Category Archives: Tweaks

A contrast in blacks

With all the mods & tweaks to BB (my S6L-X super lightweight black Brompton), I realized that the only component original & unmodified was now the steel mainframe! Also, that meant my parts bin contained almost enough to build a complete Brompton – what I needed was an extra mainframe! Time to try a Ti mainframe? – & to resurrect Ralph for resale? (Ralph being my original S11E Alfine 11spd device that I’d decided really didn’t suit my current medical state & became the basis for the rebuild into the 8kg 6spd BB.)

So, an order was made for a Ti mainframe (from Ti39) & it was a simple & quick job to transfer everything onto the new frame. A glossy black 2mm tube affair, it seemed an impressive piece of art? Onto the scales & the complete Brompton weight is 7.4kg. As for a name, I thought it time to retire BB & go for BromTi (after all, some would say it’s not a “real Brompton” anymore?).

Once I’d stripped the steel mainframe for Ralph, the rebuild commenced; a slower affair, as every single component had to be installed (unlike the many whole assemblies transferred to the new frame). As I didn’t expect to be using Ralph, I decided to stick with an all-steel setup & with a Brooks saddle, Ergon grips, Marathon tyres & a new set of mudguards. All up, Ralph now weighs 13.1kg.

PS: An unexpected outcome has been the claiming of Ralph by Mrs Aussie – sheesh! another Brompton around the place!?



Some recent changes to my side of the Brompton fleet so here’s the status…

All are now running “minimal rain-guards” (yes, Sydney has been rather wet – for far too long).

Rudolph (10.6kg)

Chpt3 S9R-X with 38T chainring & 13/15/18T cogs (GIs 76-22)

After lowering Rudolph’s 6speed cog setup to the lowest feasible (15/18T, GIs 66-22), installing a 3speed shift conversion has given/restored some upper range flexibility (you never know when a tailwind will come along).

Clarence (9.15kg)

S4R-X with 46T chainring & 11/13/16/20T cogs (GIs 69-38)

BB (8.05kg)

S6L-X with 42T chainring & 11/13/16/19/22/25T cogs (GIs 62-27)

Even though BB’s 4speed setup was running well, I decided to make use of the 7speed freehub for some differentiation to Clarence. Tried a SunCord tensioner but disastrous, waste of time (wrecked the pusher due to excessive drag/friction in jockey wheel movement, maxxed the dogleg (start to contact with frame) as 5speed-capable only).

Obtained the new Thx4Ride derailleur & shifter & it’s running really well – although the Thx4Ride shifter steps didn’t mate with the 7speed cassette setup, so I’ve resorted to a 6speed cassette (I had to use mostly 9speed spacers, with thicker spacing for the first & last cogs – & a thin spacer to fill up the freehub).

The shifter benefits are that it’s very light (52g), mounts behind the bar (no fold clearance issues) & has a light action – all superior to the SunRace shifter in use with the 4speed setup. It would be nice if it is a trigger shifter but as a thumb shifter I’ve positioned it on the bar for thumb down-shifts & index finger (under the bar grip) up-shifts.

BB’s operation is delightful. Rudolph may have my lowest gearing option but the lightness of BB seems to put the two on a par?

Next tweaks? Maybe/probably finished?

Winged it

A 4-cog setup on BB has been an on/off, frustrating affair but now I may have resolved it!

An(other) inspection of the derailleur cable system confirmed that the cable had enough movement to suit 4 cogs but that the derailleur pusher wing-plate was restricting the rotation of the pusher, thereby causing inconsistency in shifting to the low cog (depending on cable tension, temperature, day of the week, etc?)

Some filing of the low cog wing-stop & all seems well?

Clarence & BB in their 9kg & 8kg 4speed guises


My conversions of some of my Bromptons into external gear 3speed & 4speed lightweight bikes is a personal thing, creating Bs that suit me & my limited power generation capabilities. I think that “power hides things” & I was bogged down by/with 3 factors; slow tyres, IGH hub drag, excess bike weight

Rudolph (Chpt3 v2 S6E-X) was “illuminating”, with fast tyres & a lot less weight than Clarence was running (S6R with Marathons, Brooks saddle, etc, etc). At first I couldn’t put my finger on what was holding back Clarence but once my experimenting with a 2speed rear wheel (acquired some time before, for “the parts bin”) & swapping accessories & tyres, here was a B that was lively & effortless (in comparison). With Covid lockdown (#1) & noticing lightweight parts available, the journey began!

