Sampson titanium bottom bracket and Sugino LP cranks with aluminum chainring, the combo weigh significantly less than OEM steel B/B and steel chainring/chainguard.

I used a Bontrager alloy stem/super light Race handlebar, cut off 1 1/2" from both ends to narrow the bike for my commute. Plenty of other stem/handlebar combo that can be lighter.

I replaced the OEM freewheel with a Sachs Regina alloy freewheel, that is also significantly lighter.
OEM brakes were replaced with 1st gen Shimano LX V-brake, lightest and likely the most noisy brakes under the right conditions.
OEM brake levers were replaced with Avid Dial7, OEM rear derailleur replaced with XT; all parts I have laying around in my basement.. all lighter than OEM.

Wheels/tires I leave OEM until they wear out.

I can probably fit a $60 16" Chinese carbon fork and change the OEM headset for lighter unit also.

Brompton pentaclip would be nice, but I rather have a one-piece seatpost.

For now, I'll keep everything as is until stuff breaks during my commute.

Actually a pentaclip is the same as what you have only aluminum.

Yes, and I want a seatpost with clamp that's one piece.. not seat clamp that separates from the post.

Another reason not to use 28T rear sprocket freewheel: Ground clearance.

Below image is a 23T rear sprocket with added chain links (added weight).
Lower pulley of the rear derailleur is about 1" off the ground.

Using a larger rear sprocket would require longer chain (add more weight) to avoid the lower pulley dragging on the ground while riding.. or just go with a shorter cage rear derailleur to maximize ground clearance.

http://i238.photobucket.com/albums/f...r/IMG_7704.jpg

BTW, swapped out the B/B and cranks to Rival alloy/Red carbon crankarms and EXO B/B for additional weight saving.
http://i238.photobucket.com/albums/f...r/IMG_7705.jpg

http://i238.photobucket.com/albums/f...r/IMG_7703.jpg

http://i238.photobucket.com/albums/f...r/IMG_7702.jpg

I have a Dahon Speed p8 that is at 29lbs without the water bottle yet, but has a saddle bag with a multi tool and 3 lights, an upgraded octalink ultegra crankset, schwalbe marathon kevlar guard tires, rear rack and skx fenders. I think the fenders,racks,tires and the seatpost pump with the wtb saddle are major factors why my bike is heavier. Also I swapped out the telescopic handlepost for a 27cm fixed fnhon outside fold handlepost ( lower position). I think I can get the bike at leasts 5lbs lighter by switching out the weight factors, but them it would be a less of a commuter lol
Nice looking bike btw, thinking of getting a tokyo for international travel

Thanks.. My little Citizen Tokyo is a pure commuter, have other bikes to ride for travels or performance oriented rides.
I keep the bike minimal without bags or water bottle cage because I have to walk along the bike to get it through NYC subway and PATH train turnstile entrance:
http://spoilednyc.com/wp-content/upl...ba8_o-4821.jpg
http://www.subwaynut.com/path/23/23_5.jpg
Luckily, I still have a slim figure with all the pedaling that I do, I can fit through with the bike.

Even though my Speed is my commuter, it still gets most of the mileage, though for weekend riding I'll hop on my trek 7.2fx for added comfort. I'm on the heavier side at 210lbs and with the double crank set-up, I can tackle New York tolerably. Sometimes people that I rode with, either on road bikes or fixies, are surprised that such a small machine can keep up with theirs (Just don't go past 25mph on the flats because I'll be struggling by then) haha

25 mph in NYC is just accident waiting to happen... not only if impact occurs, but if you run over a nice pothole, cobblestone or sheet metal cover w/sharp edge.. flat tire, taco wheel.. ride to survive.

True that, I really avoid any metal while riding since tires don't have any traction on them especially when they're wet. If I do go beyond 20mph, it's really me putting a lot of effort, I just cruise within 10-18mph. I agree with ride to survive, I would always slow down or stop whenever I'm in a turning street or someone from incoming traffic is gonna make a turn since I've had experiences when drivers either don't see me or just think they have the right of way always. Ride safe always!

I know it's been awhile, but was just wondering if you still like your Gotham 24-7, and if it's able to go up smaller hills (paved trail) without having to walk it up? I've got a 3 speed hybrid bike now, and always have to walk it up anything that looks like a hill. Am interested in this one so I can keep it in the car and hit the paved trails in the area, all are a little hilly.

I'm on my 3rd Citizen bike now,
https://i.imgur.com/SWoBmpo.jpg
Previous two bikes were both stolen.
One while stored in lock basement, the other stolen from a school yard and I could not chase down the thief on foot.
Sometimes I hate NYC.

Lots of good info on folders in here, especially Citizen. I take it you guys like them? :)