Brompton

Discussion in 'General Cycling' started by Jim, Sep 14, 2011.

  1. Jim

    Jim Guest

    x-no-archive:

    I'm thinking of investing in a Brompton, initially for several weeks
    touring which will also involve much bus travel:

    1. What is the tallest / longest inside leg limit for them?

    2. What is the weight limit over which one wouldn't feel comfortable
    riding them?

    3. A six speed can be purchased with a 33" inch lowest gear. I would
    want something nearer 20". What is the easiest way to replace those
    huge dinner plate chainrings with one of about 32t?

    4. Do they come with a front rack, or do you need to buy one of their
    overpriced bags to get a rack?


    5. Is there anything else I should know?

    TIA
     
    Jim, Sep 14, 2011
    #1
    1. Advertisements

  2. Jim

    mrc7--urcm Guest

    In message <>
    If you're looking for a folding bike with a wider range of gears there
    are alternatives to the Brompton such as Dahon, Airnimal and Birdy.

    Mike
     
    mrc7--urcm, Sep 15, 2011
    #2
    1. Advertisements

  3. I'm 6'2", and found that one with the standard seatpost fully extended
    was practically unrideable, but the optional extended seatpost was fine.
    (Both on a short trial ride, I don't own one.)

    http://www.evanscycles.com/products/brompton/aluminium-extended-seatpost-ec024140
    claims "riders with an inside leg measurement of up to 35 inches".

    Depends on your riding style, I think. I'm around 100kg and think it
    would be fine, but I wouldn't want to get out of the saddle and haul
    on the bars.

    (Weight limit for touring in bags is another matter, and isn't perched
    on a long seatpost and stem away from the frame in the same way the
    rider's weight is.
    Here's a photo of one with a fair amount of touring kit on:
    https://secure.flickr.com/photos/armb/2871832149/ )

    Pass. I've seen discussion of changing gearing, including chainsets,
    but I don't know if there are any special considerations where going
    beyond some size limit will interfere with folding.

    You can buy just the carrier frame separately, but I suspect that's not
    what you want. I think they just come with the mounting block as standard.
    http://www.evanscycles.com/products/brompton/front-carrier-frame-alone-ec007508
     
    Alan Braggins, Sep 15, 2011
    #3
  4. Jim

    Peter Clinch Guest

    Whatever it is, it's with the telescopic seat post (a standard
    option). Tony Raven is, IIRC, 6'5" and uses one okay so it's a
    fair size. I use the standard seat post right at the top, my
    inside leg is ~ 30" but I do like my seats higher than most people
    (Roos has the same seat a couple of inches lower if she borrows it,
    and her inside leg is ~ 34")
    Depends how it's distributed, and for what values of
    "uncomfortable". I find that if I really pack out the front
    pannier with heavy stuff (i.e., glass bottles of liquid) then the
    handling suffers. Not that I'm "uncomfortable" in a worry about a
    crash sort of way, but it would be substantially less like fun
    covering any distance.
    So for touring get the rear rack. It's very low as rear racks go,
    of course, so panniers aren't going to work: stuff will need to be
    on top.

    But see http://stein.dommel.be/brompton/chapters/Luggage.html for
    some interesting possibilities.
    As you would on any other bike. Though note that your top gear
    will then suffer a lot too.

    Other options would be a Schlumpf Mountain Drive (works well on
    Broms, according to a pal who has one), or a fancier conversion
    like the Sturmey 8 speed Ben Cooper of Kinetics does.
    They don't have a front rack. As for the bags being over-priced...
    in strict material terms you have a point but in terms of how very,
    very well they work you get very good value for money IME/HO. The
    bag incorporates its own rack so the fold is not affected and the
    mount is on to the main frame tube rather than the fork so the
    steering is less directly affected (though see para 2 above).
    Guy might have an opinion, /if/ he has such a thing as a Brompton...

    Pete.
     
    Peter Clinch, Sep 15, 2011
    #4
  5. Jim

    pete Guest

    One of the standard configs from Brompton is the 44t chainring which I
    use for hilly trips, giving a 29" bottom gear which does me for most
    things. I'm sure people have set smaller - check the bromptontalk list,
    below.
    Yes, the latter, in effect. You need to buy the front luggage block then
    I think you can buy the bag frame seperately. I'd be surprised if there
    were no 3rd party front racks though I've never gone looking.
    Get Ergon grips. The standard bar grips can be a bit of a pain after ~10
    miles.

