Viewing 36 posts - 1 through 36 (of 36 total)
  • Bromptons….. why?
  • Premier Icon pat12
    Free Member

    …are they so fast?!

    On my daily drag race commute to work i’m often passed by a suited type on a Brompton

    How is this even possible?? they only have tiny wheels!

    (It’s nothing to do with me obviously)

    Goes against everything I think I know about 29ers.

    Premier Icon Nobeerinthefridge
    Free Member

    They have 29cm wheels, so are effectively 29ers? 29er riders seem to be so much faster than the rest of us, this can be the only reason….

    Premier Icon maccruiskeen
    Full Member

    I think theres something in the mindset of Brompton users that makes them want to taunt you by making everything look easy.

    Struggling up  the last few hundred meters of ascent going up Mont Ventoux on a day that was really to windy to have made the trip we were passed by a very smiley Brompton rider wizzing back down with his tie flapping over his shoulder.

    I’ve also chased my Sister in law around sections of Mabie  – her on a Riese and Muller Birdie and heavily pregnant.

    Premier Icon nealglover
    Full Member

    One of the new (quite stealthy) electric ones maybe ??

    Premier Icon mtbqwerty
    Free Member

    They have 29cm wheels, so are effectively 29ers?

    …so metric > imperial

    Premier Icon thisisnotaspoon
    Full Member

    Small wheels are more aero, a few eccentric builders have figured this out over the years so obviously the UCI has banned them.

    That and I suspect an element of Brompton riders riding ~5 miles each way, every day, 47 weeks a year = 2350miles a year, probably quite a lot more than the average weekend warrior, thus they’re actually fitter.

    Premier Icon jameso
    Full Member

    They really aren’t fast. Sorry : ) The suspension squats/bobs under power and those tiny wheels don’t roll very well. But the suspension does smooth things out and they are a nippy (sketchy) ride that encourages speed and acceleration so between the lights I do find it easy to get a decent speed from it. Over a longer distance, 25-30 miles was my limit though some do long audaxes on them, they’re relatively slow ime.

    thus they’re actually fitter.

    Good point, esp if they’re repeatedly accelerating and doing 200m sprints-of-sorts.

    Premier Icon bikebouy
    Free Member

    Once you get past the “bob” they’re reasonably nippy, especially if you stick 100psi in the tyres.

    I used to hate the things for their wild ride and flex, but have over the last few years become accustomed to the generic idiosyncratic weave they have.

    Theres someone on here that does decent upgrades for them, more improvement upgrades than just generic worn out replacements stuff. Can’t remember their name.

    Premier Icon paton
    Free Member
    Premier Icon neilv
    Full Member

    Because they fold…..

    Premier Icon JonEdwards
    Free Member

    Litte wheels = really good acceleration. They’re also so short that they carve really well in traffic. Mine had an incredibly tall top gear too, so once you were wound up to a proper cadence you were carrying some proper speed.

    Mine was a little bit faster on my cross London commute than my fixie, but the fixie is SOOO much more pleasant to ride.

    Schwalbe Kojaks @100psi, firm suspension block (for a <65kg rider, go figure), spds and slightly wider bars. Shame the brakes were truly terrifying, especially in the wet, and the drivetrain was so incredibly agricultural and constantly needing faffing with (3spd Sturmey).

    Premier Icon mariner
    Free Member

    Because they are just fun.
    Been without a proper bike for most of this year and bought my Brompton as a shopper.
    Once I get over the flexing of major components I realised I was actually enjoying riding so now look for excuses to go out.
    Packed my tent and sleeping bag in my bikepacking bags and strapped them on the other day with no bad effects so might give some off road a try.

    The only really downside I have found is the pounding I get if I dont get out of the saddle in time on lumpy tarmac. (Note to self to read up on rear suspension options.)
    New bike frame due hopefully before Christmas so might sell the Brompton but if I do I will be sad to see it go.

    Premier Icon Bez
    Full Member

    The true reason is that Bromptons have such good resale value that if you don’t move quickly someone’ll try and nick it 🙂

    If it makes you feel better, my Brompton doesn’t generally move very fast. Party because I normally can’t be arsed to move it more quickly, but mainly because if you accidentally hit a pothole at speed with a 16″ wheel you’re going to be tossing a coin for ambulance or hearse.

