Author Topic: Brompton builder  (Read 3760 times)

whosatthewheel

Brompton builder
« on: November 05, 2018, 11:21:06 am »
I'm lucky enough to be able to wait 12 weeks for one to be built... and I am about to place the order, just waiting for the C2W voucher to be issued

I'm thinking S2E  S type bars, 2 speed, no guards. I could also go 3 speed and guards, like my wife's, but having ridden hers, I find I never use the 3rd gear (and her 2 gear is bigger than the second gear on a 2 speed, 62 inch Vs 56 or so). Mudguards are nice, but me thinks the handful of times I really need them, I can just use her bike  ;D
Given the plan is to get a Brompton so I can carry it on the bus when the weather is foul, it seems a bit pointless to fit mudguards.

Colour wise, I'm thinking full white... I like white, it's classy and it goes well with any future upgrade I might want to do.

Kim

  • Timelord
Re: Brompton builder
« Reply #1 on: November 05, 2018, 11:56:29 am »
White bike with no mudguards.  That's courageous, as they say on Yes Minister.   :D
To ride the Windcheetah, first, you must embrace the cantilever...

Samuel D

Re: Brompton builder
« Reply #2 on: November 05, 2018, 12:08:39 pm »
Three-speeds, like other bicycles, are usually geared too high. I’d set up a 3-speed so that top gear is a comfortable cruising gear on the flat, but they’re usually set up so that 2nd is like that, 3rd is not nearly used enough, and 1st is too high for ideal climbing.

With a Brompton I’d be tempted to go single-speed for lighter weight, better reliability (I’ve heard bad things about some 2-speed hubs), and because I’d hardly ever care about climbing speed while riding it. If you go slow enough you can climb anything with a single-speed. It’s trying to climb quickly at the wrong cadence that is the problem.

I’m not giving you advice on this because I know you’re an experienced cyclist with a good technical understanding. Actually, I’d like to hear why you want a 2-speed.

Samuel D

Re: Brompton builder
« Reply #3 on: November 05, 2018, 12:12:23 pm »
As for colours, this is what Frank J Urry had to say in 1956 in Salute to Cycling:

“Some time ago I stood on the gallery of Earls Court and saw the colourful display of hundreds of bicycles, and on closer inspection came to the conclusion the trade had done a fine and very attractive job in the decoration of their wares. No wonder the young folk fall for the bright coatings and think little or nothing of the possible appearance of their property after a year of wear and tear – and weather. Colour and plating do not make a bicycle run easily or smoothly, it merely adds attraction to an attractive article and undoubtedly assists in the selling of it. Any maker or dealer will confirm that statement. But, and again I am giving my own opinion, the proof of any make of machine is in the riding, and the colour of its skin adds nothing to its running values. If the tinted bicycle with its attractive panels of paint and plate is to retain its smart appearance, it will involve you, or someone, in frequent cleaning and polishing. By this you will realise that while I admire some of the colour combinations, I prefer all black, preferably rubberised enamel, for the finish of my own machines.

“It lasts in respectability; a simple wipe over restores the major portion of its neatness after a period of winter neglect, and as most bicycles are more neglected than preserved, including mine, and if you prefer simplicity to fashion, then the all black finish is to be recommended.

“I don’t suppose that suggestion will be followed by the younger generation as proven by the insistent desires of my grandchildren.”

Kim

  • Timelord
Re: Brompton builder
« Reply #4 on: November 05, 2018, 12:14:23 pm »
Three-speeds, like other bicycles, are usually geared too high. I’d set up a 3-speed so that top gear is a comfortable cruising gear on the flat, but they’re usually set up so that 2nd is like that, 3rd is not nearly used enough, and 1st is too high for ideal climbing.

I think Bromptons in particular are deliberately geared for muggle cadences.  They do offer smaller chainring options.


Quote
With a Brompton I’d be tempted to go single-speed for lighter weight, better reliability (I’ve heard bad things about some 2-speed hubs), and because I’d hardly ever care about climbing speed while riding it. If you go slow enough you can climb anything with a single-speed. It’s trying to climb quickly at the wrong cadence that is the problem.

