The Brompton Seat Post

[andyJH]

I am one of those guys that are right at the limit of the standard seat post. My inseam is just over 33 inches. When looking at a Brompton in the bike shop I noticed that the seat post extends to a hard stop. Is it safe to ride the bike at the fully extended position?

 

[Tenkaykev]

I am one of those guys that are right at the limit of the standard seat post. My inseam is just over 33 inches. When looking at a Brompton in the bike shop I noticed that the seat post extends to a hard stop. Is it safe to ride the bike at the fully extended position?

Yes, not a problem the seat post is flared at the bottom and can't go past the bottom of the downtube. If you want to remove the seat post you have to remove the saddle / pentaclip first and withdraw the seat post from the bottom of the downtube.
EDIT: Just to add that I'm in a similar situation and have been riding with the seat post fully extended for several years.

 

[CEBEP]

Same with me and I have Ti seatpost. Why it wouldn't be OK?

 

[u_i]

It is the size of the folded bike that dictates the length of the standard post, together with the ability to stop the folded bike from rolling, not the strength of the materials.

 

[sheddy]

a longer seat post is available

 

[cougie uk]

And an extendable seatpost is available after that.

 

[a.twiddler]

Here is the standard seatpost alongside the extended one for comparison

Here is the extended post with a measuring tape alongside.

There is an end plug at the bottom which you would have to remove from your existing one and fit to your longer one.
Hope that helps.

 

[a.twiddler]

On mine, the end plug looks like this. It's an allen head bolt with a wedge shaped nut which expands the rubber inside the end of the tube as it tightens. No danger of it falling out. In fact, I had to use a releasing spray to shift the bung once the bolt was loose. Later Bromptons might be different, this is a 2012 one.

The wedge shaped nut.

The bottom with the allen bolt head.

 

[shingwell]

A very old and old-fashioned country lass with a thick Gloucestershire accent (think Cider With Rosie), now sadly no longer with us, once said to me, "When we was nippers, we couldn' afford a saddle. We 'ad to tie an old towel to top o' tube and sit on that".

 

[andyJH]

On mine, the end plug looks like this. It's an allen head bolt with a wedge shaped nut which expands the rubber inside the end of the tube as it tightens. No danger of it falling out. In fact, I had to use a releasing spray to shift the bung once the bolt was loose. Later Bromptons might be different, this is a 2012 one.

The wedge shaped nut.
View attachment 633899 The bottom with the allen bolt head.
View attachment 633900

Thank you for the info!

 

[u_i]

On mine, the end plug looks like this. It's an allen head bolt with a wedge shaped nut which expands the rubber inside the end of the tube as it tightens. No danger of it falling out. In fact, I had to use a releasing spray to shift the bung once the bolt was loose. Later Bromptons might be different, this is a 2012 one.

The wedge shaped nut.
The bottom with the allen bolt head.

The new plug is just a piece of plastic, lighter and without an expanding bolt. It does not hold so well and it popped out for me after just a couple of years on the bike.