NigelHealy

So I've been tweaking this over 8 years and this is the current version

• S- bar for lower body posture, a little faster
• Longer wheel base also for lower position and less knee-banging when riding out of the saddle
• SRAM 6speed rear (3spd hub, 2speed derailleur), efficient close gears
• Rack for spill-over capacity, particularly as the S-bars put a maximum front pannier limit.
• Schlumpf Mountain Drive 56T multiplies the 6rear to make 12 evenly-spaced close gears
• Steel frame for rigidity under load and strength
• Ergon grips for comfy on longer days

Cockpit with Ergon grips


Schlumpf Mountain Drive



heel-changing downshift 2.5x

https://s334.photobucket.com/albums/m421/NigelHealy/Brompton/?action=view&current=MVI_0529.mp4 12 evenly space gears 18"-97"



With exception of swapping a Brooks saddle to this bike (and a clean!) its now done.

The weight penalties add all up, it weighs 31.6Lbs / 14.3Kg as its shown.

rex615

Nice set up, I particularly like the grips.

Excuse my Brompton ignorance,

"* Longer wheel base also for lower position and less knee-banging when riding out of the saddle"

But is this a long wheelbase model or did you make some kind of modification to increase the the wheelbase?

NigelHealy

The Brompton extended its wheelbase by an inch in late 2003, a few months after I got my first Brompton.

The current frame+Sbar produces the same geometry as a roadbike when comparing the grip area of Sbar with the top position of a drophandlebar, the Ergon bar-ends produces very similar position to hands facing forwards on the brake hoods of a drophandlebar. What you're lacking is the few inch lower position for downhills.

fietsbob

Mk 4 main frame is longer than the Mk 2. the inch was probably added 1/2 on each side of the hinge.

the new H stem did 30 mm on each side , this year , for a 6cm added height..

One issue I see in Brompton's P bar is the lower drops position for going down hill
and into a headwind, is there, but if you have to hit the brakes ,
you have to move your hands. UP to get to them ..

NigelHealy

I'm not using P-bars for exactly that reason. S-bars is lower than M-bars but brakes right by hands. Even with hands on the bar-ends shown I can touch the levers a little.
I don't know why Brompton doesn't sell P-bar with a pair of brake levers connected, then I'd be interested, or someone make a kit, because even S-bars is higher than the dropped lower position on roadbikes.
I know some people who fit those arm-rests extensions.

fietsbob

B's M bars are fine by me, at my height. about goldilocks for an Old guy.
though I've seen pictures of substituting a Modolo Dumbo adjustable trekking bar
for M bars , on that stem, though some clamp bolt loosening
is definitely needed.. to fold down that bit of kit.

QBP has doubler parts to use 2 levers for one brake, so You could do that.
Brompton's designs seem pretty conservative, , think about it a long time
before making subtile changes ..

Hinge plates for example . from forged and hand fillet brazes
with a skilled person trained to do that job,

to A Cast hinge , added someone to machine each casting,
but the brazing is done with a torch array , and so more efficient
in parts produced per day.
a few jigs get the job done, and I presume de skill the jobs, a bit.

mike wingate

Do the Ergon bar ends compromise the folding aspect? Does it drag on the ground when folded. I do not have the rear rack, so you may gain a little clearance?

fietsbob

on the M bar, M3L, I keep a 5mm wrench stuffed in the frame, head end,
and loosen the 1 bolt on the GC3, rotate 1 up, the other down,
and it latches fine. end no closer to the ground, then

Shorter bar end may not need loosening.. it misses latching by an inch
with the long Ergon bar end of the GC3

NigelHealy

On M-bar, if the Ergon bar-ends when unfolded are horizontal, then they'll fit during fold but tilt the bike to the left as you fold then under.
On S-bar, loads-a-room.