Becoming aware/awake to component weight differences, I’ve tried to limit extras & only replace parts with lighter items. My extras are lights, bidon cage & essentially, a roller wheel extender to primarily protect the Ti rear frame “ears” (having seen a lot of pics of broken Ti frames with savaged roller wheel mounts, I’m hoping the extender is “insurance”?). Probably my first weight-saving consideration was the seatpost area. With a steel seatpost, Pentaclip & Brooks saddle weighing about 1kg, my replacements provide a saving of 500g – hence my following of the Brompton proverb, “Look after the grams & the kilos will look after themselves”. Nowadays there’s very little steel bits left on Clarence & BB, just the mainframe & stem?

Tinkering to improve/tweak performance has come from countless people before me, their tales littering the Internet. Lockdown learning skills & capabilities has shown that the tolerances to modify parts is tiny & often I’ve had to marvel at the original Brompton parts & design. I’d have to say that many of my Brompton tweaks require a “mechanical sympathy” & aren’t going to suit everyone – eg the SunRace shifter is great; I just need to feel when to feather the lever a touch! The whole derailleur system needs precise setup & variations between components & frame tolerances can make for some frustrating/baffling times – eg BB’s 3speed vs Clarence’s 4speed, where exactly the same derailleur & shifting components are used – but with different wheelsets!

So, to now see Brompton’s new P Line Urban models released is partly justification & reflective: I’m content with my creations but now I get to see how Brompton would do their redesign. In brief, I’m impressed/awed/appreciative – & already frustrated to see the “social media knockers”. I’m suspecting the first bike reviews to make many eat their words (hopefully not me?).

Perusing Brompton’s website (& apologies for pinching all the pics below) reveals countless touches – many unexpected. The P Line Urban seems truly a 2speed redesign, where the factory have noted flaws & taken their chances.

My main observations:

• The rear frame ears

• The external mudguard stays

• The 2-position seatpost locking

• The Pentaclip redesign (with oval saddle rail suitability)

• The derailleur design

• The rear hub design (& tweak possibilities?)

• The new 20spoke front wheel

• The roller wheel frame

• The website Support section videos

• The engineering efforts throughout

An earlier video? Due for replacement?

Now let me see, what weight savings could there be? Hmmm… golly, Clarence & BB are under threat!?

Lockdown learnings

Lots of Brompton fettling during our Sydney Covid lockdowns, mainly 3 older IGH bikes transitioned to Ti lightweights. Plenty of time to await parts, learn skills & tinker? New things for me were Ti fork & rear frame changes, lightweight headsets, Ti BBs & even wheel rebuildings. It’s all just Brompton Meccano really!

In preparation for finally being able to revisit our MidCoast beach unit (woopee, we got there last week!), I also resurrected some pre-Brompton steeds from storage, deciding that the coastal strip would be a good home for them.

The 20year old Giant MTB got by with a wash & lube & seems almost as new. I also had thoughts that the Trek TT bike would suit conversion to a single-speed beach cruiser, however plans got adjusted. The bike wash revealed an “exploded front hub” (something I discovered that era Bontrager aero wheel type was renowned for, but I could hardly claim warranty after 12years in storage!).

After retrieving another wheelset, I pushed on & stripped the TT bars & removed the large chainring. Instead of a single-speed setup, I used the rear wheel bar-end shifter & mounted it to the bullhorn bars (trying to make use of components wherever possible). With a single chainring & a 9speed rear hub, I cut back the cassette cogs to 7 to ease the chain line & dispense with the highest gears. Adjusting the derailleur limits for the 7cogs was perfect & it all seems to function well. (The setup has a 39T chainring & 13-23T gearing, pretty suited to my beach side cruising needs? – & now with a bike weight of 8.5kg)

Playing around with all this older technology made me aware of the likely difficulties of replacing parts in future, so decided to retain the Bontrager wheelset if possible. Finding a low spoke count front hub took time & when I dismantled the hub I discovered the rim used “hidden nipples” & that I couldn’t re-use the bladed spokes in the new hub! Very fast service from a WA spoke supplier & another wheel finished in quick time, if I may say so myself?

