# stem terminology - rise



## tarwheel2 (Jul 7, 2005)

I'm looking for a stem for a new frame and getting very confused about the terminology for stem rise. It doesn't seem to be consistent. But what is consistent in bike components?

So, I understand that a +/-17 stem will provide your bike with the traditional stem that is level or parallel to the top tube (assuming that is level). I also understand that a 90-degree stem will form a right angle. What is confusing to me is all of the variations. Eg, is a +/- 6 stem the same as a 96/84 degree stem? Would a 105-degree stem be the same as a +15 stem?

I am looking for a stem with a moderate amount of rise, about 90-degree or slightly more. So would I be looking for a stem that is +6 to +10?

(BTW most of my bikes until recently had quill stems, hence my confusion.)


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## bikerjulio (Jan 19, 2010)

your understanding is correct. a +/-6deg stem is probably the most common type - ie Ritchey, providing moderate rise.


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## Special Eyes (Feb 2, 2011)

You got part of it correct. A zero rise stem is square to the head tube, and it gives you some rise since the head tube is not true vertical. The common 6 degree stems can add to that for more rise or subtract if inverted. Typically, this will yield a position 11 degrees from true horizontal. Personally, I like my stems to be true horizontal so I use 17 degree stem. It's just arithmetic.


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## tarwheel2 (Jul 7, 2005)

Thanks. What was confusing me was what the +/- was in relationship to. So the standard "zero rise" is 90-degree, and all of the +/- sizes are in relationship to that angle.


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## tarwheel2 (Jul 7, 2005)

Another question. My Salsa Casseroll has a Ritchey stem, probably the Comp model. My bike mechanic and I selected it with me on the bike, and it fits perfect. It has a 12 cm reach (measured center-center) but I'm not sure of the rise. Near the fork clamp, it is stamped "113.06" -- does that mean it's a =/- 6 rise?


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## C-40 (Feb 4, 2004)

*info..*

Stem angles can be expressed from two reference lines - the steering tube centerline, or a line perpendicular to it. The small angles like plus or minus 6 degrees come from the MTB viewpoint. The large angles like 84 or 73 degrees come from the road bike side. 

In the old days of quill stems, nearly all stems were 73 degrees. Subtract a common HTA of 73 degrees and it tells you that the stem is horizontal and has no rise, relative to the ground. Angles greater than that create some additional rise.

A stem angle of 84 (minus 6) degrees is common for Ritchey stem. Of course those can be flipped up to an angle of 96 or plus 6 degrees. In the 84 degree position, you get a rise of about 23mm with a 120mm stem length (sin11 times 120).


A 90 degree or "zero rise" stem would have an angle of about 17 degrees, relative to the ground and a rise of around 35mm. 

Often overlooked is the true horizontal length of the stem. Stem lengths are measured along the centerline of the stem extension, so a 120mm stem with a 90 degree angle actually has a horizontal length of only 115mm.

If you flip and 84 degree stem to 96 degrees, it becomes nearly a full size shorter in horizontal length, so you get more rise and less length at the same time.


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## Kontact (Apr 1, 2011)

C-40 said:


> Often overlooked is the true horizontal length of the stem. Stem lengths are measured along the centerline of the stem extension, so a 120mm stem with a 90 degree angle actually has a horizontal length of only 115mm.
> 
> If you flip and 84 degree stem to 96 degrees, it becomes nearly a full size shorter in horizontal length, so you get more rise and less length at the same time.


Actually, there is no consistant rule for stem length. While many are sized by center to center length, I have at least one 3T threadless that is sized horizontally.

Your second assertion isn't really correct, either. If you flip a typical 100mm +/-6 degree stem the reach changes by 6mm, or about 1 half size. To get a whole size different you either need to be flipping a 150mm stem, or a +/-10 degree.


Here's a nice tool for figuring out reach equivalents with different stems:
Bike Stem Calculator - Brightspoke


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## C-40 (Feb 4, 2004)

*well...*

The 3T brand is an oddball. When they first came out with threadless stems, many people noted that their stems were not the same as most other brands and not the length that they expected to receive, when ordered. The vast majority of brands measure along a line that is parallel to the stem extension and intersects the center of the handlebar clamp.

The horizontal length of a 120mm by 84 degree stem is cos11 times 120 = 117.8mm. Flip the stem to 96 degrees and the length is 110.5mm. The difference is 7.3mm. The point is that the length change is significant and often ignored. Flip an 80 degree stem up to 100 degrees and you get a full size shorter.

Even the calculation above is not 100% correct because it assumes that the centerline of the stem extension intersects the center of the steering tube clamp, which is rarely the case. For that same reason, calculations of the rise or drop from flipping a stem are not perfectly accurate.


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## nhluhr (Sep 9, 2010)

C-40 said:


> The horizontal length of a 120mm by 84 degree stem is *cos11 times 120 = 117.8mm. Flip the stem to 96 degrees and the length is 110.5mm. The difference is 7.3mm. The point is that the length change is significant and often ignored. Flip an 80 degree stem up to 100 degrees and you get a full size shorter.


*Assuming your head tube is 73 degrees. The shallower your angle is (like on a small cyclocross frame), the more reach will be affected by flipping. The steeper it is (like on a tall road race bike), the less reach will be affected.

But just for sake of numbers, lets do the math for a shallow 71.5 head tube all the way to a steep 73.5 headtube:

shallow: flipped: 120*cos12.5 = 117.16 not flipped: 120*cos24.5 = 109.20mm (diff is 7.96mm)

steep: flipped: 120*cos10.5 = 118.00 not flipped: 120*cos22.5 = 110.87mm (diff is 7.13mm)

So you might say _for all typical bikes, flipping a 120mm 6 degree stem will give you a 7 to 8 mm reach difference._ That's pretty damn significant.


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