Frame Sizing

[jimmitch]

A friend has a problem. His torso/arms are disproportionally smaller than his legs. His lower body measurements suggest he ride a 61cm frame, but his upper body measurements indicate at 56cm frame. He's been riding a 56cm Cervelo for a couple of years with an extremely long seat post (saddle height around 83cm), but it's recently been making some terrible creaking noises that are making him nervous.

A custom frame is not an option, so here's the question: if he has to buy a frame with "standard" geometry, should he opt for best fit with top tube or seat tube? If he goes with a larger frame, how will the short stem affect the handling he's gotten used to? Other than creaking, what are the disadvantages of a long seat post if he fits well in the "rider compartment"?

This bike would be used for road racing.

I'd appreciate any thoughts.

[oldbobcat]

A friend has a problem. His torso/arms are disproportionally smaller than his legs. His lower body measurements suggest he ride a 61cm frame, but his upper body measurements indicate at 56cm frame.
Any stock frame is going to be a compromise, so the trick is to find the best one. I have similar issues except for the arms. Legs say 60 or 61 but the upper body wants a 57cm top tube. My "modern" ride is virtually square 58 with an 11cm stem on spacers. My drop from saddle to bar height is rather steep, at 10 cm, but my long arms can handle it. Your buddy might be able to ride a standard 58 with a flipped stem.

"Relaxed geometry" bikes have slightly shorter top tubes, longer head tubes, and are still sporty. Team Slipstream is pretty happy with their Felt Z-series bikes. I'd also recommend searching manufacturers' geometry charts for 57cm top tubes in combination with head tubes 17cm or longer. Fuji, Raleigh, and Kuota have models with shorter top tubes. Giant TCR geometry is pretty square, but the M-L has a 57cm top tube. With enough seat post, a flipped stem, and 175mm cranks, it might work.

[Longfemur]

The idea will be to buy a bike that won't be too long with a reasonable stem (say 80-110 mm long). If it has to be a smaller frame than leg length would indicate, no problem as long as he can get the seat high enough and far back enough. The latter can be a problem with smaller frame because they often have a steeper seat tube, and then the seat won't go back far enough because you run out of seat rail.

Another option would be to get the tallest frame he can ride and ride it with the handlebar higher up, to seat level.