In a message dated 3/25/03 2:15:09 PM Pacific Standard Time, heine@mindspring.com writes:
> I am assuming a custom bike with a geometry the way you want it. If
> you keep the seat tube angle and head angle constant, the length of
> the seat tube will not affect the rider's position.
>
> On a Rivendell, the top tube slopes, and the head tube is extended.
> Certainly, the sloping top tube will be shorter (measured along the
> axis of the tube) than a horizontal one will be (as the sloping one
> takes a "beeline" to the seat tube). Also, if the head angle is
> steeper than the seat angle, a top tube higher up will be longer. But
> these effect are small, and in my experience, negligible.
>
> On bikes that interest me, I check seat angle and reach: for the
> latter, I measure the distance (c-c) seatpost-handlebars, parallel to
> the ground. This takes into account the stem as well. Note that with
> higher bars, you need more reach.
>
> Finally, the reason for Rivendell spec'ing their bikes with sloping
> this and extended that is that most buyers are so used to getting
> bikes that are too small (by Rivendell standards), that they'd balk
> if they were told the "true" size of their new bikes. A modern rider
> who is used to a 54 cm "compact" frame would be hard-pressed to
> accept a 60 cm frame for their new bike. So Rivendell suggests a 56
> or 57 cm frame, and everybody is happy.
>
> I've been there. And today I am glad that my 58 cm Rivendell in fact
> really is a 61 cm frame, if you assume a (virtual) horizontal top
> tube that starts at the top of the headlug extension.
>
> That said, I prefer the looks of my 61 cm Singer. Both ride the same.
>
> For an illustration, check Vintage Bicycle Quarterly No. 3, p. 12 and
> 13. P. 12 shows my Rivendell, p. 13 a brand-new Singer (not mine,
> unfortunately). If you overlaid the photos, you'd see that saddle,
> bars and pedals are in the same spots - the Singer rider has a very
> similar body shape to mine. Only the top tubes differ. In fact, I
> would have spec'd the Singer 1 cm taller yet.
Jan's preferences are an aesthetic choice that is perfectly valid, so what follows is my opinion and in no way invalidates or contradicts Jan's choices. My original post reflects my aesthetics regarding fit, position and function. My early introduction to "real" bicycles was heavily influenced by Italian race bikes from the 50s and 60s, so forget compact frames. They aren't part of my world and this doesn't apply to them.
First: I don't like really large frames with a fistful of seat post showing. Part of this is because when I'm descending with the cranks horizontal, I like to have the top tube between my knees. I'm 6'2", buy pants with a 34" inseam and 61 ctc or 62 ctt fits me with a Campy seatpost at the limit line. I had a 64 cm Italian Masi (years ago) and sold it because it felt way too large. In that descending position, the top tube was way above my knees and I didn't like it. My personal sense of proper proportion follows, what I was told at least, is an old Italian rule-of-thumb; the amount of seatpost showing should be roughly proportional to the length of the headtube. Remember, this is for a classic "racing" fit, not a randonneur fit. I just like the way larger frames look with some seatpost showing. Small frames look great with not-so-much and look, well, not right to my eye with the post hiked all the way up.
Second: I don't care for the Nitto super tall stem because I don't trust the material. They may be fine, buy I'm a guy who likes steel bars and stems on his track bikes. I'm not any more, but I used to be strong enough that it mattered and I don't like to recommend anything I wouldn't use to someone I don't know VERY well. Hence my recommendation to have a steel stem made. For normal height stems, I have a smattering of TTT (mostly because I like the 7000 series aluminum bars), Cinelli and Ambrosio. I have plenty of handlebars by Cinelli, Fiamme etc, but ALL the other bars are made from softer alloys that bend easily and polish easily. As a result, they sag over time, just from doing miles with your hands on the hoods. If a bar or stem breaks, you may be toast. That Nitto isn't on my radar. Maybe I just don't like how it looks.
Third: I think seat angle is the primary (meaning first) priority when choosing a frame. There are lots of variables, some of which I went into awhile ago when I wrote about looking at top tubes as two dimensions, not one.
Fourth: This is again just my opinion, so no offense, I don't like the way the extended headtube thing looks. I built my track bike with one of those "clips" that threads on between the upper race and the locknut, with a bolt through it to clamp it to the steerer (I'm desperate for one if anyone has one, the piece was stolen while the bike was apart). It raises the bars about an inch, and since it's a 30s-50s part it is certainly classic in appearance.
Fifth: I like level top tubes with the exception of very small frames, where keeping it level just raises the bottom bracket.
Jan's point is excellent in that he shows that if you overlaid the two
designs of his bikes (Rivendell and Singer), you would find the same
seat/handlebar/pedal relationships. The point is the position, the bike is to
put you in it. There are a number of ways to get the bars up an inch or so, I
suggested a way to do it with a more "racing" look, because that's what I
like. If you like the randonneur look, the larger frame option is certainly a
classic look and does work.
Stevan Thomas
Alameda, CA