Custom lots-of-titanium Brompton

I'm stunned this comes in at 11.1kg. My stock M3L is 12.2kg.

I think if I were you I'd be very tempted to swap for the 2-speed or maybe even go singlespeed, to really get the weight as low as poss. And put some lighter tyres on there. Just my 2p, it's lovely regardless and probably rides much better than stock.

Singlespeed and a little dosh of HTFU will sufficent.

Dan, take it to Richmond Park!

I am indeed very tempted to single speed it and fit Kojaks, albeit less tempted now I've got the 5 speed hub working reasonably well. However, I'm not going to, because I Have A Plan. And The Plan requires this Brompton to be my sensible all-weather commuting bike (I never said it was a particularly good or sensible plan). Once I've got this one just so, the Rat Brompton will be stripped and completely rebuilt in a way which does indeed make this bike look sensible and practical. But that's another story, and one which will told in mind-numbing detail much, much later. And will hopefully feature an attempt at an evens 10 mile TT on it.

In the meantime, I've finally managed to tweak the headset so it stays tight, continued (with some success) the fine adjustment of the 5 speed hub, and generally ridden the bike. Fettling to do features fitting the front luggage block, replacing the rear mudguard mount on the brake bridge (it's not stiff enough and bends when the bike's folded) and cutting down the handlebars by at least an inch each side.

BTW, my height stop on the seat post is lightweight insulating tape :o) I just read the instructions for that really expensive thing on the tat bazaar and improvised - works a treat.

Try this http://bromptontalk.wikispaces.com/Seatpost+Height+Keeper

There is a middle way on the tyres.

I run a Marathon on the back, where I get most punctures and it's a pain and a 15mm spanner to fix, and a Kojak on the front, which I rarely flat, has no chain to manage and can change with an Allen key.

I keep a spare tube in the frame, but with this arrangement haven't had to use it all winter. And while the bike feels sluggish with 2 Marathons, I can't really feel the difference between this arrangement and a pair of Kojaks, which averaged a puncture a fortnight over the summer.

What was the reason for 5spd hub instead of the Brompton 6 spd?

Am thinking of getting a Brompton and this thread is a huge inspiration.

We got some Brompton at work James, I'll give Madison a call tomorrow about the replacable soles.

We have a raw singlespeed one without mudguard and Kojak tyres.

^^ A variety of reasons really. A desire to something a bit different, doubts about the ergonomics of the Brompton's twin-shifter half-step gearing, a preference for the single thumb shifter on the 5 speed hub. And originally I was going for an 8 speed hub until I decided it was just too fat.

I now look back fondly at the 6 speed system though. The Ti Brompton may well end up being a 9 speed 3x3 Brompton at some point, as I'm still not that enamored with the 5 speed hub.

How have you found the mudguards in this weather?

Fine so far. Rode from KGX to work in the pissing rain this morning, and they definitely did the job. They're not as good as the standard Brompton mudguards - they don't go round the tyre as far - but it's pretty close.

^^ A variety of reasons really. A desire to something a bit different, doubts about the ergonomics of the Brompton's twin-shifter half-step gearing, a preference for the single thumb shifter on the 5 speed hub. And originally I was going for an 8 speed hub until I decided it was just too fat.

Another idea is using a Schlumpf 2 speed crankset.

It's also another way of adding 2 speed to your fixed wheel bicycle.

surly this is the only long term solution:

http://www.radsport-erdmann.de/images2/Alfine%20Di2%20set.jpg

^^ cheers. Not that I'm going to be able to do anything like this anytime soon, but I've been riding my dad's Brompton around recently and forgot what amazing little bikes they are.

Trouble with Alfine Di2 is that the OLN is 135mm, whereas a Brompton rear triangle takes a 110mm hub. So Di2 would require a custom rear triangle or some serious cold-setting of a steel one. Would be cool though.

say wha

Is this the one I saw in the flesh yesterday? Very tidy.

Yep, one and the same.

So who re spaced the frame?

Dunno but is much rather have a functional Kinetics mod such as rohloff/disc brakes than a rather pointless Di2 setup.

Or just stick to 3 speed, it's a folding bike, not a Robin Mather.

3 speed is fine.

Actually I'm glad I went for it. It's the right balance between weight and availability of gears.

Ryan has adapted a Brompton rear triangle for 135mm hub use- disc braked, from memory.

He did, it look impressive, wondered if he finished it yet.

Another idea is using a Schlumpf 2 speed crankset.

It's also another way of adding 2 speed to your fixed wheel bicycle.

this requires modding the BB though and not a particularly cost effective way of doing it (they cost a packet) - probably cheaper is buying an ebay hammerschmidt and buying the 130bdcd ring adapter, i'll be doing it if i decide to remove from the mtb

this requires modding the BB though and not a particularly cost effective way of doing it (they cost a packet) - probably cheaper is buying an ebay hammerschmidt and buying the 130bdcd ring adapter, i'll be doing it if i decide to remove from the mtb

Not necessarily there is a specific Brompton BB torsion arm, no need to modify the BB.

The Brompton's been working nicely and I've been using it every day. However, one of the rear spokes snapped recently, which is a bit of a PITA as removing the rear wheel of a Brompton is not entirely straightforward. So I took the rear wheel out, replaced the spoke, and refitted the inner tube and tyre. Sadly, I forgot to replace the rim tape, so that was one inner tube dead and another job to be redone.

While the rear wheel was out, I made a few improvements. The brake hanger bracket on the rear mudguard was a bit flimsy. The bike rests on the mudguard-mounted wheel when it's folded, and because the bracket's too fragile it folds up.

This means the pop rivets holding the bracket on rubbed on the tyre. The result was that every time you unfolded the bike you had to pull the mudguard back off the tyre, which was also a bit of a PITA. So I made up a new bracket from some beefier aluminium angle, and rather than two pop-rivets I've cut down two button-head titanium bolts and made up a titanium plate with two threaded holes in it.

The hole in the bracket is off centre as the holes in the mudguard aren't quite in line. The titanium plate with the threaded holes proved to be a bit of a challenge. I can't remember where I got the piece of titanium that's made from, but it's hard as nails. Making that cost 3 drill bits and an M5 tap.

Anyway, fitted it looks like this:

Seems to be doing the job so far.

I've also found a replacement for the standard Brompton chain-directing doo-dah on the chain tensioner. The standard one weighs 7 grams:

The replacement is a carbon one which saves a massive 2 grams:

So far it too seems to be doing its job. Which is nice. Oh, and I've readjusted the gear cable and things appear to be improving. I've now definitely got 5 different gears, and it seems to be a bit less clicky. Still needs some tweaking, but it's improving.