Re: Stem tightening, was Re: [CR]The Zen of 7 mm Hex Key stems


Example: Framebuilders:Dario Pegoretti

Date: Wed, 04 Jan 2006 00:31:29 -0500
From: Dave Salovesh <darsal@mindspring.com>
To: classicrendezvous@bikelist.org
Subject: Re: Stem tightening, was Re: [CR]The Zen of 7 mm Hex Key stems
References: <43BB1099.3060000@cox.net>
In-Reply-To: <43BB1099.3060000@cox.net>


Harvey M Sachs wrote:
> I've always felt that stems should be just tight enough to not turn in
> the steerer under emergency conditions -- and no tighter. I've always
> tried to set things up so the stem would be loose enough to give while
> crashing, since that might lessen injury.

That's what we learned from our career head mech back in Chicago. I never quite knew what he did before the shop where I worked, but he did it as one of the last Schwinn Chicago employees. Chances are it had history before it got to us.
> Am I overanalyzing the situation? Does the rest of the world just
> clamp on down till it is real tight (the way I do at the other end of
> the stem, so the bars don't rotate when I stand and apply the Mighty
> Thrust of the 61 year old body)?

Both ends, I thought - if one could get you, the other could too.

The only problem I've had with the concept is knowing what "but no tighter" is supposed to mean. If something gives without a crash it clearly wasn't tight enough, but I'm not sure how you state the inverse - if something doesn't give in a crash, was the clamp too tight or the crash too light?

I've been blessedly crash-free for going on 20 years of adult road riding (only 2 where I didn't - or couldn't - dust myself off and keep rolling) so I'm a pretty bad sample for this. But in those few experiences, I've been quite surprised at the forces that apparently came into play, judging from the aftermath. I have a hunch that for every degree of "tight enough" there's a crash out there that will shift it. The trick is to guess how hard you want to crash, and make it all no tighter than that.

I just haven't found that setting on my torque wrenches.

Dave Salovesh
Washington DC