# What is a dropper post with the shortest base?



## RU4REAL (Dec 30, 2008)

Hi:
Looking for a dropper post with the shortest possible base - 
"Base" defined as the bottom of the dropper post till the collar, like so:









Issue I am trying to solve is that the existing dropper post on my wife's bike wont go all the way down the seat tube because of a kink/angle in the frame's seat tube. The collar of the droppar currently sticks out 1.5" from the seat tube, preventing the seat from dropping as low as possible to the seat tube.

The current "base" measurement is 7.5" (190mm) and I need one that has a base in the 5.5"-6.0" (140-150mm) range in order to reclaim the 1.5" of drop that is lost due to the kink/angle in the frame.










Thanks
T


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## RU4REAL (Dec 30, 2008)

Forgot to add that the existing deopper is a 31.6x360mm


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## RS VR6 (Mar 29, 2007)

OneUp has a "V2" dropper coming out...and with adjustable extension...it might work for your application. If you scroll to the bottom...there are various length measurements.

https://www.oneupcomponents.com/collections/dropper-posts/products/dropper-post-v2


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## RU4REAL (Dec 30, 2008)

RS VR6 said:


> OneUp has a "V2" dropper coming out...and with adjustable extension...it might work for your application. If you scroll to the bottom...there are various length measurements.
> 
> https://www.oneupcomponents.com/collections/dropper-posts/products/dropper-post-v2


Thanks for the info, looks like that dropper will have a 207mm base (i've since learned the proper term is "max insertion length").

I found an excellent spreadsheet of dropper posts measurements on the web, and it looks like KS has some very short "base" models in the 155mm range (but with 80-100mm travel only).


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## ninjichor (Jul 12, 2018)

I looked, but couldn't really find anything with 150ish max insertion that had 125mm travel or more. Just seems that the post needs that much overlap (50-75mm between the upper and lower bushings) with the inner tube at full extension for structural reasons.

Examples:
9.8 Fall Line R with 125mm travel, and 190mm of post below the collar (internally routed)
Vecnum MoveLoc XC with 100mm travel and 175mm of post (cut) (ext routed)

Hopefully this explains why you might be asking for the unrealistic:









What you are trying to ask for, is a post where the inner tube doesn't extend this far into the outer tube. Engineering challenge that's beyond me...


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## Harold (Dec 23, 2003)

I have a frame with 190mm of possible insertion before a bend in the seat tube, but I need enough exposed post at full extension that to accommodate the full dimensions, the best solution available to me to achieve the maximum drop was to use a 150mm Oneup post (V1), and shim the travel down to about 143mm. It's just plain impossible for me to get a dropper post with the collar slammed AND to be the correct length at full extension on the frame I have.

So, my seatpost collar is a decent bit above the seatpost clamp on the frame. It is what it is.


0404191452 by Nate, on Flickr


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## Shadow4eva (Jul 11, 2017)

What about the BikeYoke Revive? I seem to recall that it has one of the shortest max insertion length.


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## Harold (Dec 23, 2003)

Shadow4eva said:


> What about the BikeYoke Revive? I seem to recall that it has one of the shortest max insertion length.
> 
> Sent from my iPhone using Tapatalk


The Revive 160 falls right between the Oneup 150 and the 170. So it seems to fall in line with Oneup's (v1) dimensions pretty closely (max insert relative to drop).

I think what sets the Oneup apart is the ability to reduce the amount of drop so you can fine tune it to fit the bike. Of course, with the V1, you only have the 150 and 160 to choose from. But in looking at the numbers, it also appears that the Oneup V2 post is a hair longer than v1 (in the max insert dimension). At this point, I'm glad I snagged a v1 because the v2 would not give me as much drop in my situation.

So it looks like the Revive actually has a shorter max insert than the v2 Oneup post. Just no ability to customize/shorten the amount of drop.


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## Shadow4eva (Jul 11, 2017)

Harold said:


> So it looks like the Revive actually has a shorter max insert than the v2 Oneup post. Just no ability to customize/shorten the amount of drop.


I recall there being a thread whereby some guy managed to shorten the travel of other brand dropper posts using the same (or fabricated an identical) plastic shim as the OneUp one. Maybe it can work for the Revive as well?