I’m not giving you advice on this because I know you’re an experienced cyclist with a good technical understanding. Actually, I’d like to hear why you want a 2-speed.

Hang on, isn't the Brompton 2-speed the same single speed hub with an extra sprocket?  The main argument for two speed is that since you need all the chain tensioner gubbins anyway to facilitate the fold, the weight penalty of the wiggly version, extra cable, sprocket and shifter is negligible.

The disadvantage is that the derailleur is quite good at gunking up, compared to a purely hub-based transmission.  Equally applicable to the 6-speed, and presumably a non-problem if you're the sort of person who cleans their bike.
To ride the Windcheetah, first, you must embrace the cantilever...

Samuel D

Re: Brompton builder
« Reply #5 on: November 05, 2018, 12:32:12 pm »
Hang on, isn't the Brompton 2-speed the same single speed hub with an extra sprocket?

Don’t know. I suppose you do. I tried to find the “S2E” on the Brompton site but only found a tedious bike-builder so gave up. I guessed it had a 2-speed IGH with kick-back shifting, like my mother’s Sachs-hubbed Monark a long time ago. That was a good arrangement because it eliminated the shift cable and its associated problems, but the modern Sturmey-Archer Duomatic doesn’t seem to have a good reputation for reliability.

The main argument for two speed is that since you need all the chain tensioner gubbins anyway to facilitate the fold, the weight penalty of the wiggly version, extra cable, sprocket and shifter is negligible.

I see. Still wonder if it’s worth the minor weight penalty and increased maintenance. On the other hand, adding another gear to a single-speed is worth more than adding a third gear, which is worth more than adding an 11th gear, etc. What’s the opposite of diminishing returns?

whosatthewheel

Re: Brompton builder
« Reply #6 on: November 05, 2018, 12:34:12 pm »
Maintenance is not an issue. I keep my bikes in good nick

The third gear is something I might need once a year if I take the bicycle to Yorkshire for holiday with my wife... but I am unlikely to miss it for the remaining 364 days. It implies the Sturmy Archer, which is heavy and I will have to carry it two flights of stairs all the time. On balance, easier to push the bike up that steep 15% bend once a year. Besides, my wife will push hers even with the 3rd gear, so I might as well join in.  :thumbsup:

Single speed is too restrictive... it means in essence anything beyond my normal commute becomes problematic. I reckon I can do a long 6% climb on the 56 inch gear, probably not on the 74 inch one.

I see two speed as the best compromise between single and 6 speed.

Gear ratios are

2 speed standard    56.0” 4.47m    74.7” 5.96m
3 speed standard    47.9” 3.82m    63.8” 5.09m    84.9” 6.78m    
3 speed -12%            42.1” 3.36m    56.2” 4.48m    74.7” 5.96m


Re: Brompton builder
« Reply #7 on: November 05, 2018, 12:47:03 pm »
Maintenance is not an issue. I keep my bikes in good nick

It's a nylon bushing pointing downwards at best 6 inches from the road. It takes very little to gunk it up enough that the return spring can no longer move it far enough to shift, leaving you stuck in low gear.

Of course an occasional single speed is still more useful than a full-time single speed.

Kim

  • Timelord
Re: Brompton builder
« Reply #8 on: November 05, 2018, 01:01:05 pm »
Hang on, isn't the Brompton 2-speed the same single speed hub with an extra sprocket?

Don’t know. I suppose you do. I tried to find the “S2E” on the Brompton site but only found a tedious bike-builder so gave up. I guessed it had a 2-speed IGH with kick-back shifting, like my mother’s Sachs-hubbed Monark a long time ago. That was a good arrangement because it eliminated the shift cable and its associated problems, but the modern Sturmey-Archer Duomatic doesn’t seem to have a good reputation for reliability.

I've seen Kinetics doing custom builds with such a hub:

http://www.kinetics-online.co.uk/folding-bikes/brompton/cableless-brompton/
To ride the Windcheetah, first, you must embrace the cantilever...

