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  1. #1
    nun
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    Brompton derailleur.

    I've caught the folding bug and I'm considering a six speed Brompton and a Tern Link P9. Obviously the Brompton folds smaller, but I look at the gearing set up and only it could have been designed in England (I'm English so I can say that). Is that a plastic derailleur? I like the Tern because it uses pretty standard modern bike components and I can see myself customizing it easily.

    So what are your opinions about the Brompton parts, they seem pretty old fashioned and has anyone had issues with that flimsy looking derailleur system?

  2. #2
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    It's only a device to switch between 2 sprockets, I think plastic is fine for that. Brompton like their plastic and it makes sense given that the steel frame is heavy.

  3. #3
    nun
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    Quote Originally Posted by chagzuki View Post
    It's only a device to switch between 2 sprockets, I think plastic is fine for that. Brompton like their plastic and it makes sense given that the steel frame is heavy.
    Yes I realize that. It seems strange to try to save weight with plastic components when the frame would be the place to do it. I worry about the durability of the plastic and the design choices that lead to it. I also see that Bromptons still have cup and cone bearings and the fiddling required to get the rear wheel off cancels out the elegance of the fold IMHO. I'm also looking at the Tern verge x10 as I like the low weight and the reviews say it rides very well. The fold isn't as nice as the Brompton, but it's probably good enough and I can mess around with the gearing as much as I want and change out wheels easily.

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    I recently purchased a BRompton and had the same concerns as you. However cheap the components appear they seem quite durable and function very well. The whole bike is designed around the perfect fold so you will have to settle for all the quirkiness and compromises resulting from this perfect fold. The hassle with removing the rear wheel cannot be overlooked and is a serious consideration if you are looking at this bike for something more than local commuting. However, this is my philosophy: If I were to get a rear wheel flat I can elect to call a taxi or have someone pick me up in a car and fix it later in a more ideal environment. This is why I have chose to use Marathon tires instead of less puncture resistant Kojaks. Since spare parts are for the most part Brompton-specific, I would make an effort to collect as many spare parts as possible for fixes on the road or at home. I have found that the advantages of the excellent fold out weight the disadvantages of the bikes quirks. And quite frankly, I have been pleasantly surprised at how comfortable and fast this bike rides due to the high pressure tires and smooth running wheels.

  5. #5
    Senior Member kamtsa's Avatar
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    Quote Originally Posted by nun View Post
    So what are your opinions about the Brompton parts, they seem pretty old fashioned and has anyone had issues with that flimsy looking derailleur system?
    Yes, highly proprietary bike, old fashioned, pastic parts, and not best looking IMO. However it's my bike of choice after using BF NWT, Moulton TSR, and Dahon. Somehow it just works well all around. It also has excellent spare part availability and long term support. You can order spare parts and upgrade kit online by SKU http://www.sjscycles.co.uk/brompton-shopbrompton_pg1/

    If you are test riding a Bromton, make sure to try both M and S handlebars. They provide very different ride experience.
    Happier than a camel on wednesday.

  6. #6
    coprolite fietsbob's Avatar
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    Brompton took an alternate approach in their rear 'derailleur',
    since the change is just A/B, rather than over complicate a simple task, .. k.i.s.s.
    they engineered the pulley to incorporate guide flanges, to keep the chain on the pulley.
    then a simple fork like lever pushes that pulley, itself , directly sideways.

    I use the Sachs 15 t, it fit my AW3.. 3 teeth are shorter for a shift gate.

    Some custom builders, like Steve Parry in the UK, have made a bracket to put a FD on
    of a braze-on type, and then an additional lever is added to the handlebars.

    that is more practical as a range shift, rather than a half step,
    the BWR hub is wider ratio than the AW3/BSR hub, ant the 13/15t cog set half steps that.

    Older Mk3 bikes got Sachs to make the 3 by 2 hub, its a narrower ratio spaced hub,
    its 'cassette' uses the AW type cog ,
    spares of the thinner cog , for 3/32 chain, can be useful. Vs 1/8" , thicker cog..

    I sense their use of plastics, chosen, mold design for the materials,
    are well designed, and robust .

    the chain-tension arm is a pretty solid piece..

