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Discussion Starter · #1 ·
I just got sized up professionally at the LBS, using the bikefitting.com system and all of their measuring rack.. boy it was fun wearing lycra shorts topless having your shoulder width measured :rolleyes: but all better when a cute and innocent shortie turns up :thumbsup:

View attachment 53955

My friend is offering to sell his 2004 carbon composite frame with dura ace components on for a good deal to me. From the above diagram my D = 570mm and wb = 1001mm and distance from sadle post to bottom bracket (horizontally) is 171mm.

The frame is a size large and the geometry is below.

View attachment 53954

Would I be suitable for the frame with an appropriate stem / handlebars or do you think its a tad too large, could I get away with it if you know what I mean.

Any feedback appreciated, Thanks.
 

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more reach...

Based on your description, the custom bike has the same 73 degree STA. That means the reach is about 1.5cm greater on the carbon frame, so you would need a shorter stem-at least 10mm, maybe 20mm. I don't see a stem length on the custom frame drawing.

If the carbon frame has an integrated headset, the total stack height may be less. The HT length is also missing on your custom frame drawing.

What I can tell you is that the HT is only 5.5cm taller than mine, and your bars are about 9.5cm taller. It's quite likely that you would need a high rise stem to get that bar height. Depends on the total length of the HT, with the headset and spacers.

Bar height is usually measured to the top of the bars, so I just called it a 7cm drop, rather than 8.4cm.
 

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Discussion Starter · #3 · (Edited)
Thanks for the input :) I am new to road racing, have been on a mountain bike for the past two years.

It is a Giant TCR Advanced frame, one of the very nice T800 ones. I am not sure if it is an integrated headset or not.

The distance between the main vertical line that goes through the BB and the left hand side of the top tube is 232mm. So as the distance from this vertical line to the end of the handlebars stem is 483mm; adding the two gives a total of 715mm. The top tube length is 570mm on my 'custom' frame so the recommended stem length is 145mm. On a 15mm longer frame this means that my ideal stem length is 130mm, correct?

Would you say that a 7cm drop is good for me?
 

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not quite...

I won't bore you with the math, but the stem length on the drawing calculates to a 120mm, so you would probably need a stem in the 100-110mm range on the Giant.

If the bike's available, why don't you test ride it? To get an idaea of the fit, you should at least adjust the saddle fore/aft position and height.

www.coloradocyclist.com/bikefit
 

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getting by vs the right size

TI_roadracer said:
I just got sized up professionally at the LBS, using the bikefitting.com system and all of their measuring rack
...
my D = 570mm
...
Would I be suitable for the frame with an appropriate stem / handlebars or do you think its a tad too large, could I get away with it if you know what I mean.
Good to see you gone the full on fitting. If your LBS is saying that the top tube should be 570mm (ie D=570mm) then it looks like your friend's L frame is too big with a top tube of 585mm. Giant's smaller ML frame is right on the money at 570mm. Doesn;t sound like alot but if it justifies another size frame in Giant's range, one can only surmise that it makes a difference.

However, the good news is that your saddle to bar vertical drop is relatively short at 70mm (Not uncommon for a MTB rider but a roadie will commonly to drop say 100mm or even more sometimes). This means the larger size frame may suit you because the head tube will be relatively higher (ie less vertical drop to suit your taller stance).

I agree with C-40, the issue is going to be finding a stem that firstly is the right length and secondly gives you the right drop. Don;t worry too much about whether the head set is integrated (it is on the Giant). The best thing to do is to work out what the stem's required measurements need to be from the actual bike and take these to your LBS to see if you can get a reasonably sized stem to match (ie this will mean you can get by).

Last point: if you work on your flexibility, you maybe able to increase the saddle to bar drop to make you more aero on the bike (and go faster- I am assuming you have a fairly average body shape here). The catch with the L frame will be that you won't be able to drop the bars as low as the ML frame because the L's head tube is higher. To work out whether this is a problem, try measuring out a theoretical drop of say 100mm for another stem and see if the LBS can source that too. If so, the L frame just won't be just enough to get by but a good option as it will be able to adapt to any potential improvements in your flexibility later on.

Hope this makes sense! Good luck! :)
 

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sorry, can you clarify?

TI_roadracer said:
Problem is that it recommends a 585mm = 58.5cm frame size, this is 53.5 cm on the ML frame. Would having my saddle 5cm higher help?
Umm... this is getting confusing. :confused: From your bikefit drawing, 585mm is the seat tube length. The 585mm dimension on the L giant is the top tube length (ie D). These are different (ie wrong size).

The important measurement is concentrate on is the top tube dimension. From your original post, you said your recommended D is 570mm. Is this right? D on the ML Giant is 570mm too. This is a perfect fit.

In relation to the saddle, as you correctly pointed out, the seat post can just be raised to compensate the saddle height (within the safety limit of the seatpost).
 
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