alex1234

Hi all,

In a previous post I was asking how to build an ultra-light folder bike. I pulled the trigger and bought a Brompton P Line (10kg) using a cycle2work scheme, so I was wondering:

1. What is the lowest weight possible I could achieve by moding this bike?

2. Which parts would you change? I am trying to make a list of weight reduction mods for the P Line

Note: I would like to keep its main frame (which is steel) for now (might buy a titanium one in the far future) - also I would like to keep the mudguards as London is quite rainy

Thanks!

Jipe

First thing, if you make a lot of changes to a P-line to reduce its weight, you will end up with a total price exceeding the one of the T-line -> better to buy immediately a T-line.

Limited changes to reduce the weight are the saddle (for something like an AX-lightness Leaf) and the brake levers + brake calipers for instance for Ridea levers and calipers or better (but much more expensive and more difficult to do) for eeBrake calipers.

alex1234

Thanks! Good points. Thing is, with the t line, you can't really really find it anywhere , and secondly. I might be doing these changes slowly over time to distribute the cost, and also modding the bike can be fun for me. But yeah I agree with your point.

Jipe

You mentioned riding in London, I thought the T-line was now available in UK ?

Also, the Chinese Ti mainframe aren't comparable with the new T-line Ti frame and the T-line has a carbon fork, so whatever you do, an upgraded P-line will never be at the level of a T-line.

alex1234

Yes, they are available in theory. But no one has stock, you have to join the official Brompton store's waitlist and if you are lucky get an invitation to buy, but that is a big IF.
Also, the official Brompton store does not support the cycle 2 work scheme of my employer so I wouldn't buy it anyway.

Fentuz

You can fit:
- lighter tyres like schwalbe one which may save you 100g per tyre
- lighter inner tube like tubolito (~35g vs std ~80/90g) but when you get a puncture, they are a nightmare to fix (long curing time so you better carry spare tube--> against the objective)
- remove the 4 wheel rack, keep the single wheel mud guards (or remove them if it's dry)
- cables, look how much cable you actually need; cable length are usually too long and could be made shorter but, you need to check that the reduced length doesn't interfere with the mechanism and that the cable does not pinch. Replace the OEM cable with something like Jagwire elite sealed or elite link. Between the shorter length and the lighter material, there is a bit of weight saving.
- you could fit a lighter seatpost (like litepro) but watch of the weight limit, I would not got there if the load in greater than 80/90kg.
- you could fit a carbon handle bar and light grips
- swap the roller wheel for lighter ones
- fit lighter pedal (lightest pedal may not fold)

then, the more complex:
- remove the crankset and bottom bracket, bit a ultegra BB and carbon crankset for a single chainring or a GXP BB with a Force 1 or Red carbon crankset and a narrow wide chainring (I got a 50T with my force 1 by default) but this is expensive (£300)

then, there is a myriad of Titanium bits and carbon bits with various quality (see potential failure, bad mechanism etc.) that will reduce the weight but they are expensive and can spoil the ride.


But As somebody else said it s expensive and you may end up with something that is more expensive that the OEM upgraded version. Also, look at the cycle2work scheme condition; in my case, I was suppose to keep in original (other than maintenance condition) until a paid it fully. All the upgrade were quickly reversible, spare wheel, seat post were fine but I swapped the groupset / crankset when the repayments were completed.

Also, you may want to review the chapter3 spec and use it as inspiration.

alex1234

Wow, that's an amazing and comprehensive list of upgrades, thanks a lot for that!
yeah I agree, it could be expensive but unfortunately i can't find the t line anywhere.
also, another thing that didn't mention is that the reason I am trying to reduce the weight so much is to offset the weight I will add by converting it into an ebike using the swytch kit (conversion weighs about 2.6kg) and the swytch kit doesn't work with the t line's new fork

50PlusCycling

For an all-around townie (if your town is reasonably flat) a Brompton is a great bike. I’ve owned two of them (both were stolen), and enjoyed them both. I like how they fold, and how they ride, I am not bothered much by their weight. The only downside is the limited gearing which forces me to get off and push them to the top of steeper hills. In Asia I have seen Brompton copies made by “Mint” or something like that. They look like Bromptons, but with conventional off-the-shelf Shimano drivelines and disk brakes. I’m not sure about the build quality, but they don’t look badly made.

I’ve been on the fence about getting a featherweight folding bike to keep at our place at the beach, and have had my eye on a Panasonic Traincle. These are compact, 14” folding bikes made of titanium, and come in two versions. The one I’ve been looking at is the better model with the tubular titanium fork (instead of the pressed steel fork), and has been fitted with a Dura Ace 9 speed cassette and derailleur. With a light saddle and pedals it’s about 7kg. I’m not keen on the 14” wheels and tires, but the price is less than a 3 speed Brompton.

Fentuz

I thought the swytch was about 1.5kg and the newer battery is supposed to be more compact and lighter. Either way, if you go for that, check the crankset/BB compatibility before you swap for a lighter hollow tech system.
Also, the added torque and stress from the swytch kit is likely to be OK with standard QC/QA brompton parts, it might not be the case with lighter 3rd party components that may not have the same QC/QA policy as Brompton of any other know manufacturers.

alex1234

That is correct, it's 1.5kg and the new battery comes in 1.1kg and 0.7kg flavors depending on the mileage you want. The motor comes pre attached to a front wheel (included in the kit).
I'll probably get a torque arm for it to avoid damaging brompton's titanium fork

alex1234

Sorry to hear you got two bromptons stolen!
may I ask how did it happen? Did you lock them outside ?
also, the Traincle looks very interesting! It's funny how many cool bikes there are out there that we don't know off