My Brompton seatpost is too long.

[Yellow Fang]

I bought an A-type Brompton several years ago. That's the relatively cheap one with no folding pedals ot mudguards. Unlike my previous Brompton L3, when I pull out the seatpost to the full extension, I can't sit on it. I assume this is the longer seatpost for six footers. I was going to order a standard length seatpost, but today I had a look at the bottom of my seatpost to see if there would be any problem swapping the seatposts over. There's a plastic butt at the bottom of the post. Is there anything preventing me from sawing a few inches off the bottom of the post, and swapping the plastic butt over? I have a hacksaw. I also have a circular saw, but I am a little wary of using it in case I saw a hand off.

 

[Kevberlin]

Surely, if you need the seatpost to be shorter, don’t pull it out to its full extension.
There is a small plastic insert available to set the height at a specific height too.
Or, have I misunderstood your issue?

 

[MontyVeda]

I bought an A-type Brompton several years ago. That's the relatively cheap one with no folding pedals ot mudguards. Unlike my previous Brompton L3, when I pull out the seatpost to the full extension, I can't sit on it. I assume this is the longer seatpost for six footers. I was going to order a standard length seatpost, but today I had a look at the bottom of my seatpost to see if there would be any problem swapping the seatposts over. There's a plastic butt at the bottom of the post. Is there anything preventing me from sawing a few inches off the bottom of the post, and swapping the plastic butt over? I have a hacksaw. I also have a circular saw, but I am a little wary of using it in case I saw a hand off.

to remove and swap the seat post you remove the saddle and slide the post out from the bottom end. No need to cut anything.

I have a standard chrome seat post you can have for free (you pay postage). Pm me if interested.

 

[Yellow Fang]

Surely, if you need the seatpost to be shorter, don’t pull it out to its full extension.
There is a small plastic insert available to set the height at a specific height too.
Or, have I misunderstood your issue?

That's what I do at present, but it takes me a while to work out how far I need to extend it. On my old L3, I just pulled the post out as far as it would go.

 

[a.twiddler]

Assuming the standard seat post on your older Brompton was a good fit for you, the main advantage of it is that it is what the original Brompton was designed to work with. The longer seat post was produced because the average height of buyers supposedly increased over the years. This had the drawback that the saddle wouldn't go down as far when folded, making the fold less compact. No one has ever accused me of being tall so as my used Brompton came with the longer one, I replaced it with a used standard seat post, and soon found a buyer for the original one.
No point riding about with the extra length of tube if all it does is make the fold less handy.

An advantage of the expanded bottom end of the seat post is that it's harder for someone to pinch your saddle and seat post, but it means that you have to take the saddle off to get it out if you want to change it.

 

[T4tomo]

@Yellow Fang do you still have two Bromptons.the A and the L3
AFAIK you can just take off the saddles and swap the posts over, or just move the plastic 'shortener' from one to the other.

Or buy another...
https://www.brompton.com/p/730/sadd...3A7uE1RZFfr7IUINixL1-cAG83I2j_nn&Colour=Black

As an aside, if you have the L3 why do you want to ride the A (maybe it's at a holiday home or similar he muses)

 

[annedonnelly]

That's what I do at present, but it takes me a while to work out how far I need to extend it. On my old L3, I just pulled the post out as far as it would go.

Get the plastic insert. I did and it was no bother to fit.

Unless, of course, the longer post is causing problems with the fold.

 

[Yellow Fang]

@Yellow Fang do you still have two Bromptons.the A and the L3
AFAIK you can just take off the saddles and swap the posts over, or just move the plastic 'shortener' from one to the other.

Or buy another...
https://www.brompton.com/p/730/sadd...3A7uE1RZFfr7IUINixL1-cAG83I2j_nn&Colour=Black

As an aside, if you have the L3 why do you want to ride the A (maybe it's at a holiday home or similar he muses)

The L3 was nicked. It was pretty old and worn. I was pretty glad to get the A-type, although I don't cycle very much any more.

 

[PeteXXX]

The seat post on my S6L is slightly too long inasmuch as when I drop the seat on folding the bike, the bottom of the post hits the ground so I have to be careful if I'm on concrete or hard ground. It could do with being ½" shorter.

 

[MontyVeda]

The seat post on my S6L is slightly too long inasmuch as when I drop the seat on folding the bike, the bottom of the post hits the ground so I have to be careful if I'm on concrete or hard ground. It could do with being ½" shorter.

I could be wrong but presumed the 'hitting the ground' is so the post acts as a brake for the rollers to stop the folded bike from rolling away.

 

[PeteXXX]

I could be wrong but presumed the 'hitting the ground' is so the post acts as a brake for the rollers to stop the folded bike from rolling away.

Possibly 🤷‍♂️
I prefer it to not be grazed, though, and not leave it anywhere steep enough to be an issue.

 

[wafter]

IIRC the bottom of the post is flared to impinge on the frame insert and prevent it escaping when deployed, so you'd not be doing yourself any favours by chopping it off.

As others have said, use of one of those placcy inserts to limit travel to the desired height seems the best way to go.

 

[a.twiddler]

As to the plastic insert, bear in mind that it's meant to be cut to size once you're happy with the setting of your saddle height. You might be able to cut a bit more off it, but you can't lengthen it again. Fortunately, for a Brompton item, it's relatively inexpensive.