I'll continue with the fit theme of the earlier thread. For all you folks out there with lots of riding/bike fit experience, young and old please chime in:

Recent measurement:

174.5 Height
82.7 inseam

Current Bike

55cm ST ctr to top
54 cm TT ctr to ctr- horizontal
74 seat tube angle
72.5cm saddle height center of BB
90cmcm grip height- measured from groung to top of brake hoods
86cm cockpit-measured from direct line, center of BB to center of the stem/bar intersection
78.5cm Handlebar reach- measured saddle tail to stem/handlebar intersection
100cm Stem- 84 degrees- 2.5 cm of spacers
? don't know HT height but its an Italian frame

New Bike

51.5 cm ST ctr to ctr
54.6 cm TT ctr to ctr-- 6 degrees of slope
73.5 cm seat tube angle

16.5 cm head tube height
1.0 cm head tube extension
80.5 cm standover- estimated
72.5 cm saddle height
77.8 cm reach from saddle tail to handlebar
3.4 cm diff between saddle top and stem center

I don't know why but I'm thinking shorter ST, more slope and shorter HT. I want a compact but I'm not sure if the above will have smooth lines and curves. I'm confident it will fit but not a lot of standover room.I rode the lbs owner's bike and it was similar only shorter ST (42), smaller HT (12.4) and more slope, 10 degrees. It felt ok except for the distance from saddle to hoods- to much and he has about 2cm of spacers and a 84 degree stem, 10cm

You're apparently getting confused by the sloping TT frame terminolgy. Any decent frame drawing for a sloped TT frame should list it's c-c "size" as if it had a horizontal TT. With a 6 degree slope, the c-c seat tube should be at least 5.5cm less than your current frame, or 48cm to be approximately the same size. The frame you're considering is vertically too large.

The head tube length, with the headset is very important. Since you're using 2.5cm of spacer, the head tube, with headset should be taller on a new bike, unless you're willing to change to a higher rise stem. To produce a 90cm handlebar height (not "grip height") with an 84 degree stem, you need a total length of about 180mm, with the headset and spacers. Grip height is not a good measurement for comparison, since it vareis greatly, depending on the type of handlebar and the chosen placement of the brake/shift levers. Measure your handlebar height from the ground to the top of the bars. Even this measurement must take into account any change in the BB drop, if the proposed frame differs much from the pretty standard 7cm drop.

To compare the horizontal fit of two frames, the reach dimension tells everything. Reach is the horizontal TT length minus the setback. Setback, if not listed, is the cosine of the STA times the frame's c-c size with a horizontal TT.

The reach of your current frame is approximately 39.3cm.

Below is the website with about the best frame drawing available. Pcc is the c-c frame size, O is the horizontal TT length and Sc is the setback. To make accurate comparisons between brands or models, the frames should be the same c-c size.

http://www.trialtir-usa.com/2005-colnago/colnagoinfo/colsizecharts.htm

The goal for new frame should be to correct a know fit problem. For instance, I'd want about a 2cm taller headtube than your current bike to eliminate most of the spacers. A 1cm shorter TT length might be desirable to use a 110mm stem, but this will shorten the wheelbase and create more toe overlap.

Thanks C-40. Thats the first thing that jumped out when I saw the specs- too tall. They had come back intially with a recommended 9-10 degree slope using my 10cm 84 degree stem and 2cm of spacers. I have not seen the other measurements on this frame but will ask for it tomorrow. I assume the ST would be at least a few cm shorter.

I nixed more slope mainly due to aesthetics and to much seatpost exposed. Now I'm thinking that if I went with a 48 cm ST c-c and more slope I will still be able to use my 350 mm Ritchey post. When I road the shop owner's bike ( 42 cm ST) I still needed to raise my post a bit but was at the max line.

Is a 165 mm HT gonna look out of proportion on either of these sizes? I'm off to measure the HT on my Gios and resubmit for new specs. Where does all the fit experience come by C-40? Trial and Error, bike industry????

I've been riding for over 20 years and being a mechanical engineer doesn't hurt either.

As for the HT length, if you're using a conventional headset, like a King with about a 3cm stack height, then all you need is a 150mm head tube to get the top of the bars up to 90cm, with NO spacers. If you think you may need more than a 1cm reduction in bar height, which you could get with an 80 degree stem, then the head tube could be even shorter.

Something like Colnago's 510 x 532 sloping frame is what you need.

How much slope would the Colnago above have ?

Subtracting the Pccs from Pcc, you get 4.5cm., which is about a 4.5 degree slope.