For those here that are new to vintage bike restoration or just for you that don't know:
Aluminum and steel really like to be close to each other, so much that they start exchanging electrons and other stuff that is hard to understand as a bicycle mechanic / enthusiast.
In other words: THEY GET STUCK, if you have ever tried to get a aluminum seat post out of a steel frame ; U know how bad it can get.
please don't put aluminum seat posts in steel frames and also don't use aluminum retainers (cup holders?) for your bottom bracket in a steel frame..
watch this video or look up Galvanic corrosion if you're interested how it works.
by P24productions