# How to measure stack and reach of your current bike



## mrcreosote (Sep 9, 2010)

Good article from Velonews

Technical FAQ: Setting your bikes up identically


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## Kontact (Apr 1, 2011)

For each 1 degree off of level that your floor or wall is, that's going to change the measurements by 1cm, each. So either use only perfectly constructed rooms, or only use exactly the same section of wall and floor every time and understand that the measurements are not universally meaningful.


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## mrcreosote (Sep 9, 2010)

Kontact said:


> For each 1 degree off of level that your floor or wall is, that's going to change the measurements by 1cm, each. So either use only perfectly constructed rooms, or only use exactly the same section of wall and floor every time and understand that the measurements are not universally meaningful.


or use a carpenters square to make sure your measurements are perpendicular to the floor/wall


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## Kontact (Apr 1, 2011)

mrcreosote said:


> or use a carpenters square to make sure your measurements are perpendicular to the floor/wall


That only works if the wall and floor are already level or perfectly vertical.


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## mrcreosote (Sep 9, 2010)

Kontact said:


> That only works if the wall and floor are already level or perfectly vertical.


No - it works as long as your measurements are always at right angles to the floor/wall (like you get with acarpenters square) - the only real issue is if the wall and floor are out of square.

A measurement at right angles to the floor will always be correct, regardless of the slope of the floor.

A measurement at right angles to the wall will always be correct regardless of the slope of the wall.

example - lets say the floor slopes down 1 degree - I take a measurement of the height of the handlebars, ensuring I am measuring perpendicular to the floor. If the floor slopes down 3 degrees, I will still get the same measurement, because I am measuring the perpendicular distance, not the vertical distance

and you can always correct if the wall and floor are not at right angles to each other.


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## Kontact (Apr 1, 2011)

mrcreosote said:


> No - it works as long as your measurements are always at right angles to the floor/wall (like you get with acarpenters square) - the only real issue is if the wall and floor are out of square.
> 
> A measurement at right angles to the floor will always be correct, regardless of the slope of the floor.
> 
> ...


There is no real difference between saying that wall and floor angles cause problems and saying that they have to be square.

If your wall is perfectly vertical, but the floor slopes away at 1 degree, the measurement shown for reach to the handlebar from the wall is going to be 1cm longer than it really is.

And you usually can't measure from where the wall and floor meet because there is usually a baseboard.

If you have a huge square you can do all sorts of stuff, but the point of this technique is that it is supposed to work with just a tape measure. And it does, if the walls and floor are square, level, plum, whatever.


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## foto (Feb 7, 2005)

mrcreosote said:


> Good article from Velonews
> 
> Technical FAQ: Setting your bikes up identically


Stack and reach are really for gravity mountain bikes, ie: fitting bikes you ride primarily standing on the pedals. Don't waste your time.


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## mrcreosote (Sep 9, 2010)

foto said:


> Stack and reach are really for gravity mountain bikes, ie: fitting bikes you ride primarily standing on the pedals. Don't waste your time.


Sorry?? stack and reach are measurements based on a known reference point - the bottom bracket. It just gives you an idea of the relative position of the top of the head tube. what difference does whether you sit or stand make?


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## cxwrench (Nov 9, 2004)

foto said:


> Stack and reach are really for gravity mountain bikes, ie: fitting bikes you ride primarily standing on the pedals. Don't waste your time.


how'd you come up w/ this gem?


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## foto (Feb 7, 2005)

mrcreosote said:


> Sorry?? stack and reach are measurements based on a known reference point - the bottom bracket. It just gives you an idea of the relative position of the top of the head tube. what difference does whether you sit or stand make?


Because on a road bike, there are a lot of things you can tweak to make a bike feel very similar in fit to another bike, even one with a different geometry. Sure, wheelbase, turn initiation, etc will be a little different, but fit can be fiddled with. On a gravity bike, there isn't much you can tweak, and stem length/front wheel weight distribution are bigger issues in general for dirt than for road.