Re: Brompton builder
« Reply #9 on: November 05, 2018, 03:43:20 pm »
If you buy an S2L, converting it to an S2E only requires two parts (cable disc fender to keep the front brake cable off the tyre, and a standalone hook for the LH front axle nut).
Never tell me the odds.

whosatthewheel

Re: Brompton builder
« Reply #10 on: November 05, 2018, 06:23:44 pm »
If you buy an S2L, converting it to an S2E only requires two parts (cable disc fender to keep the front brake cable off the tyre, and a standalone hook for the LH front axle nut).

good point

citoyen

  • Cat 6 Racer
Re: Brompton builder
« Reply #11 on: November 05, 2018, 06:59:32 pm »
Single speed is too restrictive...

I commuted for years on a singlespeed on a route with a Proper Hill and it was fine but YMMV. I’m not convinced that 2spd is a massive advantage over singlespeed if you’re worried about hills though.

S2L would be my preferred configuration if I were buying a Brompton now. The mudguards are worth having IMO.

Standard gearing is plenty low enough for most uses. The reduced gearing is only required if you have very hilly routes and/or regularly carry lots of luggage.

Re: Brompton builder
« Reply #12 on: November 05, 2018, 07:07:36 pm »
Single speed is too restrictive...

I commuted for years on a singlespeed on a route with a Proper Hill and it was fine but YMMV. I’m not convinced that 2spd is a massive advantage over singlespeed if you’re worried about hills though.

S2L would be my preferred configuration if I were buying a Brompton now. The mudguards are worth having IMO.

Standard gearing is plenty low enough for most uses. The reduced gearing is only required if you have very hilly routes and/or regularly carry lots of luggage.
I cannot argue with any of that.
But my Brompton's most regular usage is getting the Sainos shopping trip up the incline to my house.
Hence the 50T chainring.
It works.

citoyen

  • Cat 6 Racer
Re: Brompton builder
« Reply #13 on: November 05, 2018, 07:39:21 pm »
There’s the thing - you have to choose your configuration to suit your dominant usage mode.

Let the occasional uses be where you compromise.

Re: Brompton builder
« Reply #14 on: November 05, 2018, 09:49:04 pm »
Mine has AM hub internals so it has three usable gears - 52", 60" and 69".  It climbs well as it's 21lb with bar ends and an almost locked-out rear suspension, so it can be hustled up steep hills ok.
Never tell me the odds.

quixoticgeek

  • Mostly Harmless
Re: Brompton builder
« Reply #15 on: November 05, 2018, 11:34:29 pm »
There are primarily two problems with the Brompton, both problems are lumps of squishy stuff. One is the lump of squishy rubber that forms the suspension block, and other is the squishy bit between pedals and handlebars.

The former, even with the most firm of the offerings from Brompton is not firm enough, unless you are either a) bloody light, b) not carrying much. Stick 100kg of dyke on a brompton, add 10kg of luggage, and even with 16 gears, it wallows about like a pig... You could argue that this use case is actually more a flaw in the 100kg of dyke, rather than the 50g of rubber... but it's something many don't realise. My Brompton has a 1.85m lowest gear, and a 8.18m upper gear. I have had cause to use all of these (65kph down hill on IoM was fun, 5kph up hill, less so...) My preferred gear for pootling around town is the 4.83 (38t front, 20t rear, 5th gear of the 8 on the SA hub), I have no idea what that converts to in archaic measures.

As for the mud guards yes or no. YES! Then you can fit an easy wheel to it, so you can wheel the bloody thing down the train platform, or round the supermarket. Better yet, stick a rack on so it's more stable to push round the shop. Rack + easy wheels is the best upgrade you can make on a Brompton for usability as a town bike.

J
--
Beer, bikes, and backpacking
http://b.42q.eu/

Kim

  • Timelord
Re: Brompton builder
« Reply #16 on: November 05, 2018, 11:45:26 pm »
It's like citoyen said:  If you want a bike that can fold, add all the toys to make it decently usable.  But if you want something that you can pick up and carry, the minimalist weight-weenie approach (and occasional use of either the 24" gear or Rule 5) makes more sense.