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## majorjake (Sep 5, 2017)

Harold said:


> The Revive 160 falls right between the Oneup 150 and the 170. So it seems to fall in line with Oneup's (v1) dimensions pretty closely (max insert relative to drop).
> 
> I think what sets the Oneup apart is the ability to reduce the amount of drop so you can fine tune it to fit the bike. Of course, with the V1, you only have the 150 and 160 to choose from. But in looking at the numbers, it also appears that the Oneup V2 post is a hair longer than v1 (in the max insert dimension). At this point, I'm glad I snagged a v1 because the v2 would not give me as much drop in my situation.
> 
> So it looks like the Revive actually has a shorter max insert than the v2 Oneup post. Just no ability to customize/shorten the amount of drop.


The 150mm OneUp V1 has a max insertion legnth of 255mm
The 150mm OneUp V2 has a max insertion legnth of 237mm
The 180mm OneUp V2 has a max insertion legnth of 267mm
The 160mm BY Revive has a max insertion legnth of 264mm

If you want 150mm, the 150mm OneUp V2 is the shortest post
If you want 160mm, the 160mm BY Revive is the shortest post, by 3mm, and without any adjustability.

To me, the OneUP V2 has the best of both worlds, short max insertion, and the ability to adjust the post down to your ideal legnth.


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## Harold (Dec 23, 2003)

majorjake said:


> The 150mm OneUp V1 has a max insertion legnth of 255mm
> The 150mm OneUp V2 has a max insertion legnth of 237mm


To be clear, you're adding the actuator length. I don't care about the actuator length (mostly, at least in my current case).

Here is what I see:

https://www.oneupcomponents.com/products/dropper-post
https://www.oneupcomponents.com/collections/dropper-posts/products/dropper-post-v2

When I first saw the numbers, I did not see the difference in actuator length. I think oneup has added more details since my last posts.

V1 actuator is 32mm. v2 actuator is 15mm.

Max insertion:
V1 150mm no actuator - 223mm
v2 150mm no actuator - 222mm

So there's effectively no difference there. For overall length, the V2 post appears to be 5mm shorter, which looks to come from a shorter collar.

That said, the difference in my case is effectively not useful. v1 post allowed heavily customizable shims to change drop from basically 1mm to 50mm. v2 allows for 10mm or 20mm drop reduction only. I have had to change the drop on mine from what I had before. Seat was too high with previous setting, so I've reduced the drop. IF the v2 post allowed for the same adjustment, I could potentially get 5mm more drop out of it. But it doesn't. So I'd probably have to deal with a little less drop than is maximally possible on my frame.


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## jon_ssss (Feb 20, 2009)

-removed-


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## OneUp (Nov 26, 2013)

Harold said:


> The Revive 160 falls right between the Oneup 150 and the 170. So it seems to fall in line with Oneup's (v1) dimensions pretty closely (max insert relative to drop).
> 
> I think what sets the Oneup apart is the ability to reduce the amount of drop so you can fine tune it to fit the bike. Of course, with the V1, you only have the 150 and 160 to choose from. But in looking at the numbers, it also appears that the Oneup V2 post is a hair longer than v1 (in the max insert dimension). At this point, I'm glad I snagged a v1 because the v2 would not give me as much drop in my situation.
> 
> So it looks like the Revive actually has a shorter max insert than the v2 Oneup post. Just no ability to customize/shorten the amount of drop.





majorjake said:


> The 150mm OneUp V1 has a max insertion legnth of 255mm
> The 150mm OneUp V2 has a max insertion legnth of 237mm
> The 180mm OneUp V2 has a max insertion legnth of 267mm
> The 160mm BY Revive has a max insertion legnth of 264mm
> ...


The thing to remember here is that insertion is a bit irrelevant compared to total length and stack height.

@Harold, The total length of our 150mm V1 shimmed to 143mm is 25mm longer than our V2 at a full 150mm. For a given saddle height the 150mm V2 post will be inserted into your frame 25mm less than the V1 at 143mm.

@MajorJake The total length of our 180mm post shimmed to 160mm is still 6mm shorter than a Bike yoke 160mm. For a given saddle height our 180mm post shimmed to 160mm will be inserted into your frame 6mm less than the Bike Yoke 160.


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## Lone Rager (Dec 13, 2013)

The new Reverb C1 has significantly shorter overall lengths, travel up to 200mm, a purge valve (similar to Bikeyoke Revive) as well as other improvements. Still a stupid a hydro remote though. Early Reverbs were pretty problematic. B1s have been pretty good. Mine has been trouble free for 2 years. Third (fourth?) time's a charm?


