Recently I sold a frameset to a Bay Area resident. He's also a member of an on-line bicycle related group. After he picked up the frame and set about building it, he sent me the link of this review of the frame. The summary of his first ride report was summed up with these two words: "Pure win." Works for me and thank you!
Further down the comment list to this post, there were comments about frame sizing and wishing I would have made frames in 2cm increments instead of 3cm. I would have preferred to do that as well, but I couldn't afford to have produced that many frames and stock that many sizes, initially. I may make some changes in the future. It is wise to start off small and modestly.
Regarding the sizing and how frames are sized, it's all over the board and I do agree there should be some consistency. There is, however, consistency in the main dimension that I am most interested in how a bike fits me: top tube length. Effective top tube length, that is, since most frames these days have sloping top tubes. Back when all frames had horizontal top tubes, frame sizing was center-to-top or center-to-center. That's center to the top of the top tube or center to the center of the top tube. However, as soon as top tubes started sloping, there was no one consistent angle to the sloping top tube and frame size numbers started receding.
During this time of shortening seat tubes, I still rode a frame with a top tube length at least 60cm long. I personally don't mind if my frame has a horizontal or sloping top tube - as long as my three contact points (seat, bottom bracket, handlebar) are where I need them. Well, where I need them without going to extreme measures to get them there. On a road bike, I'll use between a 12cm and 14cm stem and usually a 300-350mm length seat post with an inch of offset.
Even though the standard size determination on frames through the horizontal top tube years was the c-t dimension (center to top of top tube), when I created a complete line of frames that featured sloping top tubes for Masi years ago, I kept the c-t size designation by designing the frames based around a theoretical horizontal top tube, even though the top tube sloped and the actual size was smaller. It made sense to me.
Now that I have my own frames, I called out the sizes based to the actual length of the seat tube, center-to-top of seat tube. The top tubes have about a 2 degree slope to them so the traditional center-to-top of top tube dimension yields a smaller frame. On all the frames, there is 25mm of seat tube extending above the top tube. So, if you want a c-t dimension, subtract 2.5cm from my frame size. I ride the 62. The c-t dimension would be 59.5. However, saying that it's a 59 (rounding down) gives a false impression of the actual size of the bike when it's not taken along with the top tube length (605 in this case). It's my decision. I try to make sure it's clear by spelling out that the size is the length of the seat tube.
Recently, some folks have tried to create a new method of sizing a frame: Stack and Reach. This system cares not if your top tube slopes. If you know your ideal stack and reach, then it's simply a matter of picking the frame size based on the closest stack and reach to your bike fit. I've thought about including stack and reach in my geometry chart and may add it at some point, but definitely will include it with any new frames I bring to market.
While pondering this post, I composed a little visual based on three frame drawings of what is, essentially, the same frame size. The only difference is the length of the seat tube and therefore what the size of the frame may be considered. Even with fairly significant changes in the frame "size" (seat tube length), the Stack and Reach remain exactly the same.
This drawing shows a frame with a horizontal top tube and a seat tube of 60cm center-to-center. Stack is 603.3mm, reach is 415.1mm.
This frame is sporting a 2 degree sloping top tube (like my frames). Seat tube is now 580cm. Stack and reach remain unchanged.
This next one has a more dramatic slope to the top tube. Seat tube of what was a 60cm c-c frame is now down to 54cm and the actual top tube length has been reduced by 16mm. Stack and reach are unchanged.
What I'm seeing when I see these images are dramatically shortened tubes. Lopping 16mm off a top tube and 60mm off a seat tube can result in some decent weight savings. Hmmmm...not that I'm a weight weenie, but ...