Author Topic: Brompton seatpost height insert (Read 8618 times)

Kim · « **on:** 31 January, 2015, 07:10:02 pm »

They've finally come up with a solution for reproducing the correct seatpost height. Looks like a bit of cable trunking, cut to fit and inserted into the seat tube to stop the post at the appropriate height:

http://brilliantbikes.co.uk/brompton-handlebars-and-seat-posts/1804-brompton-saddle-height-insert.html

https://www.youtube.com/watch?v=pShWaKl0RHQ
http://youtu.be/pShWaKl0RHQ

I still think that some measurement markings on the seatpost would be simpler, though this approach is quicker if the bike's only being used by a single rider.

Canardly · « **Reply #1 on:** 31 January, 2015, 07:21:52 pm »

Worrafaff.

Kim · « **Reply #2 on:** 31 January, 2015, 07:29:03 pm »

I seem to have managed - entirely through luck - to have achieved the right combination of short cranks, saddle and fore-aft saddle position, that the seatpost height is pretty much spot-on when fully extended. At least when using the SPDs - I have to drop it a bit for the flat pedals.

Otherwise I'd order one. It's not an elegant solution, but one-off faff beats faff every time you unfold it. It's fiddly enough making the saddle straight.

Asterix, the former Gaul. · « **Reply #3 on:** 31 January, 2015, 08:56:03 pm »

Quote

New for 2015 the Brompton Saddle Height Insert allows you to pre-set the height your seatpost will rise to when unfolding the bike.

Isn't that the thingy that stops you pulling it right out?

Kim · « **Reply #4 on:** 31 January, 2015, 09:34:31 pm »

Quote from: asterix on 31 January, 2015, 08:56:03 pm

Quote
New for 2015 the Brompton Saddle Height Insert allows you to pre-set the height your seatpost will rise to when unfolding the bike.

Isn't that the thingy that stops you pulling it right out?

Different thingy. It works in combination with that to stop the post short of its full length. The video makes it clear.

hellymedic · « **Reply #5 on:** 31 January, 2015, 09:51:58 pm »

All the way out on a standard seatpost is *just* right for self and partner so nothing else is needed.

Jurek · « **Reply #6 on:** 31 January, 2015, 09:54:53 pm »

CD marker / Sharpie FTW.
That is all.

Tewdric · « **Reply #7 on:** 31 January, 2015, 10:34:01 pm »

All the way out on an extended seat post is what I do, with the pentaclip reversed and every last mm taken mounting it on the seat post. I could probably do with another cm or so but its of no consequence compared to not having too faff about with a telescopic post. Bro miss are all about quick, easy and convenient.

LittleWheelsandBig · « **Reply #8 on:** 31 January, 2015, 10:59:09 pm »

I use a telescopic seatpost even though I could probably get away with an extended seatpost with everything else maxed out. The top telescopic section is rarely moved, so the saddle is at the perfect height when the main section is extended.

Biggsy · « **Reply #9 on:** 01 February, 2015, 12:55:21 pm »

Marker pen ink soon rubs off my Brompton post. The thingy might be easier than lining up with a mark anyway. Thanks for posting, Kim.

drossall · « **Reply #10 on:** 01 February, 2015, 08:27:14 pm »

I must be thick. I've watched the video and I still don't see how it works - possibly because I have a Dahon rather than a Brompton. Interesting though, it's a pain getting the saddle at exactly the correct height.

Kim · « **Reply #11 on:** 01 February, 2015, 08:37:44 pm »

Quote from: drossall on 01 February, 2015, 08:27:14 pm

I must be thick. I've watched the video and I still don't see how it works - possibly because I have a Dahon rather than a Brompton.

Like a wizard's staff, a Brompton's seatpost has a knob^[1] on the end. This gets stuck against the bottom of the constriction in the seat tube caused by the clamp mechanism and is what stops you pulling the post all the way out. The tactical cable trunking effectively extends the clamp constriction downwards through the wider^[2] seat tube, causing the post to stop at a lower height.

_{[1] Which also acts as a brake to stop the folded bike rolling away on its easy wheels.
[2] Wide enough for the knob to pass.}

drossall · « **Reply #12 on:** 01 February, 2015, 08:43:43 pm »

It's easy when you know

Thanks. I should have remembered that. I have ridden the odd Brompton borrowed from friends.

Paul · « **Reply #13 on:** 02 February, 2015, 09:05:09 am »

Quote from: Kim on 01 February, 2015, 08:37:44 pm

Like a wizard's staff, a Brompton's seatpost has a knob^[1] on the end.