    I have a M3L, I use a 2 speed Schlumpf Mountain drive crank
    instead of a front derailleur,
    To increase my climbing capabilities, 6 speeds in a widely spread pattern
    the 3rd to 4th is both a hub gear and a crank range double shift,

    but being both planetaria, that shift can happen at any speed,
    so the bogged down in low while in high range, is no problem,
    to shift to .. high in hub, low range in the crank, the next lower ratio.
    Last edited by fietsbob; 02-14-12 at 06:41 PM.

  7. #7
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    Quote Originally Posted by nun View Post
    Yes I realize that. It seems strange to try to save weight with plastic components when the frame would be the place to do it. I worry about the durability of the plastic and the design choices that lead to it. I also see that Bromptons still have cup and cone bearings and the fiddling required to get the rear wheel off cancels out the elegance of the fold IMHO. I'm also looking at the Tern verge x10 as I like the low weight and the reviews say it rides very well. The fold isn't as nice as the Brompton, but it's probably good enough and I can mess around with the gearing as much as I want and change out wheels easily.
    The Brompton frame is too heavy IMO, really. I don't know much about steel tubing but from what I gather Brompton uses straight gauge high-tensile steel. . . someone can fill me in on whether this is the right choice in design terms. I guess there's only scope for butted tubing on the rear frame, but surely some form of chromoly steel would result in a much lighter bike. But high-ten is cheap and Bromptons sell for big figures so I guess that's nice for them, and not for me. As for the use of plastic I tend to think it works well. The seat post q/r lever, for example, feels nice in plastic and it's preferable to e.g. the lower-end Dahons that have hard-edged alloy q/r levers. Not that it makes much difference. Brompton use plastic for the seat post shim, Dahon aluminum. It's arguable which is better, but Dahon's version innevitably scratches the seat post, abrades it over time, so I like plastic there too. The individual parts of the chain tensioner are available as spares so if you bust one you probably don't even have to buy the whole thing again. . . Brompton are good like that.

    Cup & cone hubs are fine with me though Brompton do have a super-light front hub that I'm sure has sealed bearings, and is rather over-priced compared to the nice Dahon/Tern equivalent.

    If you're riding longer distances and like to pull on the handlebars then I'd say the Tern would ride far better. Bromptons are flexy and have an odd gearing system, fine for shorter distances. If you like comfort then you may find a Tern harsh without some form of rear-end suspension, a sprung saddle etc.. I like Brompton's rear suspension.

  8. #8
    coprolite fietsbob's Avatar
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    You might invest in the 'kickstarter' thing for the UFB,(ultimate folding bike) which needs capital..
    an all Titanium Bike , based on the Brompton frame design.. target price : $10K each.

    so far Len Rubin's [IT gigs] .. money got only a prototype or 2.. made.
    Last edited by fietsbob; 02-14-12 at 10:13 AM.

  9. #9
    Senior Member snafu21's Avatar
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    Cup-N-cones have provided a gazillion miles of trouble free bicycling for squillions of cyclists.The trick with those on the Bromptun is to re-grease them properly when the bike is new. Grease seems to be charged for by the inch at the Brompton factory.

    The bottom bracket is sealed though, should you feel a need for new-fangled apostasy.

    I should add, that you might try to hire or borrow one for a day. I hated mine utterly, but 500,000 Londoners cannot be wrong.
    Last edited by snafu21; 02-14-12 at 10:34 AM.
    - every mile of road has two miles of ditch -

  10. #10
    nun
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    Quote Originally Posted by chagzuki View Post
    If you're riding longer distances and like to pull on the handlebars then I'd say the Tern would ride far better. Bromptons are flexy and have an odd gearing system, fine for shorter distances. If you like comfort then you may find a Tern harsh without some form of rear-end suspension, a sprung saddle etc.. I like Brompton's rear suspension.
    I've done a lot of riding on regular steel bikes with skinny tyres so I'm coming at this from that perspective rather than someone who is relatively new to riding and looking for a convenient commuter. I love the practicality and fold of the Brompton, and the weight and use of components on the Tern X10. I'll be doing some commuting and light touring on the bike so I think I'll go with the Tern. I'll put a Brooks on it, get an extra set of beefier wheels for touring and get lower gearing by using a smaller front ring. The Tern's font luggage carrier also fits my Ortlieb front bag

  11. #11
    nun
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    Cup-N-cones have provided a gazillion miles of trouble free bicycling for squillions of cyclists.The trick with those on the Bromptun is to re-grease them properly when the bike is new. Grease seems to be charged for by the inch at the Brompton factory.