    For a range of answers, both knowledgable and opinionated, to these
    questions and more join the Bromptontalk mailing list:

     
    pete, Sep 15, 2011
    #5
  6. With the telescopic seat post, easily 36". My 34" is fine, Tony Raven
    has a brom and is taller than me.
    They are pretty tough. The pannier block has a weight limit I believe
    but I know a gentleman of relaxed proportions who regularly rides a
    brom while festooned with brass instruments and other loads. He did
    once break a rear triangle, but I think the design has improved since.
    No idea, you might want to contact Steve Parry if he's still in the
    The pannier block is necessary for front luggage. The bags are made by
    reputable firms such as Radical and Carradice, they are not cheap but
    they are very durable and well made. I think they are not overpriced.
    Yes, I would recommend flat bars over butterfly or moustache as they
    are stiffer. Also you can replace the pedals with SPDs without
    seriously compromising the fold. The Brompton rear rack is OK but you
    need to watch the width of any load as it can catch your heels. And
    the Schmidt dynamo is superb.

    Guy
     
    Just zis Guy, you know?, Sep 15, 2011
    #6
  7. I'm 6' and a bit.

    I ride a Bromton with the optional extended seatpost fully extended.
    It is just the right height for me.
    Similar. The bars seem very flimsy for bigger people.
    Don't bother with 6 speed. All it is is the 3 speed with half gears.

    I cannot help with lowering the gearing.
     
    Bertie Wooster, Sep 15, 2011
    #7
  8. Jim

    Peter Clinch Guest

    On 15/09/2011 19:30, Bertie Wooster wrote:

    [Brommies]
    I personally don't like the 6 as it's extra complication I don't
    particularly get on with... but then I mostly use my Brommie as an
    urban hack-bike rather than a tourer. You do get a bigger range
    and closer spacing, both of which have attractions for touring.

    Though Mike's suggestion of one of various non-Brommies or the
    custom route (Steve Parry's derailleurs or Ben Coopers Sturmey 8 or
    either do a Rohloff(!)) would do a better job if it's serious
    gearing options you're after.

    You can tour on a Brom, and part of the attraction is doing it on
    something that is assumed not to be able to, but there are better
    suited folders or disassemblables if the prime goal is going on
    tour in places it's a beast to get a "normal" bike to.

    Pete.
     
    Peter Clinch, Sep 15, 2011
    #8
  9. Jim

    Biggles Guest

    I have telescopic seat post, 35" inside leg, have at least 1" more
    extension to go so at least 36" inside leg should be possible.
    IIRC Brompton advise a weight limit of 110Kg all up. I'm around 100Kg
    and feel the need to treat the bike with more respect than my other
    bikes (mainly hybrids). My Brompton certainly felt flimsy the first few
    times I rode it, mainly I think due to handlebar flex (I have a P type,
    or "butterfly" handlebars), but I soon got used to it. You must accept
    that it's a design compromise - there's a trade-off between folding that
    small, light weight and stiffness. I've ridden mine with a fair bit in
    the (huge) front touring pannier and it handles well. I wouldn't want to
    tour on it seriously though unless I was travelling VERY light.
    Don't know if it's possible to get down to 20", but -12% gearing is an
    option which gives 29" on the 6 speed. I see comments in this thread
    about the 6 speed being of not much use. That is not my experience. The
    3 speed hub on the 6 speed has VERY wide spaced ratios (much wider than
    the 3-speed) and the 2-speed rear sprocket provides nicely spaced
    intermediate ratios. To use these effectively you do need to change both
    levers at the same time, which takes a bit of getting used to.
    The bags are superb, in no way would I call them overpriced - they
    certainly are expensive.
    If you have big feet (which may go with a long inside leg!) I would
    advise against the standard "Rack Sack" rear bag - my feet tend to foul
    mine. With conventional panniers on other bikes I mount them rearwards
    to avoid fouling but this is not really an option with the Brompton.

