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Old 05-04-17, 12:03 PM   #1
mtb_addict
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Brompton S to M convertion

Hi

I found a cheap but mint Brompton on sale...but it's a S2 model.

The bar is too low for my taste...I don't bend so well.
I like to convert to M.

Besides swapping out the handlebar, stem and the cables...what else?

Wow, this could get expensive.

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Old 05-04-17, 01:14 PM   #2
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... I found a cheap but mint Brompton on sale...but it's a S2 model. ... I like to convert to M. ...
I have sent you a private message. Note that for 2017 Brompton improved the M and H handlebars. Many of the 2016 and earlier components are not interchangeable with 2017 M and H models.


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Old 05-04-17, 01:58 PM   #3
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I have sent you a private message. Note that for 2017 Brompton improved the M and H handlebars. Many of the 2016 and earlier components are not interchangeable with 2017 M and H models.


-HANK RYAN-
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I am pretty sure the bike is pre-2016.

I found a conversion kit for $300. Wow, no longer cheap deal after the cost of conversion!

I think I'll have to pass on this S2.

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Old 05-04-17, 02:27 PM   #4
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Don't pass yet as this is doable because I did it. You keep the S stem, purchase 60 mm riser bars, new cables because of the height and you are ready to go. The total height is very close to the M. I have posted these photos multiple times on here. Someday I will actually measure it and see the how much of a difference there is. My guess maybe 10 mm.






Last edited by blakcloud; 09-05-17 at 02:15 AM. Reason: Photobucket to Flickr links restored.
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Old 05-04-17, 03:06 PM   #5
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Don't pass yet as this is doable
Did you use generic brake/shifter cables?

Or are the cables Brompton proprietary only?

Does that 60mm handlebar allow folding properly?
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Old 05-04-17, 03:28 PM   #6
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The shift cable is Brompton specific so you just buy the M length and it comes with housing.

The brakes are just generic cables and housing. The brake levers I replaced because I like the look better. Ergon grips for comfort.

You have to trim each side of the bar to make it narrower for the fold. I could trim a little more to make it fit a little better but not worth it to me.


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Old 05-06-17, 08:30 AM   #7
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Yea , they charge 1st world money for their parts.. H mast, has the hinge up higher,

so the M bar wont be lower than the ground plane.. when folded down.

although the center clamp is at about the same height as the S Mast.

...
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Old 05-06-17, 03:41 PM   #8
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Originally Posted by blakcloud View Post
The shift cable is Brompton specific so you just buy the M length and it comes with housing.

The brakes are just generic cables and housing. The brake levers I replaced because I like the look better. Ergon grips for comfort.

You have to trim each side of the bar to make it narrower for the fold. I could trim a little more to make it fit a little better but not worth it to me.



this is something I have also done. Not quite as high. Trick is to find the right shape bars, rising immediately from the clamp upwards.

You could also use abber hallo or similar to raise the bar a bit. Done that too.
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Old 05-07-17, 04:47 AM   #9
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Originally Posted by HGR3inOK View Post
I have sent you a private message. Note that for 2017 Brompton improved the M and H handlebars. Many of the 2016 and earlier components are not interchangeable with 2017 M and H models.


-HANK RYAN-
Norman, Oklahoma USA
Well what has changed is the stem height on M + H models, the bar-height and the shifters on all models. What comes along with this is
- a new M/H-bar that is a couple of cms lower than the older to accomodate the higher stem (overall height of the grips is identical)
- new break levers with bolt-ons for the new shifters
- new bell (now bolted onto the right break-lever)
- new gear-cables
- new "dogleg" for the derailleur to accomodate the new shifters
- new handlebar grips (wider and bolted instead of glued)

So it is not really "many components". Furthermore you should be able to fit the new parts to any Brompton since they changed the fork back in 1991 or so - so it is not a huge problem, but you will need rather a combination of parts than just a single one to do the conversion.

What works:
- old stem, old shifters, old grips, old break levers, new bars. You'll end a bit lower than factory M + H
- old stem, old bars, new shifters. You'll need the new dogleg if you are having a dreailleur and new break levers to mount the shifter(s) (one or two, depending on your configuration). Be aware that it is a tight fit on the old M/H-bars and therefor there's less room for the grips than before - your grips probably will have to be cut down. Nothing for the "big-handed". No problem on the S.
- new stem, new bars, old shifters and break-levers.

What doesn't work:
- new M/H-stem, old M/Hbar
- old break levers, new shifters
- new derailleur shifter, old dog-leg
- old M/H-bar, new shifters and levers AND the new Brompton handlebar-grips

The promise of the new factory bar-setup is better stiffness of the M/H-bars and better looking shifters with better usability (a question of taste). However - the stem is pretty expensive if you do not manage to grab a used one.

This is where riser bars and riser stems like the aber-hallo come into play. The problem is that, if your bar has too much height it's left end will hit the ground in folded state, either stopping the possibility to roll the bike in folded state or even to complete the fold (if it is much to high). Factory heights are shown here (old setup, but no change to overall heights with the new model):



As you can see the S is 924mm from the ground (which is the stem-height as well) whereas the M is 1013mm from the ground. Therefor the M is officially ~9cm higher than the S. The old M/H-bar until late 2016 is ~16cm high, therefor the old M-stem is ~853mm (1013mm - 160mm), making it ~70mm lower than the S-stem. With the 2017 stem and bars measurements changed about 30 mm as far as I know: the M- and H-stems are about 3cm higher, the bars about 3cm lower. The S-version stayed the same.

So, to achieve the height of the M you need to rise your bar on the S about 80 - 90mm. You have some buffer space, as the M-Bars have a bit of ground-clearance when folded - maybe 1-2cm.

