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with the 2008 new design the TT are all shorter. i was looking at buying a cross frame to build up and was comparing my 06madone for size. i then looked at 08madone and also saw the new changes.
 

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Not necessarily short.

It's difficult now to interpret Madone geometry from the less-than-clear geometry chart frame drawings. Madone 5.1 through 6.9 are now measured (both for nominal frame size and effective top tube length) to a "v" dot on the seat mast. In my view, that way of determining nominal frame size leaves Madones running small (as they always have) compared to other bikes—making top tube lengths normal (or perhaps even longer than normal) for a given frame size.
 

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No...

There are two issues here. The 6 series frames have different geometry than the 5.5 and lower level models. The lower levels have much taller head tubes.

In either series, the frame size number is meaningless. What you have to consider for the vertical frame size is the head tube length. Trek appears to be using a common 15mm headset top section, which add another 15mm to this length.

As an example, a 54cm Trek 6 series has a little shorter head tube (120mm) than a 51cm LOOK, but the LOOK is an accurate 51cm c-c size. The 5 series frame of the same size has a very tall 150mm head tube.

In addition to the TT length, the seat tube angle has to be considered. Steeper STAs increase the reach, once the saddle is moved back to the same position as some other frame with more slack STA.

The reference point that has been mentioned denotes the opposite end of a horizontal line from the top-center of the head tube. These two points define the reach value. The problem with reach values is they are only good for one specific head tube length or frame stack value. You can't compare the reach values of two different sized frames and get an accurate value for the difference in stem length.
 

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C-40 said:
There are two issues here. The 6 series frames have different geometry than the 5.5 and lower level models. The lower levels have much taller head tubes
Not quite. Excluding WSD, two fit options are available for all 5.2 through 6.9 Madones: so-called "Pro" and "Performance" fit. Performance fit is, again in Trek's words, "30mm taller than the Pro fit."
The Trek geometry chart frame drawings may not reflect this, and may actually be misleading in this regard.
 

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You're going to have to test ride one. You might be split between two sizes. Most Trek dealers seem to have an over abundance of Trek bikes on their show room floor. It should not be difficult to arrange a test ride. See if they will let you take it for a ten miler at least. Bring your pedals and saddle. I did this when I bought my current bike and it was the deciding factor.

Of course you might end up with a different bike, I was not shopping for a Trek when I bought mine.
 

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Discussion Starter · #7 ·
it would seem I'm in between

I was looking for a size 56 bike with a 56 to 56.5 TT. I recall the old Trek 5200 OCLV had a TT of about 56.4 or so and I was surprised when I looked at the Madone geo charts. Kind of wierd b/c even the compact frames in size M or L seem to have a 56 "virtual" TT size.
 

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If you're keen on a precise fit . . .

jimmyihatetoregister said:
I was looking for a size 56 bike
. . . looking for a certain size number bike doesn't work anymore. Because of all the different frame configurations and different (some would say screwy) ways of measuring frames, a size number (like "56") is meaningless. Someone's 56 could fit you exactly like someone else's 53.
 

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thanks...

wim said:
Not quite. Excluding WSD, two fit options are available for all 5.2 through 6.9 Madones: so-called "Pro" and "Performance" fit. Performance fit is, again in Trek's words, "30mm taller than the Pro fit."
The Trek geometry chart frame drawings may not reflect this, and may actually be misleading in this regard.
I didn't catch the "pro" series as the only ones with shorter head tubes.
 

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comparison..

jimmyihatetoregister said:
I was looking for a size 56 bike with a 56 to 56.5 TT. I recall the old Trek 5200 OCLV had a TT of about 56.4 or so and I was surprised when I looked at the Madone geo charts. Kind of wierd b/c even the compact frames in size M or L seem to have a 56 "virtual" TT size.
An older "56cm" Trek had about 120mm head tube, plus about 30mm for the headset, for a total of 150mm. The actual c-c size was only about 52.5cm. The TT was 56.1cm with a 73.5 degree STA. The TT length was actually longer than just about any other brand in the same size,

A new 56cm pro series will have a total head tube length that is about 155mm with the headset, a 55.7cm TT and 73.6 degree STA. The fit isn't much different and the TT length is not short for this size.
 
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