# Stem flip changes what parts of bike fit?



## milkbaby (Aug 14, 2009)

Not sure which forum to ask this, but as a newbie I figure here would be okay...

Outta curiosity, if I flip the stem on my bike, what parts of the bike fit will that alter or require changes to (right now stem angles upwards)? Will it change the reach and require moving the seat forwards? But I thought the seat forwards and backwards sets up your knee position over the pedals? As a newbie, should I even worry about it cause I feel comfortable with hands on the hoods and in the drops the way the bike is already set up? Just curious...


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## PJ352 (Dec 5, 2007)

milkbaby said:


> Not sure which forum to ask this, but as a newbie I figure here would be okay...
> 
> Outta curiosity, if I flip the stem on my bike, what parts of the bike fit will that alter or require changes to (right now stem angles upwards)? Will it change the reach and require moving the seat forwards? But I thought the seat forwards and backwards sets up your knee position over the pedals? As a newbie, should I even worry about it cause I feel comfortable with hands on the hoods and in the drops the way the bike is already set up? Just curious...


Flipping a stem (up or down) changes what's called stack height. Depending on the amount of angle change, reach can be affected, but it's small in relation to the angle change. 

For example, if you had a 73 degree HT angle, 100 mm, 6 degree stem flipped down (meaning -6) and flipped it up (+6) you'd change stack height (raise the bars) about 20 mm's and reach would be 6 mm's less.

You're correct that saddle adjustments should not be made to compensate for reach or drop, but if you were to lower the bars substantially, it might require a change to saddle tilt, because your pelvis would be rotated forward slightly, possibly putting excessive pressure ahead of the sit bones. This is but one example of how changing fit can cause a seemingly unrelated problem somewhere else. It also points up the importance of making small changes, slowly.

If you're comfortable with fit 'as is', I'd leave it alone for the time being. Fit does evolve, but it's a slow process and takes some saddle time. As you fitness increases, you _may_ find that you'd prefer more saddle to bar drop, but let that be a naturally occuring process, rather than a goal.


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## Opus51569 (Jul 21, 2009)

PJ352 said:


> Flipping a stem (up or down) changes what's called stack height. Depending on the amount of angle change, reach can be affected, but it's small in relation to the angle change.
> 
> For example, if you had a 73 degree HT angle, 100 mm, 6 degree stem flipped down (meaning -6) and flipped it up (+6) you'd change stack height (raise the bars) about 20 mm's and reach would be 6 mm's less.
> 
> ...


Listen to PJ352... his kung fu is strong...


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## PJ352 (Dec 5, 2007)

Opus51569 said:


> Listen to PJ352... his kung fu is strong...


You had a role in this as well, Opus. You provided the example! :thumbsup:


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## Kerry Irons (Feb 25, 2002)

*Stacking it*



PJ352 said:


> Flipping a stem (up or down) changes what's called stack height.


Historically, stack height referred to the headset height, not the handlebar height.


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## PJ352 (Dec 5, 2007)

Kerry Irons said:


> Historically, stack height referred to the headset height, not the handlebar height.


Good point and I stand corrected. I was thinking of it as a variation of frame stack, but that doesn't apply. Surprisingly (to me), Sheldon Brown (RIP) includes the stem in the case of threadless steerers, but not spacers.

*Stack Height*
The stack height is the vertical space taken up by the headset. With a conventional threaded fork, the steerer tube is longer than the head tube by some amount. If a headset is chosen with a stack height greater than this difference, there may not be enough of the steerer free above the upper bearing race for the keyed washer and lock nut to be installed. _In the case of threadless headsets, the *stack height also includes the height of the part of the handlebar stem *that clamps to the steerer. _

I guess the phrase _changes saddle to bar drop _or _changes bar height _will suffice unless you (or others) can offer a more appropriate term.


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## Mr. Versatile (Nov 24, 2005)

I wouldn't change a thing. Flip it then ride for awhile - maybe a few days or a week. Your body will tell you what you need to change, if anything.


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## Opus51569 (Jul 21, 2009)

PJ352 said:


> You had a role in this as well, Opus. You provided the example! :thumbsup:


LOL, if by "example" you mean I was the dolt who forgot what I learned in 8th grade geometry about complimentary angles... then, yes, I suppose I had a role. Incidents like that are why I'm glad we don't use real names around here...


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