Is a BB spindle sleeve required? So yesterday I washed my bike which is a Stock Components Surly Straggler 2015. I noted some squeaking around the BB even after lubing the chain so I decided to clean the bottom bracket. I didn't have the tools so I went out to buy them, and funnily, when I came back 2 hours later the squeak was gone. So it must have been related to water somehow. Anyhow, I now had the tools so I wanted to use them.. I removed the left crank and then the spindle. I noted then that the BB only has the two cups, but there's no sleeve, this center plastic tube through which the spindle runs:



I wonder why my bike is missing that piece? Is it not absolutely required?

EDIT: I found the Surly bottom bracket installation instructions here and from this PDF it seems like for my 68mm bracket, no sleeve is provided:

 

So I guess that the part isn't 'missing', and the mention of 'Road' use in the table could suggest that they assume you don't hit any dirt. The frame does have a small drain hole in the bracket. Well, but I DO hit the dirt. Can anyone suggest a BB upgrade? It somehow seems logical that a sleeve will protect better.
It's not required for the BB to function or the bearings to be located correctly or loaded correctly. It is only a shield against contamination, particularly from water that gets into the seattube at the seatpost opening. That said they're actually pretty important parts that do a lot to make the life of the BB what it should be.

I have no idea why yours might be missing. My guess would be a mistake when assembling or servicing the bike. Make sure it's not still in the BB shell. They pop on and off the cups easily so it could have gotten stuck in their. Sometimes you have to loosen the BB cable guide mounting screw for the BB sleeve to pass through.