from Rookie’s keyboard,
Hello, friends
What’s up? Let’s hope the new week brings us something positive (or at least progressive.)
Today, I will make a short post simply to depict one instance when dropper posts are simply pointless – on dirt jumpers.
Technically, you can install one, but at the end of the day, those bikes have another purpose.
Their geometry (and sometimes seat tube shape) just don’t agree with long seat posts.
No one is stopping to do this mod. Keep in mind the following if you have similar plans:
- You Need a Dropper Post of a Very Specific Size
The diameter of the dropper post should be compatible with the seat tube of the dirt jumper. Otherwise, the dropper post won’t fit in or will wobble around.
To learn what size dropper post you need, take out the default seat post and check the reading on it. More often than not, DJs use 30.9mm or 31.6mm seat posts.
The above sizes are for dirt jumpers with wide aluminum tubing. Dirt jumpers with steel frames have thinner tubes and in some cases, many need a slimmer dropper post.
Thinner dropper posts are hard to find because the entire dropper post family targets the MTB segment where aluminum and carbon dominate as frame materials.
- The Right Length
The dropper post should be long enough to provide a comfortable pedaling position. This is a BIG issue because dirt jumpers have small frames and short seat tubes. Consequently, tall riders need a significant rise to sit and pedal comfortably.
To find out how long the dropper post should be, you can use the following guideline:
- Extend the current seat post to the point where it allows you to assume a somewhat comfortable position.
You may have to pull the seat post above the point of minimum insertion – a measurement designed to prevent excessive stress on the seat tube and the seat post.
Since the purpose of this procedure is only to determine the needed length of the future dropper post, the practice is acceptable.
- Measure the seat post section above the seat collar. The new dropper has to provide the same height.
The total length of the dropper post minus the minimum insertion length will have to be equal to or greater than the seat post length needed for comfortable pedaling.
For instance, if the total length of the dropper is 530mm and its minimum insertion depth is 150mm, you are left with 380mm of usable length.
If the length is within that number, the dropper will elevate you sufficiently.
Many Possible Problems
- A Super Short and/or Curved Seat Tube
If the bike has a very short and/or curved seat tube, you may fail to insert the seat post to the required length. In that scenario, you will be unable to lower the seat post as necessary.
- Extra Cables Complicating Tricks
Many dirt jumpers come without a front brake because it makes the execution of certain tricks (e.g., bar spins) impossible.
The cable controlling the dropper will complicate the performance of such stunts too.
This problem can be circumvented by using a dropper post controlled by a lever under the seat. Of course, by going this route, you will be sacrificing comfort and efficiency.
- Unplanned Activation of the Dropper Post (that would be “fun”)
In extreme cases, you may activate the dropper post unwillingly.
And that could be quite dangerous. If the dropper post elevates itself without you realizing, an accident may occur upon landing a trick.
Why?
As the title says – I personally do not see the point of this for most people, and especially dedicated jump riders.
That said, if I had to think of one reason to advocate for this, it would be to versatility.
By lowering the seat, you will be able to perform jumps and tricks such as bunny hops and manuals.
By elevating it, you will have the opportunity to pedal in a seated position – a luxury that dirt jumpers do not offer by default because they’re designed to be ridden with a slammed seat.
It’s questionable whether this conversion will be very effective because the entire geometry of dirt jumpers makes it difficult to pedal comfortably and efficiently.
Below is a list of characteristics that render dirt jumpers poor commuters and MTBs:
- Excessively short chainstays
- Short wheelbase
- Saddle far behind the bottom bracket (inefficient pedaling)
- Excessively upright position creating lots of drag
- Small frame
- Lack of eyelets for water bottles, fenders…etc.
- Shocks designed to absorb massive landings rather than road irregularities
…etc.
K.I.S.S.
Have you hear of the KISS principle. It stands for “keep it simple stupid”. This is one of the instances when we can apply it.
If you plan on using a dirt jumper for commuting and jumping, the cheapest and simplest solution is to get an extra-long regular seat post and a quick-release seat post lever.
Then, you can simply lower the seat post before a session and lift it back for pedaling by opening and closing the quick-release.
Until next time, friends
Rookie
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