I'd say these numbers do compute, that is, I can compute a trail value for this bike, but I don't like the answer. If it is 76 degrees and 40 mm and I assume a 337 mm radius, the trail is 43 mm, definitely a low value. For Jan's racing Marinoni, it's 55 mm. A study of the [off-topic] modern racing bikes as might be used in recent TDFs shows trails around 60 mm.
This Peugeot shows a geometric trail way below the range of some more modern racers. I would recommend re-measuring the frame numbers being as careful as possible: level the top tube, or at least correct the head tube angle for the angle of the top tube, and either measure trail directly on a piece of paper sitting under the bike, or get a helper (bike buddy works well, cat works less well) to hold a straightedge in place while you measure the perpendicular distance to the front axle.
I also agree with Jan, with such a steep head tube I'd expect a really long top tube. The front center should tell if the frame "makes sense."
Will measuring cure the toe overlap? Alas, no.
Ken Freeman
Ann Arbor, MI USA
> At 9:06 PM -0800 10/31/06, jj and kk wrote:
\r?\n>
\r?\n> >An angle measure of the head tube read 76 degrees. fork rake I would
\r?\n> >guess was 40mm.
\r?\n> >With reference to the recent toe clip overlap thread, this one JUST
\r?\n> >missed interference.
\r?\n>
\r?\n> Unless the frame has a _very_ long top tube or the rider uses _very_
\r?\n> short toeclips, there is no way these numbers compute. In my size
\r?\n> (57-58 cm top tube), bikes with a 73 degree head angle and 40 mm fork
\r?\n> offset (rake) usually still have toeclip overlap.
\r?\n>
\r?\n> If your angle finder did not read correctly (or the bike wasn't on
\r?\n> level ground), then perhaps your angles are off. If your rider used M
\r?\n> size toeclips, then this could be a bike with a 73-74 degree head and
\r?\n> 40-45 mm offset. That isn't far off a traditional racing bike
\r?\n> geometry. It will feel great at high speed (>20 mph), but at lower
\r?\n> speeds, it may feel twitchy to the uninitiated. My Marinoni's
\r?\n> measurements are 74 degrees and 40 mm, if I recall correctly. A
\r?\n> great-handling bike at racing speeds, but not much fun at 13-15 mph.
\r?\n>
\r?\n> Do you happen to have a front-center measurement? That would allow
\r?\n> double-checking the angle measurements.
\r?\n> --
\r?\n> Jan Heine
\r?\n> Editor
\r?\n> Bicycle Quarterly
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