# Saddle to bar drop calculator?



## tyro (May 15, 2005)

I used to use Bike Forest but then they "upgraded" and removed the facility to calc the bar drop. Any others out there?


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## immerle (Nov 6, 2007)

I don't know anything about handlebar drop calculators or what you would use them for, but don't you measure the top to the bars to the ground and subtract that from the top of the saddle to the ground?


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## jhamlin38 (Oct 29, 2005)

that's how I measure it. if you're trying to determine what drop is proper/recommended for you, which certainly could be argued, I'd go to wrenchscience.com. I've used theirs to setup a bike before, and it was spot on for me....
that said, the fitter I get, the more I tweak my position. I'm planning on dropping my bars in the near future, so the original measurement/drop will be different. 
just use it as a baseline, and modify as you pile on the miles, or see fit...


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## tyro (May 15, 2005)

I guess I should clarify. I'm looking at the geometry on new bikes and trying to calc the saddle to bar drop given my current saddle height from BB to saddle top. You used to be able to enter the geo specs into Bike Forest and then it would show you the bar drop. I'm looking for another calculator to do this.


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## terrain (Apr 19, 2009)

+2 on Wrench chart/setup- I'm happy/comfortable with a setup they did for me.


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## tyro (May 15, 2005)

I guess I'll clarify again. I know and am comfortable with my current bar drop. I am looking at new frames and need a way to calculate the bar drop based upon the geometry of the frame. You input parameters like headtube length and angle, bb drop, seat tube angle, top tube length, etc... and it shows a graphic of what the frame looks like with a way to measure the difference between the bar height and the saddle height.

Does this make sense?


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## AFS (Sep 15, 2004)

Using bikeforest/bikecad’s “handlebar from BB” length (Y) you can calculate handlebar drop:

handlebar drop = (saddle height) x sin(seat tube angle) - Y - (handlebar diameter/2)

Example:









Handlebar drop = 750.0mm x sin(73 degree) -630.6mm – (31.8mm/2) = 70.7mm


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## tyro (May 15, 2005)

AFS said:


> Using bikeforest/bikecad’s “handlebar from BB” length (Y) you can calculate handlebar drop:
> 
> handlebar drop = (saddle height) x sin(seat tube angle) - Y - (handlebar diameter/2)
> 
> ...


Ah! That's what I'm looking for! Thanks so much!


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## C-40 (Feb 4, 2004)

*overthinking....*



tyro said:


> I guess I'll clarify again. I know and am comfortable with my current bar drop. I am looking at new frames and need a way to calculate the bar drop based upon the geometry of the frame. You input parameters like headtube length and angle, bb drop, seat tube angle, top tube length, etc... and it shows a graphic of what the frame looks like with a way to measure the difference between the bar height and the saddle height.
> 
> Does this make sense?


I know exactly what you want, but there is no need for a lot of fancy calculating. Very few frames have a BB height the varies much from the standard 7cm. The only other value worth considering is the head tube length, with the headset. Every brand should list the HTL, but none of them mention the headset stack height. Conventional headsets are 25-35mm in height and integrated are 8-25mm.

All you need to do is be sure that you don't get a total head tube length, with the headset, that is so tall that you can't the bars high enough, or the opposite, so short that it requires too much spacer.

As an example, with my bike, I use a 145mm total stack height - a 125mm head tube, 15mm headset top and 5mm of spacer. With a 73cm saddle height I get a drop in the 11-12cm range, using a 73 degree stem or 9-10 with an 84 degree stem. That's all I need to know to compare some other frame.

Many brands fail to list their fork length and without that, there is always some unknown that could be in 5-10mm range.


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## ktuck (Jul 3, 2008)

per http://spedr.com/4bxnz that's about 1.1 times the width of a U.S. banknote


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## tyro (May 15, 2005)

ktuck said:


> per http://spedr.com/4bxnz that's about 1.1 times the width of a U.S. banknote


That is VERY cool webiste!!!

I have never seen that before.

Thanks so much for sharing. :thumbsup:


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## tyro (May 15, 2005)

deleted


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