I used to have a Dahon Jetstream EX on my boat. 20" wheels, full suspension, very light, great to ride. Nearly perfect boat bike except just one thing -- doesn't fold up very small, and fold is awkward. Storage space is a terrible problem even on big boats (mine is 54 feet) so I eventually took it off.

I have loved my Riese & Müller Multicharger on land, which has made car ownership or even carsharing nearly irrelevant living in various European cities. Obviously this is far too large and heavy for a boat. Electric drive is a revelation.

I have been thinking about Bromptons which have the most ingenious fold, sacrificing riding quality with no suspension, few gears, and small wheels, but storage is the key quality for this use case.

I had not considered any kind of electric bike because of all the weight it adds. Then a lightbulb went off in my head -- Brompton Electric has its battery in a bag which you just pull off. With the battery off, it's only a kilo or so heavier than the normal Bromptons. If I can lug it on and off the boat, sometimes using the dinghy, in separate packages, the weight is much less of a problem. Bingo.

So now this is my Plan A. Which model to choose? There are:

1. C-Line Electric, can be had with the H6 gearing, all steel and £1000 cheaper than the P-Line.
2. P-Line Electric which has titanium frame elements and some better components. £1000 more expensive.

Neither has disk brakes, which I've come to really love on the R&M.

So maybe buy a used C-Line, and kill two birds with one stone -- buy the titanium rear triangle and forks with disk brake lugs you can get on Ali Express, and convert to disk brakes?

Anyone have any views/thoughts/experience on this?

The 3x2 = 6 speed Brompton are obsolete, replaced by the better 3x4 = 12 speed system on both the C-line and P-line.

For a boat that I suppose goes on the sea = salt water, the titanium parts are better since the steel rear triangle is sensitive to rust.

Thanks for that!

I'm looking at used ones on FleaBay which still have the 6 speed. 12 speeds better of course. That one has a Shimano hub gear instead of Sturmy-Archer? That would of course be a big upgrade. Must research,

OK, so i see I made some wrong assumptions.

The new 12 speed uses the same Sturmey Archer 3-speed hub as previously. The difference is the derailleur.

Disk brakes won't work with the electric hub drive, and in general apparently they interfere with folding.

So all that seems out.

There's an H6L electric on FleaBay which might fit the bill. The P-Line looks nice but the better components are all lighter, particularly wheels and tyres, which is maybe not good for my application, which will involve hauling fairly heavy loads of groceries to the boat.

No, the 12s has a Surmey-Archer 3s hub almost identical as the one of the 6s, the only difference is that it accepts 4 cogs instead of 2.

Combined with this hub, there is a new "advanced" derailleur with 4s instead of 2s which is more reliable/less sensitive to dirt than the 2 s derailleur.

So the advantage of the 12s vs. the 6s is a bigger gear inch range, smaller gaps between the gears and a more reliable derailleur.

For new bikes, the price difference between the 6s and 12s is very small with as consequence that a used 6s should become cheaper than it was before the 12s.

Hey, OP, you know what you want, you've measured the space you have and listed your mandatory requirements. Far be it from me to waste your time by suggesting a Plan B. For anyone else in a not-too-dissimilar situation:

https://usa.dahon.com/collections/bi...hon-k-feather?

(In that great Dahon tradition, the specifications listed are absurd and contradictory. Sigh.)

6spd C Line is 31lbs 12oz w/out battery,P Line 4spd is 28lbs 3oz. The battery in the small bag adds about 7.5lbs.

I won't touch anything on Ali. The quality varies wildly and I know folks who have gotten ripped off. Also,you won't be able to run the Sturmey hub with discs.

Mechanic at the DC Junction here. Most of the folks who have gotten Brommies for boat bikes have either just gone with an A Line to save dosh,or they've gone with a P or T for the weight savings.

That looks great!!

I will look into this.

How big is your sailboat that you need a Folder to get around on it let alone a geared or electric one......I'll see myself out.

I am not sure I would purchase a bike, sight unseen, especially a Brompton. You can't test the hinges to see if they are worn, you don't know how much juice the battery can hold and what consumables need replacing. Purchasing in person would be the better option.

Rust is an issue but with care that can be mitigated. I would go for the C Line as it is less expensive. Sure the P Line has some titanium parts but you still have to care for everything else. The C Line has two more parts to care for. Heck, even a T line would need care. The only beneficial thing the P Line will be the lighter weight to help when you carry the bike on and off your boat.

Common in these boards is "more gears are better" mentality. I do not follow this mantra. Three speeds are more than enough and if you have electric assist, does it really matter? Walking up a hill isn't a crime in the cycling world.

My neighbour has an electric Brompton and she swears by this bike, she just loves it. I haven't seen what version she has but she rarely touches her non-electrified Brompton anymore.

Good luck with your purchase, your plan sound excellent and well thought out.

The gear ratio of the 3-speed hub is wider on the 12 speed set up. Otherwise, the post has it correct.

I think I'd probably go with a regular P-line. Save the battery & charging hassle.
Did you know salt water is a LOT more conductive than fresh? So that getting the battery wet could ruin it. You don't need that worry.
Yes, the new 12 speeds still have the 3 speed IGH. The big advantage is the 4 speed cassette, vs. 2. It lets you leave it in the much more efficient direct gear in the IGH for more of the time.
You'd go to the 1st gear in the IGH for climbing, where you won't likely notice the lost efficiency, since it's geared way down.
Only in the top gear of the IGH would you notice it, really.
The money you save by NOT getting the electric, you would spend on the saved couple of pounds and corrossion resistance of titanium vs. steel in those parts. Of course you will try to keep it dry, but things happen.

As far as I know, its not: the BWR of the 12s has the same gear inch range as the BWR of the 6s (and has of course a wider gear inch range than the BSR of the 3s like on the A-line)..

The total wider gear inch range comes from the wider gear inch range of the 4 cogs.

The BWR's are all identical except for the cassette body(2 8spd cogs or 4 10spd cogs) and the rim/spokes. Internally there's no difference.

I stand corrected. I looked into it and you are right.

We have two 6-speed analog C-lines that spend most of the summer in the aft cabin of our Pearson 38. We store them in Brompton Transport bags, which roll up and store in a small handlebar bag. When folded,they both fit in our 10.5 foot Achilles dinghy.

Brompton’s engineering is ingenious. We bought them as “land tenders” for the sailboat, but are using them more and more for trips and everyday riding. In May, we packed them in B&W Foldon cases, airlined to Heathrow, took the train to Lancaster, and rode the Way of the Roses cycleway across England on our Bromptons. These are real bicycles.