    Premier Icon footflaps
    Full Member

    The true reason is that Bromptons have such good resale value that if you don’t move quickly someone’ll try and nick it

    Just be careful selling on EBay, a friend was buying them from the LBS and selling them overseas via Ebay for a small profit.

    [url=https://flic.kr/p/2hVEEYh]Bromptons[/url] by Ben Freeman, on Flickr

    Premier Icon MTB-Idle
    Free Member

    these three guys were fairly steaming along on the RVV/Tour of Flanders back in April

    Premier Icon chiefgrooveguru
    Free Member

    They’re bloody quick off the line but once you get up to speed they’re an aero nightmare. For short sprints between the lights in London the acceleration outweighs the higher speed inefficiency.

    They’re also extremely intolerant of you letting the tyre pressures drop, they don’t feel good and go much slower, so maybe more likely to be kept pumped up?

    There’s also something amusing about overtaking a proper bike on something so silly looking, a good reason to pedal harder!

    Premier Icon paton
    Free Member

    Moulton used to have a reputation for speed.

    Premier Icon root-n-5th
    Full Member

    It’s funny and against general consensus it appears, but I hate the tings at 100PSI – very skittish and harsh. Much better around 60psi where it softens the ride a bit and absorbs the bumps. They are good for short sprints but a bit of a pain to ride any distance over about 5 miles.

    Premier Icon HoratioHufnagel
    Free Member

    I thought they were quite nippy. Rolling resistance of tyres is minimal when at a decent pressure, the firm suspension block didn’t bob much for my 96kg bulk and the flat bar version has quite a low ish front end.

    The biggest cause of drag is the hub gears IMO, very noticeable, especially in the lowest gear on the 6 speed version I had. 2 speed was much better.

    More than anything though, as above… bikes aren’t fast, riders are.

    Premier Icon jimdubleyou
    Full Member

    I’ve put a super firm suspension block in mine – has pretty much eliminated the bobbing, even for a biffer like me. You lighter chaps should be laughing…

    https://www.sjscycles.co.uk/frames/joseph-kuosac-suspension-block-for-bromptons-super-firm-black/

    I’ve ridden mine 60+ miles on a FNRttC and it was actually ok. The added benefit of not having to squeeze a bike on the train home was also a bonus.

    I think if I was going long distance, I’d be looking at a 6 speed for the extra getting up steep hills options that would give. Turning the three speed up anything steep is not great…

    Premier Icon root-n-5th
    Full Member

    I got the firm block too – much better. Also reversed the saddle clamp so it is higher and further back and put slightly wider flat bars on – it is the 2SL so came with flats. Position is now almost identical to my old Xc style mountain bikes so quite comfy but not too upright.

    The 2 Speed is good as the gear mech is so simple it doesn’t create any real drag. Also lowered the gears somehow – either a smaller chainring or larger sprockets, but can’t remember which.

    Premier Icon Bez
    Full Member

    Just be careful selling on EBay

    Wow. An entire page of a newspaper devoted to an anecdote about someone not realising that “relist” didn’t mean “list something else” and then having their predicament wholly resolved so that everything ended up just as they had originally expected. If that’s not a slow news day I don’t know what is 🙂

    Premier Icon slowoldman
    Full Member

    Struggling up the last few hundred meters of ascent going up Mont Ventoux on a day that was really to windy to have made the trip we were passed by a very smiley Brompton rider wizzing back down with his tie flapping over his shoulder.

    This guy?

    David Millar

    Premier Icon footflaps
    Full Member

    Wow. An entire page of a newspaper devoted to an anecdote about someone not realising that “relist” didn’t mean “list something else” and then having their predicament wholly resolved so that everything ended up just as they had originally expected. If that’s not a slow news day I don’t know what is

    It was in the Money section, so basically pages on anecdotes about refunds for white goods etc and a two line article on how saving rates are crap. Plus he works for the paper…

    Premier Icon simons_nicolai-uk
    Free Member

    I got the firm block too – much better.

    had the firm block as an ‘upgrade’ on my old brommie. New one bought a year ago and there is no longer an open ‘they all come with the firm block now’ but I’d swear its not as firm as the old one.

