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Discussion Starter · #1 ·
Didn't want to hijack another thread, so I'm starting a new one!

Trying to decide which size C50 frame would work best for me. I'm 66.5" with a 32.5" inseam. My current setup, which is completely dialed in, is as follows:

Look 595 Small
73cm saddle-BB
100mm stem
10cm drop

I'm pretty sure it'll be either 48s or 52 traditional, but not sure if one would leave me with too much seatpost, and the other with not enough. I appreciate any help.
 

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52 or 53 trad - probably the 53 as with the angles the reach (if i remember correctly) is only 0.5cm more, but the ST is 1cm higher.
 

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What exactly is too much seatpost or not enough? I find it hard to believe that you will not be able to adjust the seatpost to fit you. I have a 50 sloping that is the same as a 54 traditional and I have a 31.5" inseam. There is plenty of seatpost inside the frame, and that is a sloping frame. The 52 or 53 tradtional should be fine for you seatpost wise. The 48 sloping might require a lot of exposed seatpost. That is the only one I think might not work with your inseam even though I think the 48 sloping will work just fine with my inseam. I think I have more than a couple of inches of seatpost in my Cristallo's tube, so the 48 sloping should work for you too.

Just not too sure about the top tube length and going to a 12cm stem on a 48 sloping or 52 traditional.
 

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Discussion Starter · #4 ·
I guess "too much or not enough" mainly refers to the visual aspect of the bike. If my math is correct, the 48s would require me to have 20cm of seatpost visable (73cm - 48 ST - 5cm clamp= 20cm). In that sense, the 52 might work better.

As far as having to go to a 120mm stem, isn't it believed Colnagos handle better with a slightly longer stem? I thought I read an article stating Signor Colnago believed the rider should be "stretched out" on the bike.
 

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Yes, there is an article about that, and there are several people that say the article is BS. My 50 slopings handle just fine with an 11cm stem length and I chose something with an 11cm stem length just in case I wanted to go up or down. Turns out that I don't need to. Now, I also think a 13 cm stem on a 52 or 53 cm frame might look huge, and the amount of seatpost showing might also be a lot. I don't think Colnago frames in the 80's used 13 cm stems on all of them either. This subject was actually just covered in another thread in this forum just yesterday or the day before.

Just based upon a wheelbase view, for a single person a smaller frame would handle quicker, but the larger frame with the longer wheelbase would be more steady. Somebody please correct me if I am wrong because I am pretty much thinking and typing and I am not completely sure about this.
 

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Discussion Starter · #6 ·
I generally believe anywhere from 100-120mm works just fine. In my opinion, 90 would be a touch short, and 130 too long. I mainly want the frame that will fit me best... stiffness, comfort, and handling, with aesthetics thrown in for good measure. Because my current ride is sloping, I'm trying to find as many pics as I can to get a good visual of what the traditional will look like. The 48s is almost the same geometry as my 595, although the ISP makes up a lot of what would be seatpost on the Colnago. And, as I think you mentioned fabsroman, the 48s and 52 are basically the same geometry, albeit one has a sloping TT. Not sure if that is necessary due to my long inseam.

Which brings me to the question of what the stem length would be. Since the ST angle is the same on the C50 and 595, the only difference would be the HT angle. Can anyone tell me what it is on the C50? I think I'd be increasing only slightly from my current 100 to maybe 110 or 120?
 

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All else being equal, I would go for the traditional frame. It looks better, and from what I understand, a traditional frame creates a stiffer platform for seating riding than does a sloping. I have drafted behind guys on smallishley fitted sloping frames with lots of post exposed and been able to literally see the seat post slightly flexing back and forth as they pedal. Especially if you are coming off a Look 595 with an integrated post (very stiff post design) and you appear to have a very aggressive performance oriented fit, I expect that you probably would want to maintain more stiffness in the post area.
 

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Have you figured out what would be an optimal top tube length? Most of this discussion has focused on seat tube/seat post height. Top tubes on Colnago's tend to be shorter than other frames. Head tube angles are typically shallower than other bikes as well, but this should not affect reach as much as top tube length, seat tube angle and head tube height. I would suggest a fitting before ordering the frame; I have read to many threads on this site and others of guys having to order two frames before getting the right size. I bought a C40 from someone who had bought the wrong size frame.
 
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