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## cxwrench (Nov 9, 2004)

foto said:


> Because on a road bike, there are a lot of things you can tweak to make a bike feel very similar in fit to another bike, even one with a different geometry. Sure, wheelbase, turn initiation, etc will be a little different, but fit can be fiddled with. On a gravity bike, there isn't much you can tweak, and stem length/front wheel weight distribution are bigger issues in general for dirt than for road.


you're shooting down your own argument...you can 'tweak' the fit on one bike to match another more easily IF you can compare the stack and reach of 2 different frames. don't tell me stack and reach aren't important, i use them daily. having these 2 dimensions on every bike models geometry chart would make my life much easier. explain to me how fitting a downhill bike is more complicated than fitting a road or tt bike...i'm all ears.


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## Scooper (Mar 4, 2007)

I invested in a Serotta X/Y tool a couple of years ago for setting up my bikes.


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## mrcreosote (Sep 9, 2010)

foto said:


> Because on a road bike, there are a lot of things you can tweak to make a bike feel very similar in fit to another bike, even one with a different geometry. Sure, wheelbase, turn initiation, etc will be a little different, but fit can be fiddled with. On a gravity bike, there isn't much you can tweak, and stem length/front wheel weight distribution are bigger issues in general for dirt than for road.


http://velonews.competitor.com/2011...ears-resolutions-for-the-bike-industry_154565

RTFA


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## foto (Feb 7, 2005)

cxwrench said:


> you're shooting down your own argument...you can 'tweak' the fit on one bike to match another more easily IF you can compare the stack and reach of 2 different frames. don't tell me stack and reach aren't important, i use them daily. having these 2 dimensions on every bike models geometry chart would make my life much easier. explain to me how fitting a downhill bike is more complicated than fitting a road or tt bike...i'm all ears.


No, a gravity bike is easier to fit. Mostly because you don't care about seat height, or seat tube angle. The bike is always ridden standing up.



mrcreosote said:


> http://velonews.competitor.com/2011/...ndustry_154565
> 
> RTFA


Don't be rude.


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## cxwrench (Nov 9, 2004)

foto said:


> No, a gravity bike is easier to fit. Mostly because you don't care about seat height, or seat tube angle. The bike is always ridden standing up.
> 
> 
> 
> Don't be rude.


don't be rude? i was rude? don't make uneducated statements about 'stack and reach' being something to ignore, and that is was devised for 'gravity' bikes. it was originally developed for tri bikes.


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## Kontact (Apr 1, 2011)

I think stack and especially reach are silly numbers. They reference a floating point in space making reach impossible to measure directly, and the reach number gets smaller the tall the headtube is, which makes simple comparisons between bikes involve a lot of math.

Our shop does a huge amount of fitting, and we reference everything to the BB and saddle on a level bicycle. If someone needs to know about comparative reach, we compare the TT adjusted for STA. That always works.


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## foto (Feb 7, 2005)

cxwrench said:


> don't be rude? i was rude? don't make uneducated statements about 'stack and reach' being something to ignore, and that is was devised for 'gravity' bikes. it was originally developed for tri bikes.


Edit: Actually I wasn't talking to you. Buuuut, I can make whatever statements I want. Don't take them personally. Life is too short.


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## BiketoLose (May 9, 2012)

*Informative*

This was a great read - very informative! Thanks to Roadbike review for providing this awesome resource.


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## cxwrench (Nov 9, 2004)

foto said:


> Edit: Actually I wasn't talking to you. Buuuut, I can make whatever statements I want. Don't take them personally. Life is too short.


that's a first! usually everyone thinks i'm an *ssh*le!


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## foto (Feb 7, 2005)

cxwrench said:


> that's a first! *usually everyone thinks i'm an *ssh*le!*


well, I am not sure that's not still the case here.


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## mrcreosote (Sep 9, 2010)

Kontact said:


> I think stack and especially reach are silly numbers. They reference a floating point in space making reach impossible to measure directly, and the reach number gets smaller the tall the headtube is, which makes simple comparisons between bikes involve a lot of math.
> 
> Our shop does a huge amount of fitting, and we reference everything to the BB and saddle on a level bicycle. If someone needs to know about comparative reach, we compare the TT adjusted for STA. That always works.


what do you mean 'floating point in space' - all they give you is the vertical and horizontal distance to the top of the head tube from the BB (or to use your own words, it references everything to the BB). If I look at two different frames, regardless of the geometry or design, I can tell which one is going to leave me too cramped or stretched out, or if I am going to be sitting up more or have to get down lower, or put more or less spacers under the stem.