    The bottom bracket is sealed though, should you feel a need for new-fangled apostasy.

    I should add, that you might try to hire or borrow one for a day. I hated mine utterly, but 500,000 Londoners cannot be wrong. I should add, that you might try to hire or borrow one for a day. I hated mine utterly, but 500,000 Londoners cannot be wrong.
    Sure cup and cone is fine, I packed grease in many of them when I was a teenage acolyte . However, I think the Tern makes nice use of standard bicycle components and as I'm polytheistic now I like to be able to mix and match. If I'm on a tour and have a mechanical problem it's good to be able to go into any bike shop and buy something from Shimano or SRAM and just install it. If commuting and trips on the Tube were all I was doing, then the Brompton's fold might make it the better choice, but I think I'll go with the greater versatility of the Tern and sacrifice a bit on the fold.
    Last edited by nun; 02-14-12 at 10:47 AM.

  12. #12
    Senior Member kamtsa's Avatar
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    Quote Originally Posted by nun View Post
    Sure cup and cone is fine, I packed grease in many of them when I was a teenage acolyte . However, I think the Tern makes nice use of standard bicycle components and as I'm polytheistic now I like to be able to mix and match. If I'm on a tour and have a mechanical problem it's good to be able to go into any bike shop and buy something from Shimano or SRAM and just install it. If commuting and trips on the Tube were all I was doing, then the Brompton's fold might make it the better choice, but I think I'll go with the greater versatility of the Tern and sacrifice a bit on the fold.
    Looks like you found the right folder for you. Don't forget to post pictures when you get it ;-)
    Happier than a camel on wednesday.

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    The Verge X10 looks like a work of art. Probably too stiff for me, I'd need fatter tyres & a thudbuster as small wheels don't like rough terrain much.

  14. #14
    nun
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    Quote Originally Posted by kamtsa View Post
    Looks like you found the right folder for you. Don't forget to post pictures when you get it ;-)
    Yes, will do. Another factor for me going for the Tern is the 20" wheels which I hope will be a bit better on the bumps than 16" wheels. The X10 and a 6 speed
    Brompton are basically the same price and I just can't bring myself to pay that much for a bike with a that Stronglight crank when on the X10 I get an FSA Gossamer. This is important to me, but may not be of concern to most people looking for a folding bike where a small fold is the driver. I'll be using the X10 on longer rides and will fold it when I use public transportation or fly on a plane.....it'll fold small enough for that and I think I'll enjoy the riding a bit more.
    Last edited by nun; 02-15-12 at 09:17 AM.

  15. #15
    PDR
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    Ok, this is my personal experience of a 2009 Brompton S-Type, 2 speed titanium (lightweight) raw lacquer.

    To set the scene, I bought a Dahon MU SL in 2008 after trying a range of different folders (including Bromptons). Within months that first Dahon was exhibiting serious play in the frame hinge to the point you could see and feel the bike flex in the middle when riding it or lifting the bike. The bike also creaked from the seat post and the clamps needed checking regularly. The bike was sent back and replaced under warrantee. This time I knew what to look for.... and yes, sure enough the same frame wear problem became evident, along with the stupid creaks and groans. One other aspect of these bikes is that the paint is very prone to scratching and chipping. That second 2008 model MU SL was sent back under warrantee and and this time I was sent a 2009 model with supposedly improved main hinge.... as I unpacked the bike I was shocked to see that there was a big chunk of metal missing from the hinge plate... weather this was important in regards to strength or just a cosmetic defect was not the issue, that bike should not have got through quality control... these where top end, expensive models remember. That bike was sent back and I was given a refund... good riddance Dahon, NEVER again!!!

    So this leads me to my custom ordered Brompton which I will have had 3 years next month. The bike has been used daily all year round for my commute to work (via train) and I use it at weekends for rides into the city. My Brompton has performed flawlessly, no squeaks, creaks or rattles. It still rides like a new bike. The only parts I have replaced are one set of brake block (inserts) and a change of tires. I switched to Kojaks, these have lasted well but I have a new set to put on once the Spring arrives. Cosmetically the only signs of wear is one of the standard foam handlebar grips is a bit tatty (the one that is nearest the ground when the bike is folded) and the "Brompton" frame sticker has a couple of scuffs.... but I have ordered spare grips and frame decals and will fit them along with the new Kojaks once Spring is finally here. The raw lacquer frame and titanium parts still look as good as new, the raw lacquer finish seems very resistant to marking. I fitted a Brooks Swift Titanium saddle and a set of Brompfication custom Brass frame clamps.