The Brompton-bars (S as well as M/H) are 53cm wide (apart from early S-bars from 2005 until 2008 which were 48cm wide). So in theory you should be able to mount a 9cm riser bar onto the S, achieving the same height as the M - if you stick with the width of 53cm. If you go for a wider bar your rise will have to be lower (due to folding). The H-stem offers by far the best possibilities for alternative bars as it is 6 cm higher and therefor offers 3cm more ground-clearance in folded state (as the folding hinge on the stem is 3 cm higher than on the other stems).
Please note that the forward angle differs a bit in between the various stems plus you can (and probably will) adjust the angle of the bars to your own taste.

All this will influence the possibilities which bars are possible (even the kind of grips you mount to the bar will and you will probably not be able to use bar-ends any more). From experience is is not totally easy to find a riser-bar that offers the desired maximum height, the more as most bars reach their maximum height on the outer edges but are at the same time wider than the Brompton's 53cm. At 53 cm they will therefor be lower than their nominal height but at the same time it may be the case that cut down to 53 cm (or alike) there will not be enough room left on the straight part for grips, shifters etc. if the rising angle of the bar is relatively modest. This becomes more of a problem the more rise the bars have.

Extenders like the aber-hallo or the trans-x are therefore easier as you can use a straight bar or one with less rise. Downside is (apart from slightly higher cost) the slightly higher weight, the optics and the fact, that those risers require a wider clamping area of the bar than a traditional stem. Something not that many bars offer. Using a Brompton S-Bar with a riser works decently, but the height you reach is limited (it won't be the mx 9 cm). If you are willing to throw in a little bit more money you could look at the Tern Andros-stem. This offers more height compared to aber-hallo and trans-x and you could get a bar that fits from Tern, too.
Some mount a quick-release bolt on top of the Brompton's stem instead of the factory Hex-bolt and manage tis way to be able to fold even with adjustments and bar/riser configurations that would otherwise not work. Something to do at your own risk...

I recently converted a S-Brompton with a bar that offers 8 cm of rise which I found by accident. It is currently 58cm wide and with my ergonomic-grips fitted it is literally mms above the ground in folded state. I'll probably cut it by 1cm on each side as it seems just a little too wide when riding. Furthermore with the current width annoyingly the Brompton cables for the M-model have proven to be a bit too short, too. So finding out the correct cable length is another issue that needs some time and probably some try and error as well. But going custom saves a lot of money in comparison to a stock conversion. You have to pay the equivalent in time though and I'd recommend working slowly and sorrowfully, especially if you are new to the Brompton and therefor lack experience with it. Otherwise you'll end up buying wrong things, cutting cables too short (both canibalizing your savings) or mess up the fold or functionality. This thing is tiny but folding makes it rather complex, especially regarding the cables.

Last edited by berlinonaut; 05-07-17 at 08:56 AM.
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Old 05-07-17, 05:48 AM   #10
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Originally Posted by mtb_addict View Post
Hi

I found a cheap but mint Brompton on sale...but it's a S2 model.

The bar is too low for my taste...I don't bend so well.
I like to convert to M.

Besides swapping out the handlebar, stem and the cables...what else?

Wow, this could get expensive.
Btw: I don't know what you consider cheap and what you consider mint condition. But as the specs for 2017 habe changed with Bromptons (as discussed) at least here in Europe pre 2016 models sell for a considerably reduced price with many dealers as they want to get their stock cleared and the optical differences to newer models are obvious. One of the rare occasions to grab a new Brompton relatively cheap (or at least much cheaper then normal). This has not shown effect to prices of used bikes yet. You should keep this in mind when judging on the price of the one offered to you, especially as it does not have the handlebars that you want, adding follow-up-cost. As it is not a 2017-model: Does it have the 2013 spec (newer break-levers, changeable chain wheel etc.)? If not the price should be again a bit lower then. And an brandnew 2013-2016 spec with the disired bars could maybe be an alternative (depending on the dealers in your area of the world).
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Old 05-07-17, 01:04 PM   #11
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... So it is not really "many components". ...
Thank you for your thorough explanation. I think we are addressing the same consideration. Perhaps you would be more comfortable with "some components". I am not comfortable saying "a few components".


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Old 05-08-17, 04:11 AM   #12
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Thank you for your thorough explanation. I think we are addressing the same consideration. Perhaps you would be more comfortable with "some components". I am not comfortable saying "a few components".


-HANK RYAN-
Norman, Oklahoma USA
Well I'd be ok with "some" as well as with "few". What I am uncomfortable with is more:

Quote:
Many of the 2016 and earlier components are not interchangeable with 2017 M and H models.
I think this is wrong. You cannot use the 2016 and earlier M/H bars on 2017 M/H-models when keeping the 2017 stem, this is the only part that is not interchangeable and only in combination with the 2017 stem - using the 2016 stem is possible on 2017 models (but who would want to do that anyway?) - everything else will work. So even "few" would be wrong here.

The other way round is more interesting: If you want to use 2017 components on 2016 and earlier bikes you'll typically have to upgrade rather a set of parts instead of a single one. Fair enough. Complaining about that would be the same as complaining that you'll have to buy a new, slimmer chain if you upgrade a derailleur from 7-speed to 10-speed or a new shifter if you upgrade from a 3-speed to a 5-speed hub. Brompton is famous for backwards compatibility - being able to retrofit newer components to older bikes is something that has always been possible and still ist. Plus you are still able to get older, incompatible parts years later (as i.e. the sprinter shifter), so there's in my eyes nothing to enhance here with Brompton's approach - it is lightyears better/more userfriendly than most of the rest of