John,
You should always use some sort of anti-sieze on aluminum-to-anything-else contact areas (even aluminum-to-aluminum) to keep down oxidation. Aluminum will eagerly react to other metals, and aluminum oxide is really hard stuff (think sandpaper.) Some greases work ok, but grease is really designed for bearings (i.e. moving parts.) It has to be replaced fairly often, especial ly on a "working" bike, or it will break down over time. That is what cause s unremovable stems.
Real anti-sieze is best. It is designed for non-moving contact points. It u sually has metallic additives suspended in petroleum components, and works better and lasts a lot longer than grease.
I haven't heard of using silicone, but like paint, it would add unwelcome t hickness to tight tolerance fits. Both would also certainly interfere with the friction fit between stem and steerer. Neither would likely withstand t he compression such a fit requires, and would either crack in the case of p aint, or just get squeezed out of the way at the highest pressure points in the case of silicone.
Strength is another, and more important issue to consider when using alumin um hardware. If possible, I always tighten the part to recommended torque w ith a steel bolt or nut first to make sure it's secure, then remove it and install the aluminum fastener. Otherwise, it's easy to overstress and strip the threads, or conversely, not get it tight enough.
Greg Reiche CyclArt Vista, CA USA
-----Original Message----- From: classicrendezvous-bounces@bikelist.org [mailto:classicrendezvous-bounces@bikelist.org]On Behalf Of John Hurley Sent: Monday, January 05, 2009 10:52 AM To: classicrendezvous@bikelist.org Subject: [CR]Alloy stem bolts
Does anyone have any advice on using an aluminum bolt to attach stem to fork steering tube? I've read various horror stories about inextricable stems, even when using steel bolts. Would it be advisable to use paint or silicone grease or something else to prevent the wedge and threads from bonding? John Hurley Austin, Texas, USA
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