I already have a Specialized Tarmac Sl4 in size 58 with a 110mm 6 degree stem (25mm spacers). My saddle height is 79cm. I need a zero setback seatpost on the Tarmac to have an optimal power transfer. I really love the Tarmac and the fitting on the Tarmac feels correct.
The Storck C1.1 has a top tupe lenght horizontal of 57.5cm and I use a 120mm 6 degree stem (33mm spacers). I have a Ritchey seatpost with25mm setback. The fitting on the Storck feels also correct, but I need more spacers then on the Tarmac because of the headtube lenght. I can also use a 25mm setback on the seatpost. I find a seatpost with 25mm setback more beautiful then a seatpost with zero setback.
The Question: Which framesize do I need for a Colnago C59 slooping taking the above information into account? I think I need the 56s. Correct?
Which framesize for a Pinarello Dogma 65.1 Think 2? The Pinarello is a traditional frameset with a horizontal top tube. I think that I need a CC 57.5 with a toptube lenght of 57.5 and a headtube of 179mm. Correct?
Thanks for your help!
I found some more information of my body fitting. I don't know exactly what I am looking at. I got it from the shop where I bought the Tarmac but I never paid attention to it until recently.
Step 1. Vertical distance between top of seat and bb centre using sides 233 (seat setback) and 788 (seat height) is 752.76, and seattube angle is 72.8deg.
Step 2. Calculate Stack as 752.76 less 83 drop = ~670. Note that this is top of seat to centre of bars. (Eg frame Stack is close to 629 if stem stack is 42 and headset stack is 20)
Step 3. Using 738 and 83 drop, horizontal dist between seat centre (where is this seat centre? This is why I use seat rails centre) and handlebars centre is 733.32.
Step 4. Calculate Reach as 733.32 less 233 seat setback = 500.32. To get frame Reach you can subtract stem length eg 490 if 110 stem
You need a little bit of maths to check from geometry charts whether you can get your seat and handlebars where you want them.
So according to my calculations you could pick a 560 Dogma, and try to get your bars raised 60mm.
My versions of Setback, Stack and Reach are:
Setback: Horizontal distance between centre of seat rails (easy to mark and set this point with a little piece of electrical tape etc) and vertical line of bottom bracket centre.
Reach: Horizontal distance between centre of seat rails and centre of handlebars clamp.
Stack: Vertical distance between bb centre and centre of handlebars clamp.
Seat height: Better (for me) to use vertical distance between bb and centre of seat rails. If measuring along seat tube you have to be mindful that the seat tube on your frame may not be centred over the bb.
The maths say that you'll need to raise your bars 60mm, with a stem with rise and/or spacers on a Dogma 560.
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