Last year I installed an external Token bottom bracket set on my bike. At the time, I did not install the plastic tube with the O-rings on each end that goes between each bearing assembly. I never gave it much thought until I got caught in the rain on a recent ride. Does that plastic tube really do anything, or am I ok without it?

The tube is meant to keep crud from getting to the bearings from the inside of the BB. For most of us that prolly isn't an issue... but it will void your 2 year warranty if you don't install the tube and O-rings.

Edit:
I just read the warranty on Token's website:
Token warrants the bottom Bracket for a period of two years against mechanical failure except in the case of water ingress due to using pressure washers or riding in adverse weather conditions.

What?? Pressure washers I understand... but they only warrant their BB if you don't ride in the rain?!?

My thoughts on the water infiltration were these:

- I don't ride in the rain deliberately, so what are the chances that enough water will find its way inside my bottom bracket during the few times I actually ride in the rain to cause damage, which would mean that the waterproof marine grease I used has been washed away (that would take a lot of rain riding).

-There is nothing preventing water from entering the outside of the bottom brackets, so why protect the inside?

-Just seemed to me that the platic tube was more for mountain bikes than road bikes.

-On a road bike, the plastic tube seemed like it would just trap heat and dust.

But, am I wrong about any of this? If I get caught in the rain, am I destroying my bearings?

Many fine Road bike frames came with cut outs in the BB shell , Branding maker,
and a drain for condensation inside the tubes .

Lots of separate issues here.

First of all it isn't rare for small bits of crud to drop the the BB from within the frame. Small bits left over from the brazing or assembly process can loosen with vibration and settle to the BB (the sump of the frame) I've seen people sabotage their own frames by filing or deburring the top of the seat tube without regard to where those filings go. I always put a smear of stiff grease at the bottom of the BB shell to trap this stuff.

Then there's water, which can attack BB bearings from two sides. When riding in the rain spray from the front wheel can hit right at the gap between the moving parts and work it's way into the bearings. Typical sealed bearings aren't proof against positive pressure so it's important that you use a waterproof grease.

Water also enters through the seat tube. Spray from the rear wheel is directed right at the tubes slot, where there's enough distortion for it to weep in. Riding through a puddle on hot days creates a more complex way for water to enter. Spray hits the slot, and at the same time cools the seat tube, dropping the internal pressure and drawing water in.

That's why it's so important that bikes with sealed BBs have a weep hole at the bottom. Since you can't really stop water from entering, you have to let it out. (on older cup/cone it simply evaporates and vents between the cup and spindle) Back when I ran Campy's east coast service center, I dealt with a number of problems with corrosion on the aluminum cups. All of them were corroded from the inside outward, and none of those bikes had a weep hole. I explained the dynamic and suggested they discuss the issue with the frame builder.

Obviously this didn't enamor me to the framebuilders, but eventually more and more builders add weep holes, and the number of cases dropped.

IMO, a decent BB should be able to deal with rain without causing problems because a bicycle is after all an outdoor vehicle and rain should be expected. OTOH damage from within from rain or debris is the ownere responsibility.

The seals on the bearings are dust seals and not meant to keep out water. The tube on the inside would help in case of condensation.

That's precisely what I am worried about. Do I need that plastic tube thing on the inside of my bottom bracket to protect the bearings from water that gets inside the frame?

With all the doubt you're having, why not just install it and stop worrying. It comes with BB's, and these external BB's are SO easy to work on, so why not just install it according to it's design and instructions???

Multiple times I've been out in the rain and forgotten to drain the water when I get home. The next time I ride, while pushing my bike upright through the door I'll be pouring water out of the drain holes at the rear of my chainstays. As FBinNY said, water comes in multiple ways, and WILL get to the BB. Probably more water than you think. If it was my own bike and I'd left it off for some specific reason, I'd definitely take the 20-30 minutes to go back and install it properly.

-Jeremy

Herein lies the problem: I don't have them anymore.

That's OK. Purchase a Sram Red BB. Install the tube on your bike, and mail the bearings to me.

I think the plastic tube was there for bottom brackets with cut out in them,most modern BB shells should be fine.

Did the old bottom brackets with cut outs use the external bearings like these?

I need to install an external BB at the weekend.

How much grease do I need to put in the BB? Pack it full, or just a smear on the ends?

TIA

Check the directions.

https://techdocs.shimano.com/media/te...9830614887.pdf

just states

Sorry to be so dimm but doesn't clearly state where to grease.

If I rememeber correctly, they come pre-greased. If they do, then let them be. Its almost impossible to pack grease into bearings without getting trace amounts of dirt in the bearings which does a lot more harm than the extra grease does good. I put a good amount of water proof marine grease on the crank spindle that goes through the bottom bracket.

Funny but Shimano doesn't mention anything about the plastic sleeve in the instructions, guess it is already around the spindle in the package. So the only place to apply grease then would be to the inner shell of the BB.

When my LBS installed my Hollowtech II for me they chose not to include the spacers and so crushed the plastic sleeve when tightening everything together. I immediately knew something was wrong because the cranks would not spin freely. Smoothed out the sleeve, reinstalled everything myself with the spacers, cranks were fine. But after only a little over 5000 miles, some contamination must have infiltrated, despite the plastic sleeve, because my cranks are now clicking. Fortunately a new Deore BB was only $20, when it gets here I'll look to see if the instructions are any more specific.

I grease the threads on the bearing cups, the shaft where it contacts the bearings and the threads of the bolts that clamp the NDS crank arm on. The bearings themselves come greased and are technically not serviceable but by carefully popping the plastic cap off the bearings they can be cleaned and relubed.

I think those sleeves mostly help keep things like rust (on steel frames) from dropping down into the BB bearings, on simple older models that weren't sealed. I think they're worth using for that purpose. For just keeping water out? Yeah, they don't work

Got my new Deore Hollowtech II in the mail today. Came with the plastic sleeve firmly attached to crank side bearing assembly, all threads were generously pre greased. Smooth!