# How to select stem size?



## notwist

I currently have a 90mm stem but I want to get a more "aggressive" fit by lowering the handlebars and increasing the reach. How do I know which size stem I should get? Should I just go 10mm longer and get a 100mm?


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## CleavesF

Stem size is done after you've been fitted to your crank with your saddle position. 

It is best to start with a ghetto adjustable stem if you're not sure how much reach you want permanently. Get a value adjustable stem for ~30-60 bucks, and then tweak to find your optimal setting, then buy a nice permanent stem size and leave it be.


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## Marc

Slow down thee grasshopper. A 90mm stem, in the 1st case, is indicative of a poor fit. Also a 90mm stem will alter the steering properties of your bike

Also, stem length is not the only factor, there is also angle. There are lots of things going on here that need to interact right for you to be comfortable on the bike. There is reach, there's saddle/bar drop, and there is also how flexible you are.


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## PJ352

notwist said:


> I currently have a 90mm stem but I want to get a more "aggressive" fit by lowering the handlebars and increasing the reach. How do I know which size stem I should get? Should I just go 10mm longer and get a 100mm?


I think you're somewhat blurring the lines between reach and "aggressive (lower) position". Going from a 90 to 100 mm stem and not changing the angle is simply increasing your reach by 10 mm's. It'll drop the bars, but minimally. 

Going to a more aggressive/ lower position is changing what's called stack height, so if you're otherwise comfortable on your bike, but wish to go lower, then you'd _only_ change the _angle_ of the stem. So if you tell us what your current angle is (I'm guessing about a -6 degree - meaning it's flipped down) and size and number of spacers below the stem, we can give you some options.


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## notwist

The LBS fitted me to my bike when I first bought it so I don't plan on changing the saddle position. I have since put on about ~1500 miles and removed 2 spacers lowering my handlebars 10mm but I wish to get into a more aggressive (lower) position. Yes, the current stem I have on my bike is a 90mm, -6 degree with a single 10mm spacer left between the stem and the headset. Any ideas?


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## Marc

notwist said:


> The LBS fitted me to my bike when I first bought it so I don't plan on changing the saddle position. I have since put on about ~1500 miles and removed 2 spacers lowering my handlebars 10mm but I wish to get into a more aggressive (lower) position. Yes, the current stem I have on my bike is a 90mm, -6 degree with a single 10mm spacer left between the stem and the headset. Any ideas?


How much drop is there from the top of the nose of the saddle to the drop of the handlebars right now.

It sounds like the bike you have now may be too big for you. A 90mm stem is a sub-sub-optimal solution to a fit problem.


About all that is left is to buy an -10 degree stem, and remove that last spacer.


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## notwist

A -10 degree, 90mm stem ?


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## PJ352

notwist said:


> The LBS fitted me to my bike when I first bought it so I don't plan on changing the saddle position. I have since put on about ~1500 miles and removed 2 spacers lowering my handlebars 10mm but I wish to get into a more aggressive (lower) position. Yes, the current stem I have on my bike is a 90mm, -6 degree with a single 10mm spacer left between the stem and the headset. Any ideas?


You've got two options, but I wouldn't do them both. One or the other.

As Marc suggested, remove the last spacer. Obviously that gets you a 10 mm drop. The other option is to leave the spacer in place and go to either a -8 or -10 stem. This will drop the bars about 5 mm's or 10 mm's, respectively. I err on the side of caution and am frugal, so I'd replace the 10 mm spacer with a 5 mm and leave the stem as is. Second option, I'd leave the 10 mm spacer and go with a -8 stem. Both result in about a 5 mm drop. 

BTW, there is nothing at all wrong with running a 90 mm stem. It won't negatively affect fit or handling one iota. And some bikes come equipped with them.


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## Marc

notwist said:


> A -10 degree, 90mm stem ?



Presuming that your reach on your present bike is so short to warrant a 90mm stem-I suppose. I don't know how you are positioned on your bike, or what frame size you ride, or your personal body measurements/proportions.

A 90mm stem is not good for steering/handling...and usually, unless someone is so lopsided in their proportions, someone is better served by getting the next size smaller bike....rather than needing to use the shortest stem possible, with the biggest angle possible, with only a 1mm headset spacer above the headset.


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## PJ352

notwist said:


> A -10 degree, 90mm stem ?


Here's the equivalent in the Specialized system (12 degree w/ shims).
http://www.specialized.com/us/en/bc/SBCEqProduct.jsp?spid=41848


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## Marc

PJ352 said:


> BTW, there is nothing at all wrong with running a 90 mm stem. It won't negatively affect fit or handling one iota. And some bikes come equipped with them.


Well, I will say some bikes come equipped with them...but...unless you're riding a 40cm frame-I wouldn't expect to find one much.

You're altering your stem length by ~20% from say a 110mm. Now your stem/Handlebar is an elaborate lever-arm assembly through which force is applied and countered--I refer you to Newtonian physics to deduce my conclusions regarding how much difference there is in play from here.


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## PJ352

Marc said:


> Well, I will say some bikes come equipped with them...but...unless you're riding a 40cm frame-I wouldn't expect to find one much.


Really? Click on the geo tab, then check out the stem lengths for a 49 and 52 cm.
http://www.specialized.com/us/en/bc/SBCBkModel.jsp?arc=2008&sid=08Allez
Then call Specialized and tell them they're putting riders in dire risk.  



Marc said:


> You're altering your stem length by ~20% from say a 110mm. Now your stem/Handlebar is an elaborate lever-arm assembly through which force is applied and countered--I refer you to Newtonian physics to deduce my conclusions regarding how much difference there is in play from here.


I'm thinking you don't ride motorcycles much.  It's not a lever/ arm assembly that you _turn_, you _push_ outwards with the opposite hand/ arm that you want to turn. Make a left? Push out with right.

May be an incorrect analogy, but I think of the front wheel as a gyroscope and the bars as part of the linkage allowing for change in angular momentum.


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## Zachariah

If the OP wants to fully extend their arms for the sake of "aggressive pro fit" ...they are smoking bad idea weed. With elbows fully locked- you're gonna feel all the load placed on your head and neck...especially after a 40-miler.


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## martinrjensen

*I didn't see it mentioned*

but can you flip the stem? Threadless stems should be able to be removed and flipped so that would put the bars lower. Unless of course you already flipped it. I don't think you said which way it was.


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