    Biggles
     
    Biggles, Sep 16, 2011
    #9
  10. Jim

    mrc7--urcm Guest

    In message <>
    The advantage of the standard Brompton is that it folds down very
    quickly and neatly into a relatively small volume that can make it ideal
    for commuting where the cycling at each end is straightforward. On the
    other hand once you start considering use for touring you then introduce
    questions about the volume of luggage and how easily it can be carried
    on the bike, as well as questions about whether that then compromises
    the ease of folding and also the volume of the folded bike.

    The OP also makes mention of regular uses of buses and a problem there
    is that restrictions on luggage may come into play. For example in
    Cambridge the newly opened Guided Buses have a rule that folded bikes
    should be in bags and put in the luggage area, and that no more than two
    bikes are allowed per bus.

    On the other hand for touring, particularly with luggage you might be
    interested in a bike that has greater range of gears, better road
    handling and also luggage carrying capacity. I have an Airnimal Joey
    Commute with an 8 speed Alfine giving a gear range of about 36-96
    inches, but the Joey Explore offers 23-113 gear inches.

    http://www.airnimal.eu/Joey/Explore.php

    The Joey can be folded quite quickly and there is a lightweight bag into
    which it can then be put for transport. There are also numerous luggage
    carrier options that people have used when touring with a Joey (and
    other Airnimals).

    see http://www.airnimal.eu/Reference/Gallery.php

    Mike
     
    mrc7--urcm, Sep 16, 2011
    #10
  11. Jim

    Jim Guest

    x-no-archive:

    OP here.

    Thank you for the comments and the links, and I note the corrections
    of my ignorant comment on the price of the baggage. My impression is
    that the Brompton would be best used as a simple bike, for relatively
    short journeys, as a single speed. TheAirnimal Joey looks practical
    as a long distance tourer. I will need to make a decision based on
    what I think my longer term use will be, as well as the immediate
    trip. Actually, I probably <need> both of them.
     
    Jim, Sep 22, 2011
    #11
  12. Jim

    Peter Clinch Guest

    For values of "short" I'd put at < 10 miles, though other riders with
    better or worse legs will have different numbers. Whether or not single
    speed is appropriate depends very much where they are. Hacking up steep
    bits of Glasgow on my way to CyclingScotland HQ last week I was rather
    glad of my lowered-ratio 3 speed.
    Of /course/ you do!

    Pete (with a Brom and a disassembling Moulton).
     
    Peter Clinch, Sep 22, 2011
    #12
  13. Jim

    Ian Jackson Guest

    Coincidentally, I've pretty much decided I need a folder too. I've
    just had the straw that broke the camel's back - one more journey
    which was more complicated and faffsome than it ought to have been.

    I don't plan to be touring on it and my main use will be rail+bike
    journeys (often in London). I guess any one bike stage is going to be
    under half an hour and probably less. Looking at the alternatives it
    does seem like the Brompton is by far the best option for intermodal
    journeys.

    So I'm left with a bunch of spec choices. The two choices that are
    most unobvious are handlebars and gears. For the handlebars: my
    current main bike is a Thorn Audax mk3 with drop bars; I ride
    overwhelmingly on the tops, which are perhaps an inch lower than the
    saddle. (I use the drops in fierce headwinds.) Would I find the M
    too upright ? I have borrowed my partner's fairly upright Dutch city
    bike and the riding position doesn't seem too bad for shortish trips.

    For the gears I'm tempted to go for the 6-speed. With my Thorn I'm a
    bit pernickety about which gear I'm in at any moment. How much slower
    am I likely to be on the Brompton than the Thorn (in both cases with
    luggage, mudguards, etc., of course) ? My usual urban cruise (between
    junctions etc.) on the Thorn is 30+kph and with a tailwind I'm often
    still pedalling at 35+kph. The 178% gear ratio of the Brompton
    3-speed seems quite small. [1]

    As for luggage the only reasonable option seems to be one of the big
    front panniers, probably "T" as I have been known to travel with two
    20-25l rear rack panniers. I assume that carrying my Altura Urban
    Dryline 17 laptop pannier on a Brompton's rear rack is a non-starter.
    It would probably ground going round RH corners, at the very least.

