Bicycle Mechanics - Teflon tape vs grease.

When dealing with bottom brackets, I've always used grease. I caught an archived thread that talked about this and some users debated which was the better one to use. I figured I'd ask here due to the fact I have a new frame coming and I'll be rebuilding my bike to be set up on this frame. What do you guys think? Shall I grab some teflon tape for the BB installation on the new frame, or does grease do the same trick?

Dumb question - is teflon tape what's often referred to as, plumber's tape?

Plumbers tape is teflon tape. That's the most help I can give man.

Plumbers tape is teflon tape. That's the most help I can give man.

LOL thanks. That's a helluva first post. But hey - welcome to the forums!

Yes, the white tape that you coil around the male end of a pipe fitting or nipple before screwing it in is teflon tape (you can buy it as liquid and brush it on as well). You can also get liquid "anti-seize" that will prevent bolts/nuts from seizing together over time.

FWIW, "Plumbers tape" also refers to a metal strapping material drilled with lots of holes. It's used to hold pipes up or stabalize them (you wrap it around the pipe and then you can nail/screw through one of the holes). Looks like this:

https://www.plumbersstock.com/images/products/default/00290304.jpg

Greasing the threads will avoid corrosion that will jam a BB in place by jamming the threads. Teflon tape will not do that. Corrosion, be it simple rusting or steel to aluminium galvanic corrosion of the aluminium will still take place with teflon tape in place while grease will avoid this from happneing.

The reason teflon tape works with plumbing joints is because plumbing threads are tapered. This wedges the threads together as they are tightened and extrudes the teflong tape into any voids in the threading and ensured a gas tight joint.

But bicycle threads are all parallel so the tape will never totally seal the joint. So moisture and oxygen can still get at the metal and rust or galvanic corrosion can still take place with teflon.

We always use both. Grease goes on the BB shell threads and teflon tape on the bearing cup threads. Works great.

But bicycle threads are all parallel so the tape will never totally seal the joint. So moisture and oxygen can still get at the metal and rust or galvanic corrosion can still take place with teflon.
Theoretically you may be correct but in a practical sense two layers of teflon tape on bottom bracket cups does indeed form a hermetically sealed impervious joint. I've used it on Ti, Al and steel frames with steel and Al bottom bracket cups and there has never been the slightest sign of corrosion when disassembled a year or two later. That's even true of my steel frame "rain bike" which is exposed to bad weather, wet road and road salt on a routine basis.

Thanks Hillrider, that's good to know and stick in the mental toolbox.