[Classicrendezvous] Friction, was oil ports on hubs


Example: Production Builders:Cinelli

Date: Wed, 04 Oct 2000 18:27:12 -0400
To: tomwitkop@juno.com, classicrendezvous@bikelist.org
From: Harvey M Sachs <sachs@erols.com>
In-Reply-To: <20001004.175853.-1950525.2.tomwitkop@juno.com>
Subject: [Classicrendezvous] Friction, was oil ports on hubs

At 05:58 PM 10/4/2000 -0400, tomwitkop@juno.com wrote:
>What is the point of the oil ports in campagnolo record hubs? I have
>some stiff old dura ace hubs and am tempted to inject motor oil to loosen
>up the grease but if that is the idea, why aren't they are oil ports on
>the track hubs? It would seem that motor oil would offer less resistance
>than grease and make the hubs incrementally faster, however, the motor
>oil would also be more rapidly displaced making it more appropriate for a
>track event rather than a Road racing event.

A couple of thougts on this: 1) On the D/A hubs that are so stiff, I'd offer the following ideas: (1) Loosen the cones a smidge (1/6 turn?) and see if they free up a great deal. If so, we might have an adjustment issue. If not, I'd inject mineral spirits or the equivalent (WD 40) to loosen things a bit while you rotate the axle. Then clean the hub properly, if that loosens it up.

2) There is a lot of bearing mythology, and I don't have all the answers. The first thing is that grease = (oil) + (soap). "lithium" grease mean a soap with lithium ions, etc. My understanding is that the soap is added to build static viscosity and water repellancy. The second thing, one which is real important but which I'm ignorant about, is what actually matters in reducing friction UNDER LOAD. I'd guess that the hub oilers were put on for track use, as you surmise, with oil (I'd prefer straight oil, not motor oil with all its additives, but don't know why). But, here's the big deal: All of us can tell the difference between a "stiff" hub, like a new Phil with cartridge bearings; and a "free" hub that spins readily in the hand. Most of us are conscious that the reason that a high flange hub spins better than a low flange is just that it has a higher inertia and spins down more slowly. What hasn't been shown, because it requires a real machine, is whether the Phil has more friction under load than the "free-spinning" hub. From what I've heard, I doubt it, but can't prove it.

Ah, here's an experiment that Jim Papadopoulos showed me. Works best with a bare hub, but can be done with a wheel: a) Adjust the hub so it feels right, and lock the cones in place. Set it up just like normal. Now, spin the axle to be sure it is running free, w/o sideplay. b) Now, put in the QR skewer. Put a couple of cone spanners or whatever between the QR flats and the hub flats, and tighten the QR. I bet you will find that the hub seems "stiffer". The compression by the QR actually shortens the space between the cones, tightening the hub.... Now, how do we properly set up hubs? I've moved toward trying to be just a hair loose, and then check for side play after installing.

Too much bandwidth, but the stuff wanted to write itself.

harvey sachs
mclean va