So, I got my first external bottom bracket crankset recently and at 2800 miles it started to groan. Took it to the LBS and they told me the BB cups needed replaced and that 2500 miles was not unusual. Wow.

So is this common? How long do your's last?

Ultegra SL about 3500 to 4000 before I needed to replace.

Replace the bottom bracket or replace the sealed bearing units? Those mileages sound really really low to me for something like that failing. Were they correctly installed?

They sound very low to me too. I'm used to cartridge bbs from Shimano and Campy lasting 25,000+ miles in both square taper and even Octalink form. I don't see why external bearings, if decently sealed, would fail that much sooner.

13,000 + so far on my Record UT with no signs of problems.

I suspect BB shell is off on my bike. Id like to follow the threads and reface to confirm, but am lazy I guess.

megaexo/gigapipe, far less than shimano.
shimano external has good seals, but if you ride off-road a lot, they won't last as long as cartridges which are fully sealed.
mega exo/gigapipe have really crappy seals.

One quick check on the quality of the bb threads and facing is to install the crank with the cups in place and see if the spindle slips smoothly through both bearings with no binding or alignment problems. If it does, the facing is pretty good. If it binds at all, have the bb shell faced.

Said it was the cups, not the bearings. Fulcrum. Original install was there on a new frame as part of a build up. My impression is that they are an experienced group.

Many bottom brackets come as a cups/bearings set... and the cups don't wear out the bearings do.

If the bottom bracket does not have perfectly parallel faces then you will shorten the life of the bearings. Many 'experienced' people do not realize this and claim that external bbs are always tight when new and need to break in... well often the tightness is caused by misalignment and the 'break-in' is actually the beginning of the bearings wearing out.

Have your bottom bracket faced.

I think the Fulcrum system is the same as Campy where it integrates both the spindle and bearings into the arms. The cups are installed without bearings.

The crank has always rotated without noticeable drag and after new cups were installed, does so now. The groaning seems to come on all at once and only when mashing on steep climbs. There is one more thing; I had a spill about 1000 miles ago that involved a strike to the left pedal. After the wreck, the crank had a spot where it would drag. I theorized that the arm might be a little tweaked at the spindle and gave it a firm pull. It seemed to rotate smoothly again. I really could not "see" any difference. I mentioned this to the shop, but they didn't "see" a problem there. Maybe my crank/spindle is hosed and that's the culprit?

I guess I forgot to "knock on wood" after posting to this thread. My Record Ultra-torque non-drive side bearings failed at 14,139 miles. I cleaned and lubed them once during their life. New bearings are in the mail, perhaps I will lube the new ones more frequently.

I'll assume this is a road based poll. Mountain biking these would be pretty high mileage expectations unless you never ride in adverse conditions or ride water crossings etc. Odd expression for the shop to say the cups were worn out since they don't have cups that wear out and the bearings can be replaced and even serviced if not too far gone; you can wear out the splines taking them on and off if you don't use a good tool, though. I usually open up the seals on my external bearings and clean/regrease at least once a year or simply replace the cartridge bearings (trying some Phil cartridges on one of my cranksets now). With a little preventative maintenance they'll last quite a while. Worst part about the Shimanos are their pesky plastic bearing shim/shield thingies. Nice alternative bearings can be found at enduroforkseals.com, too.

many thousand of kilometers have past in harsh condition over my dura-ace, 21years later (present day) it still works, and no strange noises.
On a russian xb3 made in 1963, it still works (that thing is built to last, at the expense of the weight, it's over-dimensioned)
On a fixed Peugeot, the BB is still original (1973)

Conclusion: BB are very durable on road bikes.

dont bother, 14k miles out of a set of replaceable bb bearings is pretty good mileage.

these are the ceramic bearings or no?

Cripes, how do you do that? I see about 500 miles before bearing failure.

No, they were the stock steel bearings and I'm replacing them with stock, although I considered ceramic from a manufacturer who claims that the Campagnolo bearings are too small. The bearings are much smaller than those in my Nuovo Record cup and spindle BB which I haven't replaced in the 40 years I've owned the bike.

Closing in on 14k miles on my DA set. Still quiet and smooth.

I've never tried this but do megaexo cranks fit in a hollowtech 2 BB?

My bike came with an FSA SL-K crankset and Ultegra cups so would assume the Megaexo would fit as well.

The Shimano cups can be cleaned and lubed. Carefully pop off the plastic cover, clean out the old grease, pump in new grease and snap on the cover.

Not sure if serious.