    People say that Bromptons are the one of the few folding bikes that owners fold consistently.... mine is stored folded at home, at work and for every train journey (the hinge plate clamps / bolts are of course "self adjusting" )..... whereas I hardly see Dahon owners fold their bikes for train travel.... there is a University academic I know with a Dahon MU SL and I have never seen him fold it, oh and yes, he had to get the bike sorted out under warrantee for the same frame failure

    As regards the components on the Brompton, they have proved to be reliable and very durable.... and they are of course readily available (try getting spares for a Dahon ) Some parts might look "cheap" (I thought the brake levers looked nasty the first time I saw a Brompton) but everything just works! I read in another post about "all roads lead to Brompton" and I can understand that! I wasted money and time on Dahons ... but at least I learnt a lesson... I learnt to appreciate just how wonderful my Brompton really is!
    Last edited by PDR; 02-16-12 at 02:28 AM.

  16. #16
    nun
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    Quote Originally Posted by PDR View Post

    As regards the components on the Brompton, they have proved to be reliable and very durable.... and they are of course readily available (try getting spares for a Dahon ) Some parts might look "cheap" (I thought the brake levers looked nasty the first time I saw a Brompton) but everything just works! I read in another post about "all roads lead to Brompton" and I can understand that! I wasted money and time on Dahons ... but at least I learnt a lesson... I learnt to appreciate just how wonderful my Brompton really is!
    The Brompton parts may well be durable and Brompton does seem to have a good stock. I've read many comments from happy Brompton owners, so they are doing something right. But I look at the gear shifters and the rear derailleur and I just can't bring my self to buy one. I'm being a snob, but I know the first thing I'd do would be to switch out the plastic shifters for a better quality SA version. The Brompton is well designed for commuting, but would not be good for the longer rides and ease of repair that I want.

    The issues with the Dahon sound annoying, but I'm looking at the Tern which has redesigned hinges and posts. I'll post my impressions of the Verge X10 when I get it.
    Last edited by nun; 02-16-12 at 06:26 AM.

  17. #17
    PDR
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    I do understand what you say nun. I have the simple 2-speed version (I wanted a light and simple stripped down bike)... the 6-speed with 2 gear changing levers seems a little awkward to my mind....

    But having said that, there are a few people doing various conversions which include different gear shifters etc. The basic bike is a good strong design The Dahon MU SL had some great spec components but the frame :roll eyes: Another interesting fact is that both the Dahon and Brompton where very a similar weight yet the time taken to ride the 4 miles back from the station was exactly the same despite the Brompton only having 2 gears verses the Dahon's 9.

  18. #18
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    Quote Originally Posted by PDR View Post
    Another interesting fact is that both the Dahon and Brompton where very a similar weight yet the time taken to ride the 4 miles back from the station was exactly the same despite the Brompton only having 2 gears verses the Dahon's 9.
    Guess they are the 'right' 2 gears!

  19. #19
    coprolite fietsbob's Avatar
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    NB
    With the non IGH OEM Brompton Hub, bike comes with a 12/16 cog set,
    using the 54t crank.

    The BWR comes with a 13/15 .. same spline, 50t the standard crank there.
    BMX Shimano pattern I believe .. SA's S3X might be same..

    If you got the Sachs/SRAM 3 speed , the 13/15t set on those is the AW3 spline/
    Spares of those are handy , I use a 15t on my AW3/BSR.
    Last edited by fietsbob; 02-16-12 at 09:29 AM.

  20. #20
    nun
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    Quote Originally Posted by PDR View Post
    I do understand what you say nun. I have the simple 2-speed version (I wanted a light and simple stripped down bike)... the 6-speed with 2 gear changing levers seems a little awkward to my mind....

    But having said that, there are a few people doing various conversions which include different gear shifters etc. The basic bike is a good strong design The Dahon MU SL had some great spec components but the frame :roll eyes: Another interesting fact is that both the Dahon and Brompton where very a similar weight yet the time taken to ride the 4 miles back from the station was exactly the same despite the Brompton only having 2 gears verses the Dahon's 9.
    We are on the same page here. The Brompton has all the advantages and disadvantages of a classic much loved design. It performs well and Brompton have refined it over the years rather than putting out lots of design changes every year like Dahon. Both approaches have their pluses and minuses. I wouldn't buy one of the less expensive Dahons, but all the noise about the Terns looks positive.

