Ah, but center to center opens up a whole new can of worms. A 55cm center to center will be different on a frame with a 1" top tube than say a Cannondale with a mega top tube. That is why I have always measured (on my drawings) from Center of BB to the intersection of the top line of the top tube and the center line of the seat tube. That is usually, on most seat lugs, right where the edge of the top of the seat lug is on the side of the frame where most people use to measure frames. Hope I explained that clearly as it was always the only way to measure a frame consistently regardless of tube diameters.
Mike Howard Santa Fe Springs
On Wed, May 13, 2009 at 8:17 AM, Jerome & Elizabeth Moos <
jerrymoos@sbcglobal.net> wrote:
>
> The problem with this approach is that the standover height will vary if a
> different seatlug is used or if the seattube extends above the toptube.
> Fillet-brazed Schwinns were measured this way, but the seattube extended
> maybe 1 1/2" above the toptube, so they are much smaller than the stated
> size might lead one to believe. Mercians are also measured this way. I
> forgot that when I bought a KOF Mercian KOM on eBay, and wound up with a
> frame 2 cm smaller than I expected. Fortunately, many Mercians, including
> this one, have a very high BB, so the standover ended up being about right.
>
> This does bring up the point that, regardless how the frame is measured,
> one still does not know the standover height, as that will be affected by
> frame angles and even more by BB height. So the best way to know standover
> is if the seller actually measures and states it. But if one has to buy
> based on a frames size only, c-t-c size will at least remove variables like
> extended seattubes.
>
> Regards,
>
> Jerry Moos
> Big Spring, Texas, USA
>
>
> --- On Wed, 5/13/09, bobhoveyga@aol.com <bobhoveyga@aol.com> wrote:
>
> > From: bobhoveyga@aol.com <bobhoveyga@aol.com>
> > Subject: Re: [CR] Measuring Frames
> > To: classicrendezvous@bikelist.org, brianbaylis@juno.com,
> raydobbins2003@yahoo.com
> > Date: Wednesday, May 13, 2009, 9:42 AM
> > Brian writes;
> >
> > >> I had no idea there might be others who used the
> > tip of the seat lug as the measuring standard. Any idea why
> > those who choose this method prefer it? It seems center to
> > top of top tube makes sense, as does center to center. But
> > why to the tip of the seat lug? Maybe someone has an
> > explanation...
> >
> >
> > Brian, I think there might be a clue in Ray's earlier
> > message... when asked why the measure was made to the tip of
> > the seat lug, he said that Alberto replied that it was
> > "consistent."? But consistent with whom??
> > Certainly not other builders... Ray suggests that he meant
> > consistent with his dad.?
> >
> > But I suspect Alberto may have meant "consistent from
> > measurement to measurement."? After all, the tip of the
> > seat lug is a single, discreet point:? Easy to see, no way
> > to get it wrong.? But consider the C-T measure as performed
> > by various folks... builders, bike shop personnel, or
> > newbies... sure, the center of the bottom bracket is pretty
> > obvious, but where exactly is the top of the top tube?? Is
> > it at the point where the top of the top tube and the front
> > of the seat tube intersect?? Or is it the projected line of
> > the top of the top tube where it intersects the centerline
> > of the seat tube?? Or is it a vertical line, straight up
> > from the bottom bracket, as one would measure standover
> > height?? I've always measured the second way (along the
> > centerline of the seat tube), but I've seen folks
> > measure the first way (to the tube intersection at the front
> > of the seat lug) and the resulting measurement is a bit
> > different.? And though I don't know anyone who measures
> > a vertical line, I suppose it actually kinda makes sense to
> > measure frames this way because if you know the BB height,
> > you could just add the two measurements to get a standover
> > height.
> >
> > Same goes for C-C measure... you can take it at the point
> > where the tubes intersect, or project a line to the center
> > of the seat tube, or measure vertically (again, I don't
> > know anyone who actually measures vertically, but an
> > inexperienced person who is told to measure "from the
> > center of the bottom bracket to the center of the top
> > tube" might well take the shortest distance, not
> > knowing he is supposed to follow the seat tube).??
> >
> > But a measure "from the center of the bottom bracket
> > to the point of the seat lug" leaves little room for
> > misinterpretation.? So in a way, the Masi (and Confente,
> > Paramount, Woodrup, Bob Jackson and whoever else) method
> > does kinda make sense.
> >
> > Bob Hovey
> > Columbus, GA USA
> > http://bhovey.com/