This is me on my 60cm Rivendell Sam Hillborne. This is a comfortable fit. I think just about anyone, even those without a trained eye, can see that I’m in a relaxed, natural position. The position places just enough weight forward on the bars that I don’t feel planted on the saddle, but I can ride for hours with no wrist or neck pain.
The frame was sized using a “traditional” method. Essentially, it’s the largest frame I can ride in this model while still having just enough standover clearance. On paper, the 620mm effective top tube should be way too long for my build — I have long legs and a relatively short torso — but in practice it’s a good fit (compare this to my 56cm LHT’s 570mm top tube).
The $64 question is, “How is this possible?” I believe it’s a combination of this bike’s relatively shallow seat tube angle, upsloping top tube, and quill stem, as follows:
- On bikes with steep seat tube angles, many people jam their saddles all the way back, or even go as far as purchasing seat posts with extra set-back to place the saddle further behind the bottom bracket. Doing this has the effect of lengthening the top tube and slackening the seat tube angle.
- An upsloping top tube raises the front of the bike, making it easier to place the grip area of the handlebars at or above the height of the saddle.
- The height of a quill stem is easily adjusted, again, making it easier to place the grip area of the handlebars at or above the height of the saddle. Higher bars essentially nullify the greater reach of a longer top tube on a larger frame.
A bike may have a longer effective top tube length on paper, but depending upon how it’s set-up, the physical reach to the bars may be the same (or even shorter) as on a bike with a shorter top tube that’s set-up differently. In the case of my bike shown above, the 71.5 degree seat tube angle, short reach quill stem, and Moustahce handlebars make for a fit that works well for me, even with what looks like a too-long top tube on paper. To get the same fit on a smaller frame would require a longer reach stem and more stem extension above the headset. The bike would be insignificantly lighter, the steering would be affected because more of the rider’s weight would be on the front wheel (whether this is better or worse is subjective), and in my opinion, the bike would be less aesthetically appealing because more seast post and stem would be showing.
Even though I happen to be a proponent of traditional sizing methods, none of the above is to promote any one particular approach to sizing and fit. The important thing is to remember that it’s a subtle combination of frame size, frame geometry, and component selection that results in a particular rider position, and that more often than not, the numbers on a geometry spreadsheet don’t tell the whole story.