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I have been measured once, then twice and found out that my ideal top tube size is 570mm with a seat tube angle of 73.5o. I want to go with a Scott CR1 bike, but am stuck in between sizes of:

1. Large, 560mm top tube + 130mm stem, with a 73.5o STA

2. Extra Large, 575mm top tube + 115mm stem, with a 73.3o STA

I also have the choice of a Giant TCR, in an ideal size top tube size but a too shallow seat tube angle,

3. M/L, 570mm top tube + 120mm stem, with a 72.5o STA

I am leaning towards the Scott as I prefered the ride of the bottom line Scott in size Large (1), with 105 groupset and bottom line ksyrium wheel set, in comparison to a Giant TCR C1with ultegra and ksyrium SL's, the Scott was stiffer, more responsive with a greater power efficiency and it was also less twitchy in my opinion. But I know the Scott isn't as fast as handling compared to the Giant TCR C1, so I think a size XL with a longer stem will be better, especially as I stretch out overtime.

How do I calculate handle bar drop from the frame geometries here:

http://www.scottusa.com/product.php?UID=7516&feature=geometry

Any comments guys because I am going to purchase my racing bike for CAT 3 racing (UK system) this weekend.

Thanks in advance :D
 

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a little off...

The 72.5 STA on the Giant reduces the frame reach, so you'll need a 130mm stem, the same as the size L Scott.

You'll have a tough time finding a 115mm stem, so you'll have to choose what to do with the reach and saddle fore/aft to take care of the 5mm difference.

You haven't compared head tube lengths. If you don't know your "ideal" handlebar height, you should figure this out. It's not tough to figure the amount of spacer and stem angle needed, if you pick a HT length.

The M/L Giant has a 160mm HT, the Scotts have 170 and 190mm HTs.
 

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Sounds like the Large will fit you fine. 130mm stem shouldn't be a problem.

However, if you prefer faster handling and plan to use a more stretched out position, you might want to consider the X Large.

TI_roadracer said:
I have been measured once, then twice and found out that my ideal top tube size is 570mm with a seat tube angle of 73.5o. I want to go with a Scott CR1 bike, but am stuck in between sizes of:

1. Large, 560mm top tube + 130mm stem, with a 73.5o STA

2. Extra Large, 575mm top tube + 115mm stem, with a 73.3o STA

I also have the choice of a Giant TCR, in an ideal size top tube size but a too shallow seat tube angle,

3. M/L, 570mm top tube + 120mm stem, with a 72.5o STA

I am leaning towards the Scott as I prefered the ride of the bottom line Scott in size Large (1), with 105 groupset and bottom line ksyrium wheel set, in comparison to a Giant TCR C1with ultegra and ksyrium SL's, the Scott was stiffer, more responsive with a greater power efficiency and it was also less twitchy in my opinion. But I know the Scott isn't as fast as handling compared to the Giant TCR C1, so I think a size XL with a longer stem will be better, especially as I stretch out overtime.

How do I calculate handle bar drop from the frame geometries here:

http://www.scottusa.com/product.php?UID=7516&feature=geometry

Any comments guys because I am going to purchase my racing bike for CAT 3 racing (UK system) this weekend.

Thanks in advance :D
 

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missing info...

TI_roadracer said:
My Ideal handle bar drop is 74mm for training and 100mm for racing, with a angle of 12o on the stem. Would the 190mm head tube on the XL Scott allow for this?
You can't figure drop without a saddle height. Drop can be estimated using the normal measurement from the center of the BB to the top of the saddle, along the center of the seatpost.

A 2.5cm difference in drop between "training" and "racing" seems kind of large to me, but maybe your races are short, so the larger drop is tolerable.

The angle of 12 degrees - what type of measurement is that? 12 degrees from horizontal?
 
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