Brompton owners

Genuine question? Why rear rack? I struggle to see what use it have after having a front block.

Girlfriend wanted one so she could wheel it around sainsbury's easier

Genuine question? Why rear rack? I struggle to see what use it have after having a front block.

Because better wheeling of the bike like @RankinJ said, mostly (I felt the need for this many times), and ability to carry more stuff...
I'll report on whether this was a good move or not but I genuinely wanted to try since I had a Brompton (nearly ten years)

I use mine for non-Brompton luggage.

You're right, it is easier to wheels it than the 3 wheelers set up on the standard Brompton, it make sense in supermarket that doesn't have a trolley.

My 2 speed Brompton has developed a high pitched chitter, up there with chalk on blackboard - but definitely chittery, whenever/ not always (but I can induce it 90% of the time) I go over rough tarmac, speed bumps, potholes, drain covers etc.
It is coming from the front end of the bike, and as I say it it chittery, rather than cyclical.
It has that dry metal on dry metal flavour to it.
I thought it might be from the points of contact between the main hinge clips and the frame (I have the Brompification variety) so I've given the mating surfaces of both some lithium grease - with little or no effect - which makes me think a) Try Copaslip and b) it is something else.
Anyone else experienced anything similar?
It isn't a high mileage bike and has hardly ever been out in the rain.

Could be something rubbing on the mudguard, can't tell you much without assessing the bicycle.

Not sure it is the mdgrd, Ed. I've had mdgrd noises before, following a clumsy fold, and this isn't synonymous with one of those.
I'll put money that it is metal on metal - very high pitched and quite jarring. I wouldn't mind if it was a nice noise - but it is not.
I am hoping someone might say 'I know what that is - I had it on my Brompton' to save me going through the process of systematically covering all mating surfaces on the front end of the bike with grease and then test riding it....

First thing first, are you aboustely certain it's coming from the front?

Best thing you can do, put the bike on the stand, check every nut and bolt is torqued, checked clearance, pads, cable etc. and spin the wheel while on the stand to hear it.

Could be hub bearing need repacking.

I'm certs it is the front end of the bike, @edscoble.

Probably yes. I run a tight ship. Albeit I push it to the fail envelope.
Which ones are you thinking of?

I had a noise. I'd got the ti hinge bolts. They came with little Allen bolts to stop the bolts from undoing too far. I didn't fit them with loctite and they unscrewed themselves and rattles around in my frame. Especially noticeable over bumps.

Probably not that, but can't think of anything else.

In other Brompton news I've finally fitted my 58t ring, new sprocket and chain (104 links as per Scoble's instructions). Also, cleaned the mech, took ages. Very dirty.

Haven't had time or inclination to test ride it, so hopefully it'll be OK on tomorrow's commute...

Haven't had time or inclination to test ride it, so hopefully it'll be OK on tomorrow's commute...

Go out and test it now.

Brompton survived the commute.

New big gear was fine even into this morning's headwind, and the slightly higher lower gear was a bit more useful than usual. I'm looking forward to this evening's tailwind commute home :)

Also, cleaning the mech and sticking a new chain and sprockets on have made everything run nice and quietly. I need to clean everything more often...

Especially the rear 2 speed derailleur that get fogged up quite easily.

My advice? Buy another one, so you can fit the new one on, and soak the old one properly to removed all the gurk (small flat headed screwdriver work best I have found).

Not a bad idea at all, think I'll get one for next time.

I found hot water, fairy liquid and a 2mm allen key did the trick, really fiddly to get in all the nooks and crannies though.

You'll find a small flat headed screwdrivers easier as you can push the gurk out from the side instead of fishing it out from the inside (if that make sense).

I'll put money that it is metal on metal - very high pitched and quite jarring.

I may have had something similar, on my Brompton, with both the original 1992 main frame and the replacement frame I've had since 2012.
On both frames a little bit of grease on front hinge mating surfaces helped (btw it's not the hinge that failed on the first frame). I never tried grease on the actual V-shaped aluminum hinge restraining part as I've always assumed an aluminum/steel contact wouldn't make that specific noise (one being softer than the other), but I'll try...
Nothing here you haven't already tried so far but recently as the noise came back a little I noticed that tightening the wing nut too much (I tend to tight the hinges like a brute) was actually promoting the "dry metal" noise, and to my surprise tightening less (more like a normal person would I suppose) made the noise disappear.
It was never very pronounced anyhow, just a little dry "click" noise as I pedal harder, seems that in your case it's worth, so I can't tell if it's the same phenomena. (I'm using the original Brompton parts btw)

Thanks for this @veLLo.
I will look into it, as I come from the bastid-tight school of wingnuts.

What are my options for a stiffer spring?

Firm block with jubilee clip(s) around it is the quickest / cheapest option.

Not titanium though is it

Viagra

http://extreme-bolt.com/products-titanium-hose-clamps.html
https://www.amazon.co.uk/RockBros-Titanium-Spring-Suspension-Brompton/dp/B011U0GGDI

that's a very personal question.

75kg