Dropper Post on a Road Bike

Aug 27, 2012
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#1
First up admission is that I am a terrible descender. 5-year-old's on Mama Chari's overtake me coming down Wada.
However I just read an interesting article from the guy behind Sky's aerodynamic body positioning who is experimenting with dropper posts on Road Bikes. Apparently the reason the Pro's (eg Frome on that TdF descent) are moving on to their Top Tubes while descending, is that it lowers their back to reduce air resistance (and also provides a secondary benefit of lowering their centre of gravity). However it is not the safest position being so far forward, so instead he is trying to achieve the same thing with just allowing their seat to drop on descents....
Sadly my Synapse has a 25.4mm seat post so I can't try it out, but if anyone has (i) a dropper post (ii) the ability to fit a dropper post on their road bike (and the seat clearance to drop) would interested to hear if it works for them...
 

saibot

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May 29, 2012
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#2
It would work, but since it's more to descending than just low centre of gravity it wouldn't make a bad descender good just because of a dropper post.
As with dropper posts on MTB's the when in full descending mode cornering, you don't really put any weight on a saddle, the main idea is getting the saddle out of the way so you can get lower without sitting on the saddle.
Working on braking, cornering technique, line choice etc would probably improve your descending more than a dropper post, but it definitely wouldn't hurt.
Would be interesting to try for sure, but the added weight! :eek:

GCN did a video on it a few weeks back I think, not a huge difference in the end but giving it a bit more time and get used to it I'm sure you could have of a few more seconds.
 
Aug 27, 2012
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#3
Good points @saibot - I should have said, I'm not expecting it to compensate for my poor technique - very much working on that separately. Just find the idea very intriguing. Unlike the MTB dropper's intended use which gets the seat entirely out of the way as you said, what was being suggested in the article was to still fully use the seat on the straight sections, just with your whole body now planted lower (and still able to pedal if necessary).
I'll try to find that GCN video.
 
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saibot

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May 29, 2012
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#4
Ah that's true... straights you definitely sit on the saddle, unlike MTB, good point!

Oh, and my comment was more general advice that been passed down to me, not directed at anyone. (should not have used the "You/Your") I think I've ridden with you once or twice and can not remembering you being a snail downhill. Us mere mortals just have to accept not being downhill demons like @Heath or @leicaman :)

I observed people that grown up on skis/snowboards/MTB/motorbikes seem to have a talent for descending even though the technique for each are pretty different. With leads me to believe confidence, ability to read the terrain is a big factor.
 
Aug 27, 2012
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#5
can not remembering you being a snail downhill.
Very kind of you to say
people that grown up on skis/snowboards/MTB/motorbikes seem to have a talent for descending even though the technique for each are pretty different. With leads me to believe confidence, ability to read the terrain is a big factor.
So agree. Having been born in the flat lands near London and not picked up a ski until I was 26, I still thought Greenwich Hill* was a large descent until I came here 4 years ago....

* https://www.strava.com/segments/661573
 

bloaker

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Nov 14, 2011
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#6
MTB Droppers range from 75mm to 150mm drops. Add the room for the collar at the bottom and the head and you are talking about another 50mm+
If you have less than 125mm of seatpost showing - a dropper just isn't going to work anyway.
Then think of all the money wasted to get a bike a couple of grams lighter, just to add 592 grams (for the thomson) for the occasional need to lower it.
I have a few droppers on my MTBs - and while they are great at times - they could easily be replaced with a few seconds of time and an alan key.
 
Aug 27, 2012
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#7
Great info @bloaker - didn't realise about the collar height, but makes perfect sense given the current design of them. Also the weight is significant (perhaps unsurprisingly).

Thinking I might have to design one then....
  • Uses standard seat post with QR seat post bolt on the frame rather than standard nut/bolt
  • Lightweight Spring that is compressed when seatpost QR is slackened and seatpost drops due to rider sitting on it. Tighten QR
  • Descend
  • Rider removes self from seat; slacken off Seatpost QR, spring returns seat to top; tighten QR.
Obviously need to find a way (i) for seat to only rise to your preset height (ii) seat to remain straight (iii) friction interface to be enough that seat doesn't move when QR is tight, but not enough friction for post to move easily when QR is open......hmmmmmmmm ...might explain why Sky don't already have this on their bikes.:D
 

bloaker

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#11
Seems that is the minority of frames still.
This style would make more sense, no need for cables or a remote. - the lever is under the nose of the saddle.

Again - fun to speculate - however I find it to be more or less useless on a road bike.
Even on descents like Yabitsu, there are moments you should be pedaling to keep up your speed.
If your saddle is dropped, you will not be very efficient at all. IMO, you lose more than you gain.

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