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Top Tube Length????(6 posts)

Top Tube Length????rickbr
Oct 27, 2003 7:26 AM
I'm thinking of buying a Kelly CX Frameset. Kelly builds with a shorter top tube length 55 c-c on the 55cm frame.
This seems to be my size 55X55 because the standover on the
57X57 is too tall. But some builders (Steelman, IF) build basically the same size frame 54 c-c with a longer top tube,
57 c-c. Which is better or is it personal preference, a short or a long top tube, my road bike is 56x56 cm c-c.
Thanks!
re: Top Tube Length????flyweight
Oct 27, 2003 9:57 AM
First, a longer top tube doesn't always mean a longer reach to the handlebars. This is a myth perpetuated by people who clearly failed geometry in high school. There's a lot more to frame geometry and fit than simply top tube and seat tube.

What you need to do is figure out where your body needs to be and then find a frame that will fit that. The two most important numbers you need to know are seat height and set back. These numbers determine where your butt is relative to the bottom bracket. One you have that dialed in you figure out your front center. You make adjustments in reach by changing stem length not by sliding your saddle forwards and backwards as so many people mistakenly do. So long as you fit the frame and don't have to resort to an unusually long or short stem then the frame fits. Obviously a frame that requires a shorter stem is going to handle differently than a frame that needs a longer stem. Also a frame that places more of the top tube behind the bottom bracket is going to ride differently than a frame that places more of the top tube ahead of the bottom bracket. At this stage it becomes a matter of personal preference.
If it helps...Chicago_Steve
Oct 27, 2003 12:27 PM
I have a 55x55cm Kelly. I'm a long leg short/short torso kind of guy...

Height - 5'11"
Inseam - 33.5"

I'd probably get nailed by the stem police as I am using about 2 cm of spacers and a 110mm length stem BUT I'm about as flexible as a parking meter so this bike fits me pretty well.
If it helps...rickbr
Oct 27, 2003 12:41 PM
I'm almost identical in height/inseam, also 48 yrs old, I was most concerned about being too cramped on the bike with the 55cm top tube.
If it helps...flyweight
Oct 27, 2003 3:47 PM
2 cm of spacers isn't that much. I've got that many on my bike and I have my WCS stem flipped to it's highest setting. The overall position isn't that different from my old, pre-threadless cross bike. Most threadless headsets have a much lower stack height than the older threaded headsets and in the old days most people had their stems raise 10-30mm above the top of the headset. Translate that position over to today's low stack threadless headsets and having that many spacers isn't so strange.

One big problem I'm seeing with a lot of production road bikes these days is the use of internal/integrated headsets. Many companies use them and also cut the steer tube on the fork really short often allowing only 1-2 small spacers. That's a fine position for racing but very few people are that flexible. Guess the companies only care how it looks in the magazine ads! No wonder so many people are buying flat bar road bikes/comfort bikes instead.
short is okcation9
Oct 28, 2003 7:06 PM
I am 6 ft. even, have a 34" inseam, and normalish torso/arm length. i ride a 55 seat-tube with 55.5 top-tube bianchi axis with a 120mm 5deg rise stem with about 2cm of spacers. of course the seat is jacked up pretty high, but i have the shifter hoods a comfortable 2 in. below my saddle. if you go to a cross race you will see many riders going down a size on the top-tube/frame. cross racing has lots of cornering and technical riding. having a shorter cocpit and wheelbase helps you shift your weight better. if you are as stretched out as you are on a road bike you will not be as agile. of course many riders also size their bikes just as for road riding, so you see both.

happy riding, will