The analogy is perfect - although for a slightly different reason. The arm is not likely to crack, but rather the softer aluminium will compress to the point of deformation and the taper will become too large. There is no need to ever grease a cotterless taper, I've met others who disagree, and upon inspection of bikes with grease on the tapers the taper is often compromised. Mike Kone in Boulder CO
At 03:58 PM 8/4/02 -0700, Greg & Darlene Pitman wrote:
>This is what I would have thought the ultimate answer would be.
>
>I no longer work on bikes. But as a pipefitter, I work on large
>mechanical equipment. One of the items I deal with is sheaves (pulleys).
>Big ones. On 2" plus shafts. These are mounted on tapered sleeves with
>collars on the outside secured by several bolts. The parts come
>liberally oiled to prevent corrosion. The instructions clearly state
>that the oil should be completely cleaned before installing in a dry
>state. As an apprentice, I once disregarded these instructions. I was
>astounded to see the central spider of a massive steel pulley crack like
>it was made of rock candy, at less than the specified torque rating.
>Needless to say, I never made this mistake again.
>
>I know these are not Campagnolo crank arms. But the mechanical concept
>seems to me to be the same. The lubrication encourages the part to slide
>too far on to the taper, overstressing it.
>
>I've been reluctant to express my opinion on this subject, for fear of
>being accused of comparing apples and oranges. So if you think I'm full
>of crap, be gentle.
>
>Greg Pitman
>Rancho Cucamonga, CA ( where riding the rollers after work these days
>means covering the bike to protect it from the steady stream of sweat
>running off my chin)