[Barnlek]

I'm looking at to start working on my own bikes I'm wondering how often should I have my bottom bracket service

[HillDancer]

For vintage style caged bearings depends on mileage and environment. If the bike is a new acquisition its a good idea to service the bearings to establish a base line and ensure the bearing balls and races are healthy, plus set optimum pre-load. I do my vintage bike about once a year, primarily because bearing pre-load increases on this BB during use, not so much due to contamination or lube loss; this bike never sees rain, I don't wet it when cleaning, and it is rarely used on unpaved roads. If I were to ride in the rain or use a water hose to wash it, I would shorten the service interval.

I service (re-lube) my UT external cup Campy crank bearings around 1500 miles. The interval on this bike represents around 50 miles of rain riding, and 200 miles of un-paved road, in addition to clean & dry conditions.

Sealed bearing BBs can go a long time without service; some BB types with inaccessible bearings are non-serviceable.

[DELTUFFO]

Take it apart whether it needs it or not.

Buy your tools at the bike shop.

[Barnlek]

Originally Posted by DELTUFFO

Take it apart whether it needs it or not.

Buy your tools at the bike shop.

I just got my BB off today.
There was water in there.
So it is a very good Idea to take your bottom bracket apart whether it needs it or not to make sure there's no water in there.

[MNRider]

I agree that if you have a vintage bike with cup and ball bearings, you should service them as soon as you can just to make sure they are in good condition and properly greased. After that, How often should I service my BB? is like asking, How often should I buy new shoes?. The answer is: Whenever you need to. It will vary greatly depending on the miles you put in and under what conditions. Annually is common but you may need to do it more or less frequently. IMHO it is better to err on the side of caution and service early as long as you don't get obsessive about it.