I do mine once a year, or if I notice a problem, like grinding of looseness.

see www.parktools.com
You can do it yourself, you will need to buy tools, grease bearings, or take it to your LBS. There may be a bike club, coop, or advocacy group that has maintenance night events.

You may also need new 'cones'.

I know I could do the work myself with a little guidance. It's like anything else the first time is the hardest. I watched a video on YouTube and it looks pretty easy to do mechanically. The only drawback is purchasing the tools is more expensive than having someone do it for me. Then there is the issue of parts that I have no idea what I need or sizes and part numbers. I am sure if someone showed me the procedure I could do it nevertheless.

Performance Cycling said they would do it for $20 an axle so it is worth it to me to have it done right the first time. Thanks for the suggestion however.....

cone wrench

It's a really easy DIY project. the hardest part is making sure you don't get the cones too tight or too loose when you reassemble. all you really need is some good bearing grease, a cone wrench and an adjustable wrench, but a vise with soft jaws (wood or copper) to hold the axle while you loosen and tighten the lock nut also helps.

google is your friend:
https://www.google.com/search?client=...UTF-8&oe=UTF-8

I'm pretty sure that I'm in the minority here but I have a 1990 Trek 790 hybrid (top of the line at the time) with Shimano Deore DX hubs. I've ridden well over 30,000 miles on them and finally opened up the front one this year during a repair course. The grease looked fine and everything ran smooth. We didn't need to take the bearings out and repack anything at all.

Some other bikes' bearings were pitted and others were slightly oval. Rolling them on a table you could see them wobble and head off in anything other than a straight line.

In any case, it's an easy enough job to do...just go slow.

In the "old" days, wheel bearings were very easy to service, and most shops suggested an annual re-greasing and adjustment. Today, many bearings are not easy to service, and doing the job right will cost more than many people want to spend.

As a result, for folks who have a wheel worth less than $200, and the bike shop is asking $50 to regrease the bearings, it is tempting to simply ride that wheel until it has obvious problems.

I have a pair of touring wheels from 1984 that have never been greased. The shop says they have "odd" seals and impossible to replace sealed bearings...they don't want to fool with the wheels. After 25 years of moderate use, the wheels still run smooth enough, so why mess with them?

Once you have made the investment in cone wrenches, rebuilding most hubs is pretty easy; it's a matter of developing an educated feel for the exact adjustment.
I maintain our fleet of police bikes (17 of 'em) and my own as well, and also rebuild/refurbish old bikes for resale. So, I do a lot of hub rebuilding.
For me, the necessary tools and the practice are well worth the investment.

However, for the owner of one bike who might do this once in a blue moon...Might be better to take it to the shop.
One thing; you cannot check the bearings while the wheels are still on the bike. Too much mechanical advantage from the wheel.
You have to pop them off and turn the axle with your fingers. You'll know right away, if it feels like someone poured sand in there; they need rebuilding. If they feel slick with no side-to-side play, you're good.

Would regreasing the bearings be part of replacing a spoke on the drive side of a wheel for a mountain bike? I watched the video on bearings, and it looked like they might have needed to take out the bearings when they changed spokes - I had a spoke replaced last month and didn't get to watch when they did the work. The wheels about 3 years old, and now I'm wondering if I need to do this or if they would have done it when the spoke was replaced. Also, would automotive wheel bearing grease work for bicycle? It seems like the automotive grease would be made to higher standards than a bicycle would require.

No, spokes are entirely seperate. You might need to pull the cogset in order to remove the broken-off part on some bikes, likely they just used a "clean" wheel to show more clearly how to do it.

Unless theywere really bad, overhauling wheel bearings would not be a necessary part of a spoke replacement job.

Automotive wheel bearing grease would be way too heavy to be a good choice for bicycle wheel use.

It's interesting. I redid the bearings on my ford pick-up. In the few years since, I have done 30 000 miles. It was just a dab of grease worked into a new cagged bearings, and so far, so good. On the other hand on my touring bike, I did 1000 miles on new LX wheels with rubber boots on the hubs. several days of that riding was in rain on roads, not off road with river crossing or junk like that. The grease was contaminated when I pulled the axles, and while I though I was being precious about the maintenance it needed it badly.

I`we got cartridge type wheel bearings in some old wheels with drum brakes. Bomb proof, runs soo smooth. I`we been wondering what it looks like innside (guess they are from the late 70, early 80`s). I`we been thinking only maintenance would be replacing the whole thing, almost like in a sealed BB cartridge.

Park has already typed all the stuff out that you need and how to do it. The rear hub bearings should be 1/4" and the front 3/16". If you have to replace cones, you'll need to go the your LBS. Shimano has done some hinky things in the past and not all cones for their hubs are the same.