Only a couple of rides so far & I’ll need time to reacquaint with the twitchy TT handling – & I hope the locals aren’t upset about the rear hub buzz? (very loud; who needs a bell?)

BB genealogy

Aside from a new name, this little Brompton has undergone lots of changes during its life

• Built September 2011, probably as a S1E

• B11E UK modded with Bullhorn bars & Alfine 11speed IGH & sold to Aussie traveler

• S11E Sydney mods to replace Bullhorn bars, sold to me in December 2012 (name: Ralph)

• S11L mudguards added, various traveling (incl 2013 BWC & 2014 BAC)

• S11R-e GrinTech motor kit added, September 2016 (name: Ralph-e)

• S11E “naturally aspirated” during Sydney lockdown, June 2020

• S4E-X converted during Sydney lockdown #2, August 2021 (name: BB)

• S3E-X wheelset change, September 2021

Some drastic changes but maybe not as insane as they seem?

GrinTech mode was setup after giving up on waiting for Brompton’s e-version release. Very successful mod, although folded weight (23kg with battery) was sometimes awkward. Also, torque-sensing power delivery didn’t mate well with my health issues (“fatigue on big hills meant reduced pedaling effort, resulting in reduced power”; config best set to provide power at low human watts input; later GrinTech motors similar to Brompton version weight)

After my Chpt3 purchase (Rudolph) & finding that I could ride comfortably with an easy-rolling light bike, I removed the GrinTech kit during Covid-time & tried to get Ralph as light as possible & to compare with Rudolph & Clarence (now S4E-X modded). The project almost got to Rudolph’s weight but my conclusion was that the Alfine hub drag was too much for me. (The Alfine IGH was a good range of gears but suffers from increasing hub drag as you change to higher gears. Ralph may cope better with hills but elsewhere Clarence rolls so much more effortlessly.)

Lots of thought on whether I was likely to use (& enjoy) the new Ralph but it seemed inevitable that I ought to let Ralph go to a new home? Another lockdown & I decided to make Ralph enjoyable for me – by doing a Clarence act. So, now I have Clarence & BB (ie Black Brompton, Bitza Brompton, or whatever feels right as a name?) in similar but different configs. Clarence’s spec as a S4E-X now stands at 9kg, with mini rack & standard Brompton lightweight wheelset – sorry Brompton, your newly released P Line doesn’t interest me; too heavy, lower range of gears & “Clarence is already here” – in my favorite colour!

BB’s spec is a S3E-X & has various lighter components to weigh in at 8.3kg. Once again, lighter & a better range of gears (11/14/19T) than a new P Line version – although I’m sure Brompton’s new 4speed shifting is better integrated. (I’d like to say that I’ve given up trying to run BB as a 4speed; lots of tinkering but various factors involved (tensioner distortion, shift cable tension, derailleur clearances, wheelset hub dimensions, etc) but BB’s 3speed runs so well that I’m content – & resisting looking for any expensive bits/kits that may help?)

I suppose I’ll never decide which of my Bromptons is best. They all suit different situations & it’s always a difficult choice for a ride. Clarence & BB are so light & lively that porky Rudolph often gets overlooked?

Brompton Twins?

A lot has happened/changed in 2020 & our Brompton front is also rather different now.

Lots of tinkering has seen both Clarence & Peregrine swap from S6R models into lightweights with 3speed external gearing. Peregrine has lost about 3kg (now weighing 10kg) but Clarence has seen a bit more work in getting down to 8.7kg. Everything is running smoothly & delightfully after all the part sourcings & conversion work.

We also have 6speed lightweight twins (of sorts), after Rudolph has been joined by Ruby, a S6L-XD version that was obtained late-2019 in grey livery. Unfortunately the mainframe hinge had an issue & Brompton Australia (ta) obtained a replacement frame in House Red colour (grey no longer being available).

Having gained skills in rear frame & fork replacement, headset changes & external gearing tweaks, I’m figuring that wheel building skills ought to be next? How hard can it be? I’m nearly ready to go…

Headset ho

Some “elective surgery” today; a lightweight headset for Clarence.

Having earlier installed the Ti fork, the full headset swap seemed too tempting. I considered creating my own headset cup press tool but then I realized some cheapish tools were available so I took the safe path with my own purchase. The operation was precise & very smooth; all involved happy with the outcome.

