# Dropper Post Length Selector Tool



## OneUp (Nov 26, 2013)

We get a lot of requests to help people determine how much drop we can squeeze into their frame.

To help, we've created the following online tool. You just need two measurements and we'll even tell you how we stack up against the other guys.

I hope this community finds it useful.

STEP 1 - Measure Dimension X on your current post. This is your current ride height. The distance should be from the top of the seatpost collar to the middle of your saddle rails.

STEP 2 - Measure Dimension Y by inserting a rigid post or tape measure into your frame until it hits an obstruction.

All measurements are accurate to the best our our ability based on published dimensions of competitive posts. If you notice any errors please contact us.

https://can.oneupcomponents.com/pages/oneup-dropper-post-selector-v2



Cheers,
Jon @ OneUp


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## Trinimon (Aug 6, 2019)

Awesome! Thanks Jon. That'll save a lot of calculating and/or trial and error.


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## Narrowback (Mar 26, 2017)

Thank you!


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## Lone Rager (Dec 13, 2013)

Measuring the bike and doing the additions/subtractions was always easy enough. It was getting the dims for the various seatposts that only ever posed a problem for me. Some manufacturers have nice dwgs with the dims on their sites. Others, not so much.


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## OneUp (Nov 26, 2013)

Lone Rager said:


> Measuring the bike and doing the additions/subtractions was always easy enough. It was getting the dims for the various seatposts that only ever posed a problem for me. Some manufacturers have nice dwgs with the dims on their sites. Others, not so much.


Ha - That doesn't surprise me for someone with the signature "Do the Math" ?.

We were seeing quite a bit of confusion around our shimmed options and the "X + Y ≥ A" of our long hand instructions.


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## Lone Rager (Dec 13, 2013)

Being a Boomer, STEM was the norm before the acronym was invented subsequent to the need to re-emphasis these subjects after the liberal arts focused education that followed. No web based calculators/converters back then. We learned how to do word problems, then translated that skill to practical use in daily life, which nowadays includes things like figuring out dropper post fit.


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## Le Duke (Mar 23, 2009)

Lone Rager said:


> Being a Boomer, STEM was the norm before the acronym was invented subsequent to the need to re-emphasis these subjects after the liberal arts focused education that followed. No web based calculators/converters back then. We learned how to do word problems, then translated that skill to practical use in daily life, which nowadays includes things like figuring out dropper post fit.


You understand that several of the components of STEM are part of the classical/current definition of liberal arts, right?

Sent from my iPhone using Tapatalk


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## Lone Rager (Dec 13, 2013)

Science, Technology, Engineering and Math. Yeah, pure science/math can technically be lumped in with liberal arts, so how would you refer to a curriculum that minimizes these? Back in boomer times, "liberal arts" was a pejorative term for such curricula. 

And, straightforward calculations employing addition, subtraction, multiplication and division were referred to as arithmetic. You weren't doing math until manipulating variables in algebra, trig, geometry....


...get off my lawn!


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## Harold (Dec 23, 2003)

Lone Rager said:


> Measuring the bike and doing the additions/subtractions was always easy enough. It was getting the dims for the various seatposts that only ever posed a problem for me. Some manufacturers have nice dwgs with the dims on their sites. Others, not so much.


This is my experience as well. The answer for me - if the post mfr doesn't supply drawings with dimensions (or supplies incomplete dimensions), then it's crossed off my list.


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## andy f (Jan 13, 2004)

Lone Rager said:


> Science, Technology, Engineering and Math. Yeah, pure science/math can technically be lumped in with liberal arts, so how would you refer to a curriculum that minimizes these? Back in boomer times, "liberal arts" was a pejorative term for such curricula.
> 
> And, straightforward calculations employing addition, subtraction, multiplication and division were referred to as arithmetic. You weren't doing math until manipulating variables in algebra, trig, geometry....
> 
> ...get off my lawn!


Math starts at real analysis. Or abstract algebra, if you swing that way. Not judging.


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## Trinimon (Aug 6, 2019)

While I can do my own math to calculate which dropper length I need, the big plus for this calculator is that it gives me the different brands lengths that will fit, all at the same time. Saves me having to dig up all the insertion and OAL measurements for each one.


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## SkyManatee (Jul 28, 2019)

Thanks, OneUp. This is a nice tool. I do my own calcs but it's nice to have a sanity check when I run into some odd long droppers.


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## j4m3z420 (May 10, 2012)

OneUp said:


> We get a lot of requests to help people determine how much drop we can squeeze into their frame.
> 
> To help, we've created the following online tool. You just need two measurements and we'll even tell you how we stack up against the other guys.
> 
> ...


Does this calculator factor in the actuator at the bottom of most seatposts?


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## OneUp (Nov 26, 2013)

j4m3z420 said:


> Does this calculator factor in the actuator at the bottom of most seatposts?


Yes it does. All fits are based on the Total length including the actuator.

Jon


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## 006_007 (Jan 12, 2004)

Great tool to refer people to.


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## andy f (Jan 13, 2004)

Anyone check the PNW Loam post calculations for accuracy? For X=280mm and Y=200mm, I get a max drop of 200mm for the Loam post vs. 180mm for the OneUp V2 using the calculator Looking at the PNW Loam specs for 200mm drop though, it has a full insertion length of 290mm and a min saddle rails to collar measurement of 250mm for a total length of 540mm. So I would have 340mm exposed above the seat clamp due to my Y=200mm measurement, which would be 60mm too tall. Makes me think they used the dimensions for the 170mm Loam post instead of the 200mm model by mistake.


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## rufus (Jun 15, 2004)

Nice. This just confirmed what I've been trying to settle on the past couple days. Just came from the OneUp website, where I figured that the 180 shimmed down to 160 would be the longest I'd be able to do, and this calculator confirmed. At that point, i don't see why I just wouldn't go with an unshimmed 150. 

150 max for a Fox transfer or KS Lev as well. I wanted to go Fox, but I think I will stick with KS, as a 125 is what I have now. The OneUp and Fox will mean inserting about 12mm deeper into the frame, while the KS will need to go 25mm deeper. So, less exposed post, and all I'd need to do is just swap the saddle to the new post, and hook up the existing cable. No new lever required either.


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