Back to frame size

[Kobie]

The topic was raised on another forum after an ad was placed for a 56cm bike. There was some discussion on length and frame size, which made me wonder if I have the right size bike, as I had the lift the handlebars, shorten the stem and move the saddle forward on a 56cm Trek.

Well, I had myself measured and the computer came up with the following:

Total length 176cm.  In Seam length 86.5cm

Results:

Seat tube 560 - 565

Top tube 568 - 574

Others not so important ito frame size.

 

The verdict is that my frame size is correct, but because I sit in a more upright position, I had to make these adjustments and can possibly go for a 54/55cm????

 

 

 

[Canaris]

KObie, a right sized frame is one that fits.

 

 

 

Each manufacturer has their own geometry. each bike is diferent. You might fnd that a raleigh 55cm (m) works for you, others may not. When buying a bike check the geometry of the builder and then the frame size. A 51cm Eddy Merckx is as long as some 54cm bikes but stand over is the same as some 49cm bikes. Go figure.

[AndreZA]

Top tube length is all that counts these days. And then not even. Whatever is comfortable. Looking at your measurements, I will stick with a 56cm frame. They are normally "square". This means that the seat and top tube is the same length (on a regular non-compact frame).  On a Giant it should be about M with a 110-120mm stem or a M/L with 90-100mm stem.

 

 

[linnega]

It is actually your effective top tube length that matters most - obviously irrelevant to the straight top tube of the Trek, but definitely relevant to the top tubes of the Raleigh's and Giant's of this world. 

 

If you are able to find comfort without moving the stem past reasonable limits, having too many spacers, the seatpost past its safety line or the saddle beyond the rail limits then you have a bike that fits you.  More often than not some adjustment is needed from the calculated fit as everyone is very different. 

 

My road bike fits almost spot in the middle of the range with everything ie 3cm or so of additional useable seatpost, not too many spacers, a 10cm stem and the saddle rails right in the middle.  However, my MTB which I feel even more comfortable on has the seatpost right on its limit, the seatpost rails on their limit and the extra spacers were only removed by fitting a riser bar.  Both are comfortable and for me a great fit.