# Best way to calculate stem length.



## drainyoo (Jul 14, 2007)

Is there some sort of formula that can help me calculate the correct stem length that I would need? Taking into affect the virtual top tube length, my torso length and my arm length. Or is it just trial and error?

By the way here are the measurements on my frame.

Virtual TT - 55cm
Actual TT - 53.8cmm


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## C-40 (Feb 4, 2004)

*no formula..*

There are simple ways to compare an old frame with a new one, but no reliable way to determine stem length by calculation. There are online calculators that will spit out recommendations, but they are worthless, IMO. You'd be as well off to buy a 110mm and start from there.

Even with accurate body dimensions, some people will want the saddle further back than others and that affects the comfortable stem length. Stem length is largely preference. I want mine just long enough that my knees and arms never contact when I'm riding in the hook section of the bars, with my upper back nearly horizontal.

Another thing that can't be calculated is the handlebar height. I use a 9-10cm drop from the saddle to the bars, while others my size only have a 5cm drop. That makes a big difference in the choice of head tube length and stem angle.

The only TT length of value is the horizontal or "virtual" length on a sloping frame.


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## drainyoo (Jul 14, 2007)

Thanks. I guess I can do what you suggested and start with 110 and go from there.


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## samcat (Feb 3, 2004)

*Here's a calculator...*

http://www.habcycles.com/fitting.html

PH


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## jhamlin38 (Oct 29, 2005)

I would start with proper saddle height and knee over peddle position. Its easy to be comfortable and too far back, which can and will sapp power, efficiency and ability to spin. Then consider reach and bar drop, while in drops. If you do the bar drop and stem length measurement on the hoods, you'll find the drops too low and never use that position. 
I just completely changed my setup and I'm far more comfortable and faster than on my previous bike. 
Good luck


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## rkb (Apr 4, 2007)

Its kind of pricey but look into getting a Serotta fitting done. This is a professional fit done on a Serotta fit cycle and with their method of fitting. The system is designed to sell you a custom fit bike but it is also very helpful in fitting your current ride to you. The it process looks at you as a whole by not just measuring you arms and inseam but also determining your core flexibility and assessing your needs, riding style and past injuries. The specialist will take your fit numbers a establish a few points in space that will represent your overall reach, saddle height, and correct bar width and drop. They take these numbers and set your bike up to match. This process is around 150 dollars and can take a few hours to complete. In my opinion this is a worth while process that takes far more into consideration than any online calculator can. In my experience the Serotta fit specialists have a greater understanding of bio-mechanics as they have been through a through training process. And no, I do not work for a LBS that does this, I'm just like you that got tired of trial and error and was looking for a better option.


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