Brompton owners

@Tenderloin knows

It is if you look at the ones available from St John Street Cycles.
I have a Brompification one - I don't remember it costing as much as the TiPW ones.
Nor was it as cheap as the one you've indicated.

Too good to be true? Can’t say but the seller gets a pretty bad rep for massive delays and cancelling orders. I can vouch for that.

I actually find it’s better to order through Aliexpress than ebay when buying from China. All the poor experiences I’ve had have come from ordering on eBay over Ali. Those seatposts are regularly available on Aliexpress. I’ve ordered a custom length (650mm)Ti post with a flared end for c. £80

I think there might be some Ti which is higher grade and also the machining on the bromptonification stuff is top end (can’t say about SJS stuff). I still don’t have one of them in my hands but hopefully will by end of the month so will report back then

That's good to know, will be interested to hear your feeback on the seatpost (when it arrives).

Yes and no.
While the seat post is a thing of beauty (£154.00 a couple of years ago btw),
I also had some Brompification QR pedals which, having done fewer than 200 dry miles, developed slop in the RH pedal bearing which (when they saw my video of it) SJS deemed to be unacceptable. I returned the pedals and received a full refund, which SJS would've taken a hit on as, by that time, Brompification had ceased trading.
Props to SJS.

Ah haven't seen the pedals - that sounds pretty annoying

Ask them for the weight

Website says 280g for a 600mm, lighter than a Brompification 520mm. They must be using that new titanium

A lot of the cheap ti posts are cheap for a reason, that’s all I’ll say.

70's ford cortina?

It is a very long seat post, how thin can the material be?

I don't get the weight thing, tho.

Titanium is generally only made in two commercially-available grades, 6al/4va and 3/2.5 (aluminium and vanadium being the alloying elements).6/4 is tubing, 3/2.5 is for plates and solid pieces. Neither is exactly cheap so generally cost savings are in production. It’s a bugger to work with (it’s extremely abrasive and eats cutting tools, for example) so components tend to be pricey, but assuming the manufacturers can get the tubing rolled out to the right diameter there isn’t much to do to make it into a Brompton seatbpost.

Incidentally, most early ti bicycles used commercially-available aviation hydraulic and fuel line tubing, which was only produced in a limited range of diameters, as it was far too expensive to get custom-drawn tubing, and so early ti frames were very skinny.

All this titanium talk is giving @Multi_Grooves a stiffication

6/4 is tubing, 3/2.5 is for plates and solid pieces.

Other way round I believe. 6/4 isn't normally available as tube, so you end up having to form 6/4 tube by bending plate into a tube and welding the seam, rather like ERW steel.

'Ti-6Al-4V has always been the first titanium choice in the aerospace industry. Due to the fact that it is not a malleable alloy, it is more commonly used in sheet and plate applications.'

This^. I believe.
My first Ti frame was 6Al/4V.
Only one of a handful sold in the UK.
When it developed a crack around the BB, it was replaced under warranty, but with a 3Al/2.5V frame, on the basis that Reynolds deemed 6Al/4V tubing too expensive to produce commercially, and would only do so as a special order.

ETA - It was a f'ing stiff frame, which still had springiness.

And I've just ordered a 6Al/4V frame...

I'm curious.
From whom?

Lynskey. An R470 disc frameset.

Delightful.
Enjoy.
ETA - I have no doubt that you will.

I had one of the previous incarnation of those. It was very heavy and slightly over maximum luggage size. But it did always get through.

When airline security fucked it up by prying the (unlocked) locks open, I replaced with with the soft-sided bag. That's been working just fine ever since. When folded, the Brompton is a surprisingly tough little package.

6Al/4V alloy can be superplastically formed/diffusion bonded, but that's probably a bit expensive for tube (or even frame!) forming...

Correct! My mistake. I’m a certified aircraft engineer, saw more titanium than you’d believe but it still used to make me go “oooh, lovely” each time.

Looks like Sugino have changed things up since I bought my cranks in 2007, so I owe you an apology... Have they changed the taper since 2007? Sugino used to advise the use of an ISO BB, we went over it all on this very forum countless times... Also NJS = ISO... Those fancy cartridge Sugino BBs weren't available BITD, my S75 BB was a loose bearing thing that I was afraid to take out in the rain... 111mm ISO Campag Chorus was the favoured upgrade...

Just joined your silly clown bike club, and if you see me around town on a very shiny silvery s6l, say hello.

Hello Jurek.

BTW, do I really need to service the main hinge on the rear triangle thing twice a year ?