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this person is new to folders, English is not theyr main language and they are a teacher- used to speak , not listen. Have patience, we are slowly getting there. Go play with your bikes if it is hurting to hang around here... :thumb:

Hi again..

I am having trouble finding a correct seatpost to my bike.

The current seatpost is 400mm

My inner leg distance is 870mm

Can someone tell me what seatpost length should I get?

I talked with a guy that messes with alluminum and steel in order to make me a seatpost tube but then don't know if it will fit the saddle...

Any help...

What is the bike's seat tube length?

Crank-arm length + seat-tube length + seatpost insert length + saddle rails-to-seat distance = 820mm (as a first approximation

Here are the measurements of my bike... See the attached image.

Diameter of seatpost= 31.8mm
Height of seatpost=400mm

To measure the seatpost you need to pull it out of the bike completely and measure it.

More important than lenght is actually how wide it is, the diameter. If it is not exactely the right size you`ll not be able to sit on it.

take a look at what I said about using a telescopic seatpost but first of all you need to properly mesure the one you have.

https://www.ebay.com/sch/Sporting-Go...p2045573.m1684

1.25" 31.75 mm is a common diameter for folding bike seatposts, it's stiffer as the tube is bigger, and folding bikes have rather long ones.

measure diameter

How Long? Depends on your saddle height, that is generally....

sitting on the saddle, leg straight, with the heel of your foot on the pedal (flat sole shoe, not much heel on shoe,

then you measure that distance... too..



...

2 pictures of my 2 Dahon Boardwalks with aftermarket seat posts. They are longer, lighter and stronger than the factory steel seat post. E-Bay bought for less than $25 shipped. I am 6 feet tall mine are not quite fully extended. 31.8 diameter. Roger

Are your handlebars/stem on these bikes stock?

Hi Roger,

Do you have link of the eBay seller store? Or link of the seatpost?

Also what's the height of those seatpost?

The diameter of my seatpost is 31.8 mm and.is 400mm long.. so too short for me... And it's steel a bit heavy.

Stock non adjustable stem and handle bars. The only change is I added two 10-24 threaded nutserts to mount a water bottle cages (see pictures). Found the seat post looking up Dahon parts on E-Bay. I think the seller was from New Jersey but don't have a name for the store. Bars name is Lite Pro and comes in 4 colors but generally they only have 1 or 2 colors in stock. Lite Pro also produces cranksets with large tooth count sprocket. Basically they make folder parts. I like the way the seats are clamped on the seat posts but it takes a bit of time to adjust them. Once adjusted they stay adjusted. When I look for things on E-Bay I generally add USA only to my searches. Not sure about the post length but the say it in the ads. Roger

Dahon seatposts have a diameter of 33.9mm and not 31.8mm as you wrote in your previous post. Lite Pro seatpost are sold with Dahons diameter.

Iam looking for a 31.8mm X 600mm seatpost black.and it's hard because my saddle has a different connection clip to the seatpost...

Generally there are two type of seatpost.
They fit pretty much any seat.
Either the seatpost has a built in clamp like the one shown in your picture.

Or it has no clamp but tappers to a 25.4mm end. If it's simply a straight pipe without a clamp type seatpost you just need to add a seat clamp to the seat. They cost about £.

Ok

A thread in the past was about ordering a custom Titanium version of the Xooter Swift.. direct from China.

Some Dahons, like my Dash and Dash Altena, take 31.6mm. Very long and 31.8mm is unusual.

Yes you are correct those posts are 33.8 at least that is what my cheap micrometer says. Sorry about that. Roger

Hmmm,...you told us to be nice, then you post a video of a CHILD instructing someone how to change 2 types of bicycle seat.
NOW, that's actually NOT NICE. It looks like sarcasm,...hmmm:lol:

I know, I was thinking the same but the fact is it was the only good film about the topic. I did not want to spend hours looking for blogs or similar and a film is always best when you want to learn something new :thumb:

Not really, just in the Dahon universe. 31.8 is what i.e. the Brompton uses and there are more than 500.000 out there. Seat posts with this diameter are available from Brompton as well as a huge amount of 3rd party suppliers in steel, aluminum, titanium and carbon from cheap to very expensive. 600mm is a standard length on the Brompton - it is called the extended seat-post. You get it in this length from a Brompton-shop in steel or i.e. a cheap titanium or carbon post from China via ebay or a aluminium one with built in rear lights from Lightskin. Or you look at the various Brompton tuning shops on the net if you are willing to spend more money.

i actually own two Dahons, three Bannards, a FnHon, two custom bambu jobs, and a FSIR, and a Surly is on order so I am not speaking from a Dahon universe. In the universe of bicycles are 31.8mm seatposts rare? What's half a million Bromptons against the wide range of bikes and the common seatpost sizes? On the Chain Reaction, for example, 31.8mm shows one item, a shim. 31.8 is closer to rare than commonplace, and speaks to the more 'specialized' sizes and parts of the Brompton bicycle.

Well, you are the guy that constantly complains about the ignorance of people that do not think of the specialities of indonesia when posting to this forum. Now you do the same thing: Something you don't know must be silly, otherwise you would now it. Just because you do not own something or do not know something that does not mean it would be rare, strange or useless... According to the dictionary:

https://en.oxforddictionaries.com/definition/rare

I would not consider something "rare" if it exists in 500.000 pieces from Brompton alone plus the numbers from other manufacturers plus the aftermarket brands. It it not a collecter's item - just an ordinary piece of equipment like many others. And there are a lot of bikes or bike parts that are rarer - i.e. probably your Bannard... But does this make it a useless or strange bike? And what are "common seat post sizes"? Who defines them? You?

APB/TSR Moultons over the past 20 years have 31.8mm seatposts .. the newest SST is 31.6

I was only messing with you,...LoL!!! :P