This is a gratuitous post merely to signal appreciation for the lovely simile.

resus1uk · « **Reply #14 on:** 02 February, 2015, 11:47:24 am »

Just fitted the insert to my M3 with the standard seat post.
Easy to do. Video on Youtube helpful & I found a printout of the instructions in english on an italian Brompton site.
Take care opening the cardboard packing as the instructions are printed on the inside.
I got mine post free from Brilliant Bikes as my local agent hadn't heard of the insert.

Ian

jsabine · « **Reply #15 on:** 02 February, 2015, 11:56:15 am »

Quote from: LittleWheelsandBig on 31 January, 2015, 10:59:09 pm

I use a telescopic seatpost even though I could probably get away with an extended seatpost with everything else maxed out. The top telescopic section is rarely moved, so the saddle is at the perfect height when the main section is extended.

<s/rarely/never>

^This.

Kim · « **Reply #16 on:** 02 February, 2015, 01:37:17 pm »

Quote from: jsabine on 02 February, 2015, 11:56:15 am

Quote from: LittleWheelsandBig on 31 January, 2015, 10:59:09 pm
I use a telescopic seatpost even though I could probably get away with an extended seatpost with everything else maxed out. The top telescopic section is rarely moved, so the saddle is at the perfect height when the main section is extended.

<s/rarely/never>

^This.

Alternative strategy for tall people who value a smaller folded package:

Telescopic seatpost with the telescopic section fully extended. Use the insert to set the extension of the main post to the desired height. Seatpost can then be fully collapsed and reproducibly extended to the right height.

jsabine · « **Reply #17 on:** 02 February, 2015, 01:47:14 pm »

That would work, but I've only got a couple of inches extension on the telescopic post so it doesn't really increase the volume significantly.

GothonaBrompton · « **Reply #18 on:** 02 February, 2015, 03:48:52 pm »

Works well for me. I actually have an aftermarket seat post with markings on, but you try seeing them when it is dark when you leave the house and your outside light is a bit cr*p, or same on station platforms of an evening at the moment. Hubby has his own Brompton plus he doesn't like mine anymore since I changed to a ladies Brooks saddle. So I don't need to set it high enough for him.

I am 5ft tall so for me it was money well spent - just pull the seat up to full extension and make sure its pointed in the correct direction.

LittleWheelsandBig · « **Reply #19 on:** 02 February, 2015, 03:55:54 pm »

The small brass Kamoya height stop (bonded in place) was a vertical prong that fits up the slot in the plastic bush and ensures the saddle is correctly orientated.

Hello, I am Bruce · « **Reply #20 on:** 06 March, 2016, 02:48:46 pm »

I have a 2nd hand Brompton. How do I tell if there is an insert (and remove it)?

I see a plastic bushing inside the seat clamp (Is this just a bushing that is always there?). I don't see the locator tab that is part of insert, but perhaps they break off. From leg measurement, I am boundary of normal vs. extended seatpost. Height is ok at the moment, but I'd take an extra cm of height if I could get it. I suspect there is no insert, but would get rid of it if there is.

Kim · « **Reply #21 on:** 06 March, 2016, 03:05:23 pm »

FWIW You can easily gain a centimetre by raising the saddle clap up the post a little, if you haven't already. Or by getting lucky with an alternative saddle. Not sure about the insert; I've cunningly got the right length legs for the standard post at full extension, so don't have one.

rogerzilla · « **Reply #22 on:** 06 March, 2016, 08:02:55 pm »

I needed one, or a very small part of it, for the M-type with a steel extended post. I didn't need one for the S-type with a Brompton titanium post (no longer offered). It seems the titanium extended post is a little shorter than the steel one.

LittleWheelsandBig · « **Reply #23 on:** 06 March, 2016, 08:38:32 pm »

Quote from: Hello, I am Bruce on 06 March, 2016, 02:48:46 pm

I see a plastic bushing inside the seat clamp (Is this just a bushing that is always there?).

That is the normal bush that eliminates any need to grease the seatpost. The height adjustment insert fits between the flare at the bottom of the seatpost and the bottom of the sleeve. If it is there (probably not), you'll see it when you completely lower the seatpost.

The Brompton seat clamp can be fitted with the saddle rails either above or below the clamp bolt. Not many saddles have enough height for the rails to be mounted in the lower position but the current Brompton saddle does and factory Bromptons come that way. Changing to the upper position might give you a little extra height.