deacon mark

Ok all these questions on headset I have a question on my Ti bike. It has Shimano 6800 cranks and BB. This is a standard BSA threaded BB with the usual external bearings. The bike is going to be 4 years old in March. It has about 22,000 miles on the BB. So far the cranks spins perfect and I feel as good as they did new really. I have never had an issue. I don't normally ride in the rain but we know we get caught in it at times and wet pavement. Should I pull the cranks and inspect or do anything. To me if it needed servicing due to BB wear I would just buy a new BB.

If you were me would you buy a new one and simply put it in or pull it and clean things up if needed. Really I am one to do routine maintenance and such but in this case the cranks spin like a top if I take off the chain and no play. let me know.

Eggman84

I have replaced my Shimano XT level external BB on my touring bike twice, each time at about 15,000 mile. Both times the BB started making noise, indicating all was not right. First time, the BB started to make a rhythmic grinding noise; upon removal found one bearing was rough. The 2nd time< the BB was making a rhythmic clicking noise; upon removal the bearings seemed to turn smoothly but one seemed to have a very small amount of lateral play. Considering how easy it is to remove Shimano Hollowtech II cranksets (and the BB cus) you can easily check the bearings with the crank removed. If they run smoothly and there is no noise then no reason to change. The stock Shimano BBs are not very expensive so if in doubt, buy a spare to have on hand. There are way more expensive BBs than the Shimano ones, but not sure if the cot justifies the minor increase in efficiency.

Unca_Sam

It's been said here before many times by dsbrantjr : Never fix a working piece!

Unless you have an indication of a problem like play after correct preload or unusual noise or increased friction leave it alone until you do. The bearings are sealed units, and there's nothing you can do but replace them anyway. If you're careful, you can take the crank out and gently clean any accumulated grime out from around the external bearings, but I wouldn't take those off unless I'm replacing them.

I pulled my Hollowtech II crank once because the chainrings and DS crank were caked with grime. I ended up having to buy a new pinch bolt for the NDS crank arm because the head had stripped and wouldn't support the full recommended torque before the driver cammed out. You also need to be aware of that safety clip on the NDS, and not damage it.

Iride01 

Depends on you and what makes you feel like you. I can't think of any of my bikes that taking it apart and cleaning, greasing, adjusting or anything else ever made much of any difference other than I got a little better in my skill and knowledge. But nothing that I may have prevented would have been much if any more costly to deal with it I'd done nothing and waited for a problem to show itself.

In my youth I used to take my bike completely apart several times a year and completely rebuild it. Today, other than lubing the chain regularly, I pretty much wait for something to happen. If your crank or bb starts making a noise or you start feeling a bump or grind in the bearing, it's not going to be much different in the actions and money you spend when it happens as opposed to the potentially more money you'll spend trying to prevent it.

HillRider

For sealed units like Shimano HTII bottom brackets, "if it ain't broke, don't fix it" is my approach too. I have two HTII cranks with BB-6700 bottom brackets and each has over 25,000 miles. They are running perfectly and won't be touched until there is a clear indication something is wrong. I have pulled the cranks from both a couple of times to clean the chainrings and spindles but the bb cups have never been removes since they were new. I did install them (BS threaded) with plenty of grease and torqued them to spec so I'm not worried they will corrode into place either.

Geepig

If anyone enjoys taking things apart and rebuilding them then I find racing and renovating clunkers both offer copious opportunity. I am midway thru rebuilding half a dozen BBs for the latter reason, and it is heaven

andrewclaus

I once prophylactically replaced a sealed cartridge BB with over 20K miles on it before leaving on a 5K mile tour. Normally I wouldn't do that.

Iride01 

And that is a good reason to do so. I also do consider what the current state of "mechanical well being" is for my bike. However almost all my riding is nothing so important that if interrupted by a maintenance problem that it'll set me back in even the slightest of ways. The closest I come is if my tires are wearing thin prior to an organized Century ride then I'll change them.

If I was to ever plan a big tour like you must have done, I'd be more in the preventative maintenance mode of thinking than the wait till it's a problem mindset.

datlas 

Buy a new BB and keep it on the shelf for when you need it. Leave this one alone. It likely will need to be replaced in the next 0-3 years based on my (limited) experience.

ARider2

One benefit to taking everything apart, especially on a bike that sees a lot of use in wet conditions, is to prevent parts from seizing in place due to corrosion. Once apart everything can be cleaned and fresh grease applied which will prevent parts from seizing. Another benefit is to isolate the bearings for testing. If testing with the crank still together, one can spin the crank, or apply pressure from side to check for side play, but when taken apart one can get a better idea of the condition of external bearings by simply spinning them. It depends on whether you are the type to perform preventative maintenance, or if you are the type to wait for a problem to arise before performing a repair. I just took out a cartridge style BB on a road bike that is over 20 years where testing did not reveal any problems but it gave me a chance to check the BB itself as well as to clean and grease the BB shell and threads before putting everything back together. No problems were found but I figure whenever the BB needs to be pulled it will be easier in the future.

HillRider

I did just that. When I first got the cranks, I bought two spare HTII bottom brackets assuming I would need them in the foreseeable future. Five years and 25,000 miles on each existing one, I'm still waiting to use the replacements.

One thing having spares does is keeps you from being a victim of designed obsolescence. It was entirely possible that HTII would have been replaced by something completely incompatible before the cranks wore out.