# FC Stack Height



## woodys737 (Dec 31, 2005)

Felt published a stack of 526mm for their 54 FC. 526mm is measured from the center of the BB to where exactly? Top of HT or center or TT where it joins the HT? 

Thanks


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## Superdave3T (May 11, 2009)

woodys737 said:


> Felt published a stack of 526mm for their 54 FC. 526mm is measured from the center of the BB to where exactly? Top of HT or center or TT where it joins the HT?
> 
> Thanks


Stack is defined from center of BB to the center of the top of the HT at the top tube.
-SD


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## PJ352 (Dec 5, 2007)

View attachment 268918


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## woodys737 (Dec 31, 2005)

Thanks gents. My current ride fit perfectly between the 54 and 56 FC. lol!


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## PJ352 (Dec 5, 2007)

woodys737 said:


> Thanks gents. My current ride fit perfectly between the 54 and 56 FC. lol!


If you're literally between sizes, your current bike fits you well and suites your style of riding, I suggest looking at your current reach (effective top tube + stem length), then drop (stem angle/ spacer setup). Compare those values to the 54 and 56 FC and estimate how the changes in their reach/ drop affect how you'd configure both.

It's generally easier to start with your current stem length. If it's on the short side and going to the 56 would increase reach, the 56 might not be the best choice. The opposite would hold true for the 54. 

Then again, you may already know all of this...


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## woodys737 (Dec 31, 2005)

PJ352 said:


> If you're literally between sizes, your current bike fits you well and suites your style of riding, I suggest looking at your current reach (effective top tube + stem length), then drop (stem angle/ spacer setup). Compare those values to the 54 and 56 FC and estimate how the changes in their reach/ drop affect how you'd configure both.
> 
> It's generally easier to start with your current stem length. If it's on the short side and going to the 56 would increase reach, the 56 might not be the best choice. The opposite would hold true for the 54.
> 
> Then again, you may already know all of this...


Thanks PJ. I have a nice spread sheet going and pretend I know more than I do! lol! Here's the difference in Reach/drop:

The 54's reach is the same and the drop -9mm. So, more spacer = not ideal but ok.
The 56's reach is 12mm longer and the drop is +13mm. Less spacer = good.

Either frame will work fine and I have stems from 110 to 130 to get the reach. What concerns me and what I'm trying to gauge is where the tip of my saddle will be oriented in relation to the BB center. I ride it right at 5cm behind at the moment and would like to preserve this distance. Again, not a huge deal as I can get a 25mm setback post for the 54 and if needed a zero for the 56. 

The last area of concern is the front center and chainstay lengths. The 54 is -15mm front and -3mm on the stay while the 56 is -7 front and -3 stay. Wondering if this will be noticeable?

Thanks for the insight. I do appreciate it as I ride and race quite a bit. I realize I'm splitting hairs but it is a chunk of money being spent and want to understand what I'm buying. In the end I'm sure both frames will function better than what I need.


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## PJ352 (Dec 5, 2007)

woodys737 said:


> Thanks PJ. I have a nice spread sheet going and pretend I know more than I do! lol! Here's the difference in Reach/drop:
> 
> The 54's reach is the same and the drop -9mm. So, more spacer = not ideal but ok.
> The 56's reach is 12mm longer and the drop is +13mm. Less spacer = good.
> ...


I don't think you're splitting hairs at all. getting fit right is always important, especially when competing.

When comparing ETT's, don't forget to factor in ST/ HT angles and HTL differences, because they'll affect reach.

Assuming your current bike fits well, its reach/ drop measurements could serve as your baseline. From there, you'd estimate the changes required on both the 54 and 56, but unless you're running a short stem on your current bike, adding 12mm's might pose more of a problem than the added ~1cm drop on the 54. Something to consider....

Re: setback, I prefer measuring for KOPS than setback. Doing so avoids calculating for the differences in STA and saddles (if any), so is a more 'direct' measurement. The only time I'd use setback is to duplicate set ups or when all relevant parameters are consistent.

JMO, but zero setback posts should be reserved for TT/ tri bikes and ill fitting bikes where the rider is 'making due'. In other words, they're an unnecessary compromise to be avoided. 

Bottom line, as close as possible, I'd try to pin down the reach/ drop numbers, then estimate stem length/ angle/ spacer configurations for both the 54 and 56.


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## woodys737 (Dec 31, 2005)

PJ352 said:


> I don't think you're splitting hairs at all. getting fit right is always important, especially when competing.
> 
> When comparing ETT's, don't forget to factor in ST/ HT angles and HTL differences, because they'll affect reach.
> 
> ...


I'm definitely trying to duplicate my current set up. I trust the fitter that fit me last and he's well known in the fit world fwiw. 

Stack and reach are very close with the 54. I ride a 52s Colnago CX-1 at the moment and the STA's are .3 degrees steeper on the Felts. The HTA on the Colnago is a bit of a mystery as it's not published and has been hard to find. I've read it's anywhere between 71.5 and 72.5 degrees. The ETT on the 54 is 5mm shorter while the 56 is 10mm longer. In effort to preserve the BB relationship I think I'd have to slam the saddle fwd on the 56 to the limit with a 25mm setback post. Totally agree about the zero setback post and want to avoid that which is another vote for the 54.

Thanks again!


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## PJ352 (Dec 5, 2007)

woodys737 said:


> I'm definitely trying to duplicate my current set up. I trust the fitter that fit me last and he's well known in the fit world fwiw.
> 
> Stack and reach are very close with the 54. I ride a 52s Colnago CX-1 at the moment and the STA's are .3 degrees steeper on the Felts. The HTA on the Colnago is a bit of a mystery as it's not published and has been hard to find. I've read it's anywhere between 71.5 and 72.5 degrees. The ETT on the 54 is 5mm shorter while the 56 is 10mm longer. In effort to preserve the BB relationship I think I'd have to slam the saddle fwd on the 56 to the limit with a 25mm setback post. Totally agree about the zero setback post and want to avoid that which is another vote for the 54.
> 
> Thanks again!


Not trying to (overly) inject my thoughts/ opinions here so feel free to disregard, but a couple of thoughts...

Yes, Colnago's generally have slack(ish) HTA's, and considering that for every degree of change there's only ~ 3mm change to reach, I wouldn't fret over that parameter. A degree of STA change makes for ~8mm's of change to reach, so your .3 change would equate to about a 3mm change to ETT (reach).

Also, all else being equal, the taller the HT, the shorter reach will be.

Since I'm a believer in the right geo (for a given rider) means the saddle is generally placed mid-rail, what you've offered re: the saddle position on the 56 would close the door to that option IMO, but this is going to be your bike, not mine.


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## woodys737 (Dec 31, 2005)

PJ352 said:


> Not trying to (overly) inject my thoughts/ opinions here so feel free to disregard, but a couple of thoughts...
> 
> Yes, Colnago's generally have slack(ish) HTA's, and considering that for every degree of change there's only ~ 3mm change to reach, I wouldn't fret over that parameter. A degree of STA change makes for ~8mm's of change to reach, so your .3 change would equate to about a 3mm change to ETT (reach).
> 
> ...


Many thank JP. Great info re change of HTA and STA and how it changes reach. I think the 54 will work very well.


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