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## Harold (Dec 23, 2003)

OneUp said:


> The thing to remember here is that insertion is a bit irrelevant compared to total length and stack height.
> 
> @Harold, The total length of our 150mm V1 shimmed to 143mm is 25mm longer than our V2 at a full 150mm. For a given saddle height the 150mm V2 post will be inserted into your frame 25mm less than the V1 at 143mm.


Except when it matters.

My frame is reamed to a depth of 190mm. I cannot insert a seatpost any deeper. The length of the actuator doesn't matter, so long as whatever actuator fits. The longer actuator of your v1 post fits in my frame beyond that 190mm depth, so it's an irrelevant dimension for my case (and probably a lot of cases) and can be ignored/eliminated from the discussion.

The difference in stack height between your v1 and v2 posts is only 4mm (v2 being a touch shorter) and total length (minus actuator) is 5mm. The choice for me is not between 143mm and 150mm drop but rather between 143mm and 140mm drop. And also the fact that I already own a v1 for this bike.


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## shredjesse (Oct 18, 2017)

I've run into this problem now TWICE on small framed bikes for ladies I've dated over the last few years The issue also occurs on small mens bike frames, so it's not just overlooking women, it's just bad design/work/qa/whatever!

A Transition Patrol, and now a Haibike both have 140mm max insert depth. So a dropper with 220cm of insert depth has 80cm sticking out, plus the nut/seal at 33mm or so, and then 125 mm of drop on most "short" posts. So we're looking at 238mm ontop of the frame. I'm 5'10" and I can't even get on either of these frames at full extension and even dropped it's a bit much for the ladies it was intended for.

Not sure what the industry is up to, but they keep mucking up bikes in the smaller sizes!


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## shredjesse (Oct 18, 2017)

So I found a solution!

The Brand-x Ascend 85mm dropper. 27.2mm diameter. Get that and an adapter sleeve for $10 from cane creek and you're in business!

The jist is that most droppers have 200-230mm of insert, and then 100-175mm of rise. If you're a shorter person... none of that is terribly useful to you, and the frames can't take nearly that length due to the suspension pivots and what not.

The haibike my Fiance got only had 150mm of insert! Well lucky us, the Brand X acend has pretty much that for insert. While 85mm of drop may not be all that awesome for the cool kids beating off over specs... it's just right for my 5'4" fiance to get all the drop she needs and get the ideal seat position on a frame with engineering limitations.


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## OneUp (Nov 26, 2013)

shredjesse said:


> So I found a solution!
> 
> The Brand-x Ascend 85mm dropper. 27.2mm diameter. Get that and an adapter sleeve for $10 from cane creek and you're in business!
> 
> ...


Curious what the length on that post is. Our 120mm (shimmed to 100mm) has a length without actuator of 345mm (325mm). The CRC website shows 350mm for the 85mm post.

*edit - Found the length details below

85mm drop Brand X Ascend
Collar to rail - 155mm
Length w/o actuator - 316.5
Length w/ Actuator - 350mm

120mm (shimmed to 100mm) OneUp V2
Collar to rail - 153mm (133mm)
Length w/o actuator - 345mm (325mm)
Length w/ Actuator - 360mm (340mm)

Jon


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## shredjesse (Oct 18, 2017)

I think approaching the math is incorrect. Here's the math I did, that worked for us and gave us results that matched our measured needs.
















That's the oneup numbers. See measurement F.You take that and subtract the denoted 15mm for the actuator.

So on the 120/100mm OneUp dropper you mention, F is 207mm, minus 15mm. 192mm of insert length minus actuator. Pretty good compared to most of the competition, but only by 20mm or so over my recalled average of around 220mm on most. So less than an inch.









Here's the Brand-x specs. They have A+2 for "insert length", which You then subtract 35mm for the actuator.

The 85mm Brand-X is 195mm, less 35mm... so 160mm of insert length less actuator. That's 60mm less insert length than my recalled average of 220mm. That's over two inches shorter.


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## shredjesse (Oct 18, 2017)




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## OneUp (Nov 26, 2013)

shredjesse said:


> I think approaching the math is incorrect. Here's the math I did, that worked for us and gave us results that matched our measured needs.


I'm stoked you got a solution that worked for you.

I'm only chiming in because I think looking at the insertion in a vacuum is a common mistake. IMHO the dimensions that matter in 99% of cases are extended stack B from our chart (Collar to rail) and either Length A or E depending on whether your insertion is restricted by the actuator or the post.

