Turning the bar 90 degrees causes the head tube to drop, steepening the head tube measurement.
On Tue, Oct 6, 2009 at 5:15 PM, David Snyder <dddd@pacbell.net> wrote:
> I'm surprised that no one has suggested the "regular" mechanical
> hanging-weight dial angle finder, such as the $10, ~4X4" Craftsman.
>
> It's easily good to a half degree I'd say, enough to get in the ballpark
> with stem length or a prospective frame/bike purchase. I carry one to
> every
> bike swap.
>
> One drawback can be fitting it along the head tube, as it's more bulky than
> these tiny digital units. (and with center pulls, I have to turn the bars
> 90-degr.)
>
> I always measure with the bike on the ground, on it's wheels or inflated
> tires. I then turn the bike 180-degr and check again, correcting for
> non-level ground.
> One should also verify an on-center instrument by checking seat angle from
> the right, then left side of the bike. The 2 readings should be identical,
> or the indicator line is likely not quite square with the magnetic side of
> the
> angle finder (I checked the whole rack of instruments in the store, doing
> left/right comparisons against a shelving strut. Many were not centered
> too
> well).
>
> No batteries to replace, cheap, fast and durable. Mine's going on
> 10 years plus now.
>
> David Snyder
> Auburn, CA usa
> _______________________________________________
>
--
Ken Freeman
Ann Arbor, MI USA