(The rack's something of a special case, as although it adds a fair amount of weight, it makes the folded bike a *lot* more manageable if you aren't just going to pick it up and carry it.)
To ride the Windcheetah, first, you must embrace the cantilever...

whosatthewheel

Re: Brompton builder
« Reply #17 on: November 06, 2018, 06:37:26 am »
There’s the thing - you have to choose your configuration to suit your dominant usage mode.

Let the occasional uses be where you compromise.

Indeed... hence 2 gears. I might compromise on mudguards... they might end up being more useful than not and as per above... a couple of cheap upgrades can rid of them altogether if necessary

Samuel D

Re: Brompton builder
« Reply #18 on: November 06, 2018, 08:28:46 am »
Standard gearing is plenty low enough for most uses. The reduced gearing is only required if you have very hilly routes and/or regularly carry lots of luggage.

But an 85" cruising gear (according to whosatthewheel’s gear table above) is pretty high for a slow bicycle. Does anyone find that more useful than a lower gear for climbing steep hills? I wouldn’t.

The 56" and 75" gears on the 2-speed sound reasonable although I’d probably still prefer a slightly lower cruising gear on a Brompton. When I rode one of these things the rolling resistance felt extreme.

Re: Brompton builder
« Reply #19 on: November 06, 2018, 08:30:11 am »
IIRC it's quite a bit cheaper to get the mudguards and/or rack as part of the initial build than as aftermarket parts. My use case would be as an all-weather utility bike; obviously the silly-light (<8 kg) modded Bromptons are going to be easier to carry, but once you've committed to guards and a rack I'm not convinced the difference between say 11 and 13 kg makes all that much difference, especially as you only have to carry it up stairs or when folded.

whosatthewheel

Re: Brompton builder
« Reply #20 on: November 06, 2018, 09:03:36 am »
Standard gearing is plenty low enough for most uses. The reduced gearing is only required if you have very hilly routes and/or regularly carry lots of luggage.

But an 85" cruising gear (according to whosatthewheel’s gear table above) is pretty high for a slow bicycle. Does anyone find that more useful than a lower gear for climbing steep hills? I wouldn’t.

The 56" and 75" gears on the 2-speed sound reasonable although I’d probably still prefer a slightly lower cruising gear on a Brompton. When I rode one of these things the rolling resistance felt extreme.

I wouldn't want to go any lower than 75" as biggest gear... agree on 85", I also find it a bit big, although I managed to keep it for almost all of the commute on my wife's bike, as a bit of a challenge  ;D

https://www.strava.com/activities/1938901881

Re: Brompton builder
« Reply #21 on: November 06, 2018, 09:09:01 am »
The 56" and 75" gears on the 2-speed sound reasonable although I’d probably still prefer a slightly lower cruising gear on a Brompton. When I rode one of these things the rolling resistance felt extreme.

An unencumbered Brompton is not a slow bike. The Marathons they usually come with aren’t the smoothest, but if you keep them near max pressure (which a lot of people don’t) they roll well enough.

(The highest gear on mine is 106 inches and it gets regular use)

whosatthewheel

Re: Brompton builder
« Reply #22 on: November 06, 2018, 09:16:28 am »

An unencumbered Brompton is not a slow bike.

Agree... I worked out it's about 1 mph slower than my carbon road bike on a rolling terrain, even less difference on a completely flat terrain

Re: Brompton builder
« Reply #23 on: November 06, 2018, 09:28:12 am »
A jubilee clip (or two) around the firm suspension block makes it usefully firmer.
Never tell me the odds.

whosatthewheel

Re: Brompton builder
« Reply #24 on: November 06, 2018, 09:33:15 am »
A jubilee clip (or two) around the firm suspension block makes it usefully firmer.

I find the firm suspension firm enough... I have noticed they no longer offer the soft one