For simplicity I'll only consider our 120mm post when shimmed to 100mm and assume that you are only restricted by the post (not the actuator).

Proper saddle height for pedaling is a constant. Your photos show the Brand-X post fully inserted. That means that your proper saddle height must be 155mm (the collar to rail distance of the Brand-X post). The collar to rail distance of the OneUp V2 100mm post is 133mm. That means that to achieve your proper saddle height the OneUp V2 would be 22mm higher than fully slammed. Yes our lower tube is longer (192mm) but only 170mm of it needs to be inserted into the frame to achieve the proper saddle height (versus 161.5mm of the Brand-X). Maybe that extra 8.5mm of required insertion is a deal breaker, I'm just trying to illustrate that the difference isn't the 32mm you outlined above.

In addition IF the actuator is an issue The OneUp V2 100mm post would be inserted 10mm less than the Brand-X 85mm post.

I hope this helps the community.

Jon @ OneUp.


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## Smashius Jones (Jun 15, 2019)

This is precisely what the issue is for some short people. While the pedal height is constant, the fully slammed seat and still not being able to touch the ground is the concern. 

So in your diagram, the F measurement is unable to be fully inserted into the frame. For example on my wife's Trance, there seems to be only 150mm of room for a post to be inserted before running into the suspension/bend in the frame. What is needed in her particular case is a dropper with ~150mm max insertion to set the seat lower when dropped, but still 100-120mm of travel for proper pedaling. I haven't found the solution for this exactly, but am open to suggestions...?


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## shredjesse (Oct 18, 2017)

That's roughly where my fiance was at. 150mm of insert was the most we could get, she needed 120mm of rise or so from the top of the seat tube. With the collar adding 28mm, and the rise of the seat at 85mm, we're pretty much right in the vicinity for ourselves, and it sounds like just what you need.


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## Andrie (Jun 5, 2020)

I’m in the same boat looking for short seat post when collapse. Initially shredjesse post make sense but then I selves into it further and realized the important thing is not the insertion rather the total length while collapse. In this case the one up is actually shorter when collapse. Even though it has 120mm travel compared to brand x 85mm travel. 

so here I am still looking for solution for short people. If anyone realize there is a market for it, my wife would be really happy.


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## ckisela (Jan 29, 2021)

I stumbled across this post after searching for a replacement dropper for my Specialized stumpy. I'm short with a small frame and am getting the same problem with my dropper bottoming out before it hits the collar. It seems as though I only have about 6 1/2 inches of max insertion length yet most droppers are around 8 in before any linkage.
Right now in my search, the best dropper I've found is the Brand-X Ascend II Dropper Seatpost which has a maximum insert of 128 mm...however this is an external dropper, so not much luck finding something internal yet.


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## Aglo (Dec 16, 2014)

Currently OneUp droppers are the ones with the lowest stack height, followed close by BikeYoke droppers. Regarding insertion length for the same travel length, if I recall correctly, they are both around the same. But they have different travel length, which will give you the option to get a post to best suit your needs.


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## ckisela (Jan 29, 2021)

The BikeYoke Divine looks promising with a 145mm insertion when cutting the bottom.








Where the OneUp Seems to be at 207mm (D)








Or for half the price, the KS Rage-I (D)


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## CRD_315 (Jun 1, 2021)

Did you go with the Brand X Ascend CX, and then shim from 27.2 to 31.6? We got a diamond back Clutch that my son is riding and are having the same issue.


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## CRD_315 (Jun 1, 2021)

found this list which lists a ton of post lengths Dropper Seatposts


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## samuraisd (8 mo ago)

Fast forward to 2022, we now have OneUp V2 90mm, with insertion length 167-15 mm= 152mm, which is about 6" of insertion, however, 90mm is a bit low of an extension. About 3.5", I can ride a bit better to 4", which is 100mm. However, there does not seem to have a dropper post with this specs; a 152~mm insertion, with a 100mm dropper height. I guess 90mm will do but OneUp V2 is so out of stock now for a few months. Anyone knows other brands that are closed to this 100mm? I've researched KS-LEV, 155 mm insertion, but 80mm dropper height, a bit low. KS Rage-i has rather good insertion length, 161mm but 75mm, I think both are about the same, Rage-i will always sticks out a bit plus the collar and then extend < 3". Where the LEV insertion is 3mm sticking out, but only 80mm ~ 3". So OneUp V2 90mm + collar might be just right.


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