    Why do Brompton link LED front light with the SON dynamo ? Do you
    think they would do me the Shimano dynamo with the B&M LED headlight ?
    I don't want to go back to halogens!


    And one final point. I'm an occasional international rail traveller
    and I can imagine myself taking a suitable bike to use abroad - but on
    long distance journeys I carry a lot of luggage. Typically I have a
    large rucksack. I can carry this rucksack on my back while riding my
    Thorn. Of course the less-upright riding position helps here as it
    means the rucksack doesn't pull me backwards; the weight is carried
    well on my back, bum and arms.

    Is that a mad thing to imagine doing on a Brompton ? Carrying the
    bike folded through the international rail network, for use at the
    destination, would be another option but I don't relish running
    through the Paris Metro (say) with a bike alongside all the rest of my
    luggage!


    [1] I should really quote the gear ratios of my Thorn but I'm not sure
    exactly what they are. Also the Brompton web page says "Ratios
    (metric)" and then quotes figures in meters. Of course a ratio ought
    to be dimensionless. Are the figures in meters ("gear inches") or are
    they ratios of revolutions ?
     
    Ian Jackson, Sep 22, 2011
    #13
  14. Jim

    Ian Jackson Guest

    Hrm, just reading about those 8-speed Bromptons. Sounds like a thing
    I might want. How heavy is it compared to (say) a 6-speed ? Can I
    get a new Brompton with it already fitted, somehow ?

    I found these pages:
    http://www.kinetics.org.uk/html/8-speed.shtml
    http://tillercycles.co.uk/page5.html
     
    Ian Jackson, Sep 22, 2011
    #14
  15. Jim

    David Guest

    Pete (with a Brom and a disassembling Moulton).

    What's up with the Moulton? You've not had it long.

    D
     
    David, Sep 22, 2011
    #15
  16. Development, perhaps?
    Differs from gear inches by a factor of pi (plus the inch to metre conversion)
    http://en.wikipedia.org/wiki/Gear_inches#Calculating_metres_of_development
     
    Alan Braggins, Sep 22, 2011
    #16
  17. Jim

    mrc7--urcm Guest

    In message <dkt*>

    [snip]
    I have a friend who has the P-type butterfly handlebars, but he say's
    that for regular use he'd prefer the weight saving of the S-type.
    But again what you get is intermediate gearing but at the expense of
    having greater weight when you carry it.
    I think you'll find that you'll be a lot slower, not only because of the
    gearing but also because of the more upright position causing
    aerodymanic drag.

    [snip]
    They look like metres of development, i.e. the distance you would travel
    in metres for a single revolution of the crank.

    My Airnimal Joey Commute with 8-speed Alfine has a gear range of 36-96
    gear inches which translates to approximately 2.9 - 7.7 m of
    development, slightly smaller than that quoted for the Brompton 6 speed
    2.6 - 7.9, but you could optionally raise that by 8%.

    7.9 metres of development would require a cadence of about 74
    revolutions per minute to achieve 35kph

    Mike
     
    mrc7--urcm, Sep 22, 2011
    #17
  18. Jim

    Phil Cook Guest

    The Brom front hub isn't the same spacing as the Shimano hub. The SON
    used in the Brom is also designed for 16-20 inch wheels. These days with
    LED lights being protected against over-voltage it doesn't matter what
    diameter the hub is designed for.
     
    Phil Cook, Sep 22, 2011
    #18
  19. Jim

    nmm1 Guest

    Even at Ian's speed and adaptation to drop handlebars, you are
    exaggerating the speed difference due to being upright. At most,
    it's about 10% - not a lot. And it doesn't cause any of the arm
    and neck problems that bedevil many cyclists.

    And that's for riding at a steady 18-20 MPH - in cities, the
    effect is negligible because almost all effort is taken up in
    repeatedly accelerating.


    Regards,
    Nick Maclaren.
     
    nmm1, Sep 22, 2011
    #19
  20. Peter Clinch twisted the electrons to say:
    Briefly I misread that as a dissembling Moulton! Which really did make
    me wonder it was up to! :)
     
    Alistair Gunn, Sep 22, 2011
    #20
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Similar Threads
Loading...