I am curious to know how long bearings last for certain parts, I will be putting 2000-3000km (1300-1900mi into a new bike I’m building, then taking the bike on a 5000km(3100mi) trip, whilst on the trip I won’t really have a chance to service/replace bearings.

So before I go on the big trip, what bearings should I consider replacing? (im pretty mush asking what bearings will last 7000km/4400mi)

Jockey Wheels: Shimano XT RD-T8000 rear derailleur
Bottom Bracket: Shimano BB-MT800, unknown bearing type
Front Hub: SON28 disc brake front hub, cartridge bearings
Rear Hub: Shimano XT M756A rear hub, cup and cone bearings
Pedals: Nukeproof Horizon Pro Flat Pedals, bushings & cartridge bearings
Headset: FSA Orbit MX headset, cartridge bearings

I'm running a set of wheels with cartridge bearings that I used to ride across the country in 1997. The wheels didn't get a lot of use after that until this year when I built up an old bike as a commuter. Still going strong.

I'll tell you when I wear them out. That could take a very long time, however, considering that I have two sets of Phil Wood hubs with 16,000+ and 11,000+ miles on them. They are showing no signs of needing replacement nor have they needed any kind of maintenance. I've had lots of other cartridge bearing wheels that I didn't keep such meticulous records on but I've only ever had to replace bearings in 2 wheels. They last roughly forever...and a lot longer than cup and cone bearings.

Since this is all new stuff (from your build post in Touring), I wouldn't expect any need for replacement on anything for a very long time...even the cup and cone bearings on the XT rear hub. I would suggest that you check the adjustment on the XT hub bearings before you start, however. In my experience, Shimano hubs are too tight from the factory.

No one will be able to tell you exactly how long they last, because people ride in wildly varying conditions. Like [MENTION=21724]cyccommute[/MENTION], I'm convinced enough by the longevity of cartridge bearings that I would trust anything that still spins well on tour.

From your list, would suspect if you have any issues, it will only be from the pedals, and then doubt they will be an issue

From experience, Shimano jockey wheels will go ninja star shaped before the ceramic cartridges have any wear, especially the higher end versions.

Shimano HT2 BB's are pretty sorted, there were longevity issues when they were first introduced, and you would only get a few months out of them, not had to replace any in the last few years.

For the front hub, I did about 15000km on a SON hub (rim brake model) before selling it & going disc, as far as I know it's still going strong.

The rear hub you list is a great hub, but heavy vs other XT model, cup and cone, so not really part of the question.

pedals see above

Orbit MX headset seem to be indestructible, I have one which is well over 10 years old, has been on a few bikes and is smooth as the day it was first installed.

I have a pair of:
- Phil Wood cartridge hubs (purchased in 1997) that lasted ~10 years before needing new bearings.
- Campy cartridge hubs (purchased in 2006) still on the original bearings.
- White Industries hubs (purchased in 2010) still on the original bearings.

I have no idea of how many miles on each, but I ride 4000-5000 miles/year.

It all depends on the environment's relative cleanliness and Moisture level.

Blowing Sand dunes and Stream Fording in your plans?

I would overhaul the rear hub before the tour. I overhaul mine every 2500 miles or so. They would be good for a long tour.
Radial bearings have a long life span if they don't spend a lot of time in the wet. The seals on all the bearings on a bike are dust seals and only do a marginal job of keeping water out.

azza_333, I'd look at the wheel bearings prior to the 5K km trip. Shimano hubs are slightly tight when new, but I wait for about 100 miles before checking or adjusting.

Brad

Thanks everyone for replies, I will service the rear hub before the start of my trip, and replace the pedal bearings just in case.

With an adjustable cup and cone hub there is no reason that you should wait nor any reason that the hub shouldn't be properly adjusted from the factory. You seem to be working under the idea that the hubs need some kind of "break in period" but they really don't.

I'm not sure why Shimano over tightens their hubs but it seems to be a consistent issue.

I know the only things on my bike that will need to be broken in are my brake pads, and my saddle. I was more just concerned about the bearings not lasting for the distances on the entire trip.

Honestly, neither of those things are "broken in". Bedding of brake pads and "breaking in" a saddle are really myths. If there is glazing on the pad or the rotor, applying the brakes gets rid of them in short order. If you don't do the mythic "bedding" a disc, the braking won't be bad for the life of the brakes.

As for the saddle, you don't really make any changes to the saddle, you make changes to "you". The delicate bits get used to it. I have several Brooks saddles with thousands of miles on them. They don't have "divots" nor have they changed any from the original out of the box saddle. All I did was get used to how they feel. There is a small difference that I can feel between them and the plastic saddles I have on mountain bikes but it's only a subtle difference

The story I've heard is that it makes things easier for wheelbuilding machines. Does that sound right?

With internal cam skewers, there should be a tiny bit of wiggle until the QR is fully closed.
For the weaker external cam skewers, less or no wiggle is needed.

Yeah, maybe wheel building machines like no wiggle.

As has been noted, nothing to worry about - just ride.

I would dare to say 99% of brooks owners would disagree with you on the brookes saddle, you may not notice it but I and many others sure do, during the break in process, the leather under your sit bones will soften/stretch causing divots.

It seems that after some mileage, the hubs are not as tight. I maybe looking at a break-in period incorrectly, but it seems consistent.

Brad

Right. *I* know how to use a QR just fine.

I've got 16,000 miles (about 10 years) on a Brooks Pro and about 10,000 on a Brook B1N (about 15 years) and neither one has any "divot" in it. I'm not exactly a light guy either. I didn't take any extraordinary measures to soften either saddle, however. I Proofhide them about once a year ...when I remember to do it.

I have seen the divots you talk about on other peoples' saddles but I think they are over treating their saddles in an attempt to bend the saddle to their will instead of the other way around.

I've never heard that but it could make sense. A human builder grasps the hub by the shell but I bet the machines hold them by the axle so that the hub doesn't turn. Loosening up the cones afterwards is probably one of those things that gets neglected during the final check at a shop.

I have used proofride or any other treatment on my first brooks B17, I am extremely light 66kg (145lbs), and it still formed divots after only a couple of months on commuting. Mabye for you the saddle was already the perfect shape, but for the other 9/10th of the population we are not so lucky.

The cartridge bearings used on bikes are of the same general type as those used in electric motors. In that application, their service life is equal or greater than the motor and measured in 10s of thousands of continuous duty hours at 3600 rpm.

So we might expect similar life on bikes and would actually see that if it weren't for the variables such as exposure to weather, dust, dirt, etc.

There is also a good deal of variance in quality from the multiple sources, and many (don't take this to imply all) bike companies choose to buy the cheapest bearing rather than the best.

Then there's the rest of the engineering. Bearings work best in a rigid, aligned configuration when adjusted to proper preloads. Unfortunately many applications, especially BB assemblies are not as rigid as they should be, and so flex under load and suffer shortened bearing life.

However, despite the shortcomings which cut into bearing life, most bicyclists still may expect bearings to outlast the parts they're built into.

It depends a lot on the saddle model. B17s from the last decade or two are known to be pliable and break in quickly, while the Pros and B17Ns mentioned by Stuart are more rigid and may not show much evidence of break-in for a long time, if ever.

Most of the Brooks saddles I see around here are the plain B17 model.