New Clarence

No, not a new Brompton, just “a few little changes” to Clarence & now in S2RE-XX guise? (Yes, a strange model number – just my label for “rack with no mudguards & an extra-light Superlight”!)

My last posts of Clarence depicted an S6R Brompton & so the life-changes continue. When I think back on how Clarence has changed, I recall that the original build was a M6L but then converted to S6L before my purchase (thanks BA). Later a Brompton rack was added but now, after the latest component changes it’s really only the mainframe that remains from the major bits that came down the 2014 production line?

So why a 2-speed conversion? Since my Chpt3 Rudolph has proven to be so good for me, certainly in comparison with Clarence’s rather sluggish performance (with my health condition), I wondered what a lightened Clarence would offer. Easy enough to shed the rack & guards, I first swapped to a 2-speed wheel that I acquired during the Cheeky shop close. What a lively, easy-rolling feel that provided, & immediately with a bike weight equal to Rudolph. In concert with lower gearing changes for Rudolph, I also further lowered Clarence (from a 40T chainring to the smallest that would fit; a 38T ring). Sure it’s not some monster-geared speed machine; acquiring “MyVirus-08” has put paid to my being able to use that.

What I now have is a minimal-geared 2-speed Brompton, able to climb smaller hills & still provide an adequate speed on the flats & smoothly free-wheel down. The lack of weight & 2-speed hub combine for another benefit; the ability to easily roll Clarence when needing to walk up those hills too tough for riding. Totally enjoyable on all terrains, with 12-17T sprockets that provide a lower gear than Rudolph’s 3rd & a higher gear than Rudolph’s 4th.

The “extra-light Superlight” part of Clarence’s 2-speed conversion came about progressively during the considerable Covid-19 “StayHome” time of late. No long-term plan, just regularly finding bits that would suit Rudolph &/or Clarence. A greater appreciation of component weights & judicious shopping, often to address a particular issue, employing/learning mechanical skills & hey presto – Clarence has lost over 3kg! (An example of an issue could be the 2-speed swap highlighting the amount of drag in internally geared hubs. Aside from enabling the easy rolling, this showed the mismatched weights of the Brompton pedals & created the likelihood of “shin strike” when the cranks can rotate under gravity. My 150g lightweight pedals have replaced the 400g standard pedals, saving weight & my shins.)

Clarence vs Rudolph is now the experiment; what & where suits each bike will take time to decipher. A luxury of choice perhaps but such different characteristics that are both delightful to ride.

New Rudolph

Strange times, folks? Stay safe & keep up with your social distancing. Presently no lawn bowls & club activities, no travel, etc so plenty of reasons to blog post? Various things have happened with our Brompton family & I’ll start with my Chpt3.

I have been unable to pin down exactly what makes Rudolph so good for me to ride. From the first outing I’ve almost been able to keep up with Mrs Aussie, whereas a health condition usually sees me trailing far behind. Is it the fat & fast tyres? Is it the lighter weight than our other Bromptons?

Whatever the reason, I’ve also had the desire to avoid mods to Rudolph that moved away from the special Chpt3 look. Thinking now that Rudolph’s lightness should not be sacrificed, any changes would have to be for a very good reason. After all, most common mods (eg grips or saddle) also add weight & so I had to be careful & picky when thinking I could improve anything.

A great improvement for me has been the smaller chainring. The gear range is now far more useful, with a much-needed low 1st gear & the ready use of the highest gears (where previously I would rarely need 6th gear). Shifting through all gears during a ride provides an enjoyable flowing treat.

A rack makes a Brompton so practical for movement when folded (& stability when parked). I’m sure Andrew Ritchie never originally intended an E model Brompton & probably would agree that the folding frame geometry is flawed without mudguards or rack. (If the angle of the mainframe hinge was different, the folded E model would sit evenly on both wheels & so avoid its tilt toward the left – making it vulnerable to toppling over.) About a quarter of the weight of a standard Brompton rack (& that’s ignoring the weight of mudguards & stays), the lightweight rack suits an E model perfectly.

Another notable weight reduction is the lightweight pedals (fixed on the right, removable on the left), more than making up for the rack weight. I’ve been noting the weights of all my Brompton component changes & it’s surprising what a difference there can be. Overall, Rudolph is now lighter than original & ideally setup to assist with any weight reduction of my own?