And are you saying it involves a lot of math to work out the stack and reach? that is the whole point of trying to get manufactures give the numbers in the first place, so you don't have to work it out. How else am I supposed to know how much difference there is in two frames with the same TT but different STA/HTA/HT - reach gives me that in one number - it says this is how far in front of the BB you will have to reach, because the saddle setback from the BB i need will always be the same, regardless of the STA.

Example - I currently have a 57cm/XL Look KG461 (geometry here https://www.cyclesuperstore.ie/shop/pc/catalog/geo/look_geo.htm )

I want to buy a new frame - say a cyclocross frame https://i00.i.aliimg.com/img/pb/135/177/382/382177135_270.jpg

I think I might need the 56cm, or maybe the 58cm. How can I quickly see what is the right size if I want more-or-less the same fit as my current bike? In this case it is especially difficult because the TT size given is for the actual TT, not effective TT

As it turned out - I bought the 56, because the stack and reach numbers matched pretty closely to my current bike. I would not be able to tell that just by looking at the geometry numbers. And I also know what I need to get in terms of stem and handlebar to also match my current setup.


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## cxwrench (Nov 9, 2004)

foto said:


> well, I am not sure that's not still the case here.


hey, i work hard for that reputation.


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## mrcreosote (Sep 9, 2010)

foto said:


> Don't be rude.


Don't be ignorant


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## Kontact (Apr 1, 2011)

mrcreosote said:


> what do you mean 'floating point in space' - all they give you is the vertical and horizontal distance to the top of the head tube from the BB (or to use your own words, it references everything to the BB). If I look at two different frames, regardless of the geometry or design, I can tell which one is going to leave me too cramped or stretched out, or if I am going to be sitting up more or have to get down lower, or put more or less spacers under the stem.
> 
> And are you saying it involves a lot of math to work out the stack and reach? that is the whole point of trying to get manufactures give the numbers in the first place, so you don't have to work it out. How else am I supposed to know how much difference there is in two frames with the same TT but different STA/HTA/HT - reach gives me that in one number - it says this is how far in front of the BB you will have to reach, because the saddle setback from the BB i need will always be the same, regardless of the STA.
> 
> ...


The point in space is the one that you measure reach from. It floats above the BB, so you can't measure reach directly.

And you missed my other point. If you have two bikes with the same TT length and angles, but one has a slightly taller headtube, its "reach" number will be shorter than the other bike. But there is absolutely no real difference in reach between the two bikes. That's what happens when you measure distances between the converging lines of the angled headtube and the vertical line through the BB.

The math comes in when you want to compare two bike's reach and they have different stacks. 

The point in space that reach is measured from is arbitrary. There is nothing special about the distance to the top of the head tube. Virtual TT length is so useful because the seat tube and headtube are pretty much parallel, which means that stack doesn't change the number.


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## foto (Feb 7, 2005)

mrcreosote said:


> Don't be ignorant


Don't be funny.











Oh yeah, you're not. Nevermind.


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## cxwrench (Nov 9, 2004)

Kontact said:


> *The point in space is the one that you measure reach from. It floats above the BB, so you can't measure reach directly*.
> 
> And you missed my other point. If you have two bikes with the same TT length and angles, but one has a slightly taller headtube, its "reach" number will be shorter than the other bike. But there is absolutely no real difference in reach between the two bikes. That's what happens when you measure distances between the converging lines of the angled headtube and the vertical line through the BB.
> 
> ...


huh? how do you figure? everything is done from the center of the bb...


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## stevesbike (Jun 3, 2002)

25 impassioned comments on stack and reach - awesome! How about a new thread debating imperial units vs. metric?


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## foto (Feb 7, 2005)

stevesbike said:


> 25 impassioned comments on stack and reach - awesome! How about a new thread debating imperial units vs. metric?


No, I disagree.


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## Kontact (Apr 1, 2011)

cxwrench said:


> huh? how do you figure? everything is done from the center of the bb...


Reach is a horizontal measurement. If you can show me how to measure reach from the BB with nothing more than a ruler, my hat is off to you.

In reality, you can't measure reach without some sort of frame, very large square or a plumb wall and level floor. The point reach is measured from is not on the bike, it is a point floating over the top tube, and you can't put a ruler on that point.


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