    Gearing can be a complete non-issue in certain terrain and in the city. I once rode from London to Middlesbrough on a 2 speed bike using 67" and 38" and I don't think I'd have done it any quicker or more easily with 27 gears because there wasn't much climbing. When gearing is important it's mostly range and not number or spacing, unless you are racing.

  21. #21
    Senior Member kamtsa's Avatar
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    Quote Originally Posted by nun View Post
    The Brompton parts may well be durable and Brompton does seem to have a good stock. I've read many comments from happy Brompton owners, so they are doing something right. But I look at the gear shifters and the rear derailleur and I just can't bring my self to buy one.
    Follow your heart.

    Selecting a folder is 72% subjective and whatever you will buy will not be your last folder anyway. ;-)
    Happier than a camel on wednesday.

  22. #22
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    There was a horrendous hinge defect with 2008 Dahons, they didn't clamp properly at all. The bikes were junk.
    The Brompton hinge was designed with wide manufacturing tolerances in mind (as with nearly all things Brompton); they opted for a concave plate that alleviates the need for precision-machining as they only touch on the outer edges (the result is that they act as springs and flex). With Dahon you get CNC machined hinge plates that are supposed to fully buttress against each other resulting in much more stiffness so long as the latch is correctly adjusted. With that much greater surface area contact you get more friction if those surfaces should fractionally slide against each other, hence the tendencies of Dahons to creak somewhat once the powdercoat abrades and aluminium rubs on aluminium.

    On the Tern forum there are reports of creaking so it seems they haven't eliminated it entirely. But if you want stiffness the Brompton hinge design won't do.

  23. #23
    nun
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    Quote Originally Posted by chagzuki View Post
    There was a horrendous hinge defect with 2008 Dahons, they didn't clamp properly at all. The bikes were junk.
    The Brompton hinge was designed with wide manufacturing tolerances in mind (as with nearly all things Brompton); they opted for a concave plate that alleviates the need for precision-machining as they only touch on the outer edges (the result is that they act as springs and flex). With Dahon you get CNC machined hinge plates that are supposed to fully buttress against each other resulting in much more stiffness so long as the latch is correctly adjusted. With that much greater surface area contact you get more friction if those surfaces should fractionally slide against each other, hence the tendencies of Dahons to creak somewhat once the powdercoat abrades and aluminium rubs on aluminium.

    On the Tern forum there are reports of creaking so it seems they haven't eliminated it entirely. But if you want stiffness the Brompton hinge design won't do.
    Interesting. The Tern design obviously tries to stop flex in any direction with it's interlocking surfaces. When I looked at the Brompton hinge I liked it's simplicity, but understood the flex issues. I seems to me a good place to use a spherical washer type thing to fill in the gap, but if they are only machining to +/- 0.3mm getting close mating surfaces wouldn't be possible
    Last edited by nun; 02-16-12 at 10:48 AM.

  24. #24
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    I'm guessing that it's something to bear in mind when you get your Tern, make sure the hinges are correctly tensioned from the very start. Not sure sure how exactly you do that, but if there's any sign of the latches being a bit too free then adjust them, and perhaps you'll eliminate any slight slippage that wears away the powdercoat and ends with creaks.
    I realize now that my Dahon frame latch would have been better off being slightly tigher from the start, but there was no play or looseness to indicate it should have been. Just that it developed creaks which I suppress with a bit of grease. Which attracts dirt and abrades the powdercoat no doubt. Oops.

  25. #25
    nun
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    Quote Originally Posted by chagzuki View Post
    I'm guessing that it's something to bear in mind when you get your Tern, make sure the hinges are correctly tensioned from the very start. Not sure sure how exactly you do that, but if there's any sign of the latches being a bit too free then adjust them, and perhaps you'll eliminate any slight slippage that wears away the powdercoat and ends with creaks.
    I realize now that my Dahon frame latch would have been better off being slightly tigher from the start, but there was no play or looseness to indicate it should have been. Just that it developed creaks which I suppress with a bit of grease. Which attracts dirt and abrades the powdercoat no doubt. Oops.
    http://www.ternbicycles.com/support/...tern-ocl-joint

    Maybe try some dry lube rather than grease

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