    This just sounds near solid https://www.sjscycles.co.uk/frames/joseph-kuosac-suspension-block-for-bromptons-super-firm-black/

    RockBros make a ti coil spring to fit (on eBay/Wish etc) and there seems to be other (undamped) coil options

    Premier Icon simons_nicolai-uk
    Free Member

    It was in the Money section

    The ‘what have the idiots done this week’ section as it’s known in our house

    Premier Icon jameso
    Full Member

    Litte wheels = really good acceleration

    Light wheels = really good acceleration, to be a pedant geek : ) Small wheels have to spin faster so the size bit cancels out and only weight really matters.
    And tyre pressure, but agree with

    It’s funny and against general consensus it appears, but I hate the tings at 100PSI – very skittish and harsh. Much better around 60psi where it softens the ride a bit and absorbs the bumps.

    – prefer mine with ~70psi. At 100 it’s pingy, it does feel quicker but whether it really is I’m not sure, if anything the softer tyre should help the small wheel cope on bad roads. Like the Moulton though the suspension block does some of that. It’s one of those bikes that I like because of its quirks, even the flexy stem post feels nice on a longer ride. For me it’s not a fast bike just because I like pootling along on it. Only spin it up if I’m running late for the train.

    Premier Icon Bez
    Full Member

    It was in the Money section, so basically pages on anecdotes about refunds for white goods etc and a two line article on how saving rates are crap. Plus he works for the paper…

    😂

    I remain glad that I never read any newspapers 🙂

    Premier Icon footflaps
    Full Member

    The ‘what have the idiots done this week’ section as it’s known in our house

    I like that!

    Premier Icon aP
    Free Member

    I’ve got a Matumura Kohki Scrowave Suspension Spring on my S2LX. It is low bob and just takes the sting out. Doesn’t go off like the rubber blocks.

    Premier Icon Ben_H
    Full Member

    I ride my Brompton a lot around London when I’m there with work. The Brompton is a great device and has really made me enjoy my visits… I don’t think it’s fast though!

    I ride around London in a suit / tie / work shoes. I guess it’s possible that – because I’m 72kg and ride a fair bit – I have given a few people a fright in my disguise. That said, the sweaty man in a suit look isn’t popular with colleagues.

    Out of curiosity, I took my racey bike to London recently. It was *way* faster where there was a chance to open up. Overall and around the packed streets all I wasn’t really much quicker than on the Brommie though.

    Premier Icon Greybeard
    Full Member

    Light wheels = really good acceleration, to be a pedant geek : ) Small wheels have to spin faster so the size bit cancels out and only weight really matters

    Small does help acceleration. Rotational moment of inertia is mass times radius squared, so spin speed only cancels out one of the squares.

    .

    Premier Icon swedishmetal
    Free Member

    I’ve been toying with getting 2 Bromptons for my wife and I on cycle to work – one per year!

    I don’t really need one but I can’t help thinking they’d be great to take on holidays when we don’t want to take the full bikes and all the kit, plus it might make me ride around town more as I’m over paranoid about cycle theft and you can just take them in anywhere you go.

    I’ve decided I’ll get an S style with guards.

    Question – my wife is quite short at 4’11” and test ride an S Type and found it VERY twitchy. Do they really suit someone her height? Any that can be done to customise them to the shorter person at all?

    Premier Icon sirromj
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    Premier Icon jameso
    Full Member

    Rotational moment of inertia is mass times radius squared, so spin speed only cancels out one of the squares.

    OK, well I’ll not claim to be grade A with mechanics so correct me if I’m wrong here. MOI is is only part of the energy changes in a rolling wheel – total energy in a rolling wheel is rotational + linear energy, rotational energy part is 1/2(MOI)*(Angular velocity)2, where radius is a factor in both MOI and AV, so r cancels (and that was the part I had to look at someone else’s workings on when looking into this size vs rotation speed Q in the past). Linear energy part is 1/2MV2, so total energy simplifies to E=MV2, thf in any situ looking at changing total energy wheel size isn’t a factor, only weight – though of course larger wheels of a type are almost always heavier.

    found it VERY twitchy.

    They are a bit quick-handling but a bag on the front calms it down, as does moving your weight forward and a wider bar. Larger tyres with less pressure also help ime.

    Premier Icon jimdubleyou
    Full Member

    Question – my wife is quite short at 4’11” and test ride an S Type and found it VERY twitchy. Do they really suit someone her height? Any that can be done to customise them to the shorter person at all?

    There’s a woman who rides a Brompton in the Fridays of a similar stature. Don’t think she rides an S – maybe try an M?

    Don’t know where you’re based but the guys in On Your Bike in London Bridge were very helpful when I was deciding what to get.

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