LX302

OK, I've been a cyclist for many years.
Back in '86 I had an Fuji and it was a 23" frame.
In '89 I bought a Trek 1200 60cm frame w/a 57 top tube and road it for years, but eventually got out of cycling and sold it.
Well 17 years later I bought a MTB and pedalled all last year on the trails, and got the cycling bug again and wanted to try road biking again.
I've been debating on what size frame is right for me, as the geometry has changed somewhat since the 80's.
According to all the fit calculators, I would need a 60cm frame but with a top tube of 56-57cm.
Well most new bikes don't support that top tube geometry. I used the competative cyclist site, and find that to be the best of them all.
So do I go with a 60-61cm frame with a top tube of 57.0 to 57.5cm's or a 57-59cm frame with 56-57 top tube?
I've read that the top tube is the most important dimension to hold, but would I be able to raise and lower the stem enough to compensate for the smaller height difference?
I guess a trip to the LBS might help in determining that, but just a short ride around the parking lot doesn't really seem isn't going to tell me a whole lot as far as fit and comfort.
What are you thoughts on my questions/concerns?

biker7

the top tube is very important but no more so then the seat tube angle and the head tube length. Those are the big three to consider. Many tall riders like myself have long legs. That means the seat is raised pretty high. I need a relatively small seat tube angle to achieve KOPS even with a set back seat post. 1/2 degree seat tube difference changes the effective top tube length. With a high seat due to long legs, I need a long head tube or my handlebars will be way below my saddle height which I find uncomfortable over 20 miles which I ride all the time. Trial and error I believe is still the best teacher when it comes to fit. Remember which bike you found the most comfortable. Knowing its measurements allow you to duplicate your riding position on another frame.
HTH,
George

alanbikehouston

A controlling measurement for comfort on a road bike is the distance from the rear of the saddle to the front/center of the brake levers. I have six or eight road bikes around at any given time, and all have different top tube measurements. But, the RS to FBL measurement is the same on each of them: Between 38 1/2 and 39 inches.

Getting that 39 inch RS to FBL measurement is easiest on a traditional frame that is about size 58 to 60, measured to the top of the top tube. That size frame makes it easy to raise the bars so that the top of the bars is at the same height as the top of the saddle. Then, add a shorter or longer stem. Adjust the fore/aft of the saddle. I can switch from bike to bike and have precisely the same riding position on all of them.

The problem with the current "fad" of putting average riders who are 5'10 or 5'11" on frames that are a tiny 54 or 55 in size is that the bars are far too low. Even with a short top tube, after the saddle is at its correct height, the RS to FBL can end up at 40 inches or more...too long a stretch for most week-end riders (although apparently suitable for pro cyclists...many of them ride "mini" bikes).

Bottom line: if you were comfortable on the Trek 1200 with a size 60cm frame, look for bikes that would give you a similar fit. With "compact" frames, look for a bike that provides a bar height at least as high as that on a "traditional" size 60.

biker7

Alan...an insightful post. Have never seen it put in quite those terms but a linear measurement from the back of the saddle to the brake levels which takes into account not only horizontal but vertical components of reach is great way of considering proper fit. Isn't it ironic if not a bit counter intuitive that a bigger frame bike can have actually a shorter reach taking into account vertical and horizontal reach as your measurement technique does not to mention most larger frames have a more slack seat tube angle which further reduces reach when achieving KOPS relative to effective top tube length. You and I are on the same page when it comes to road bike sizing and why I ride a large and not small frame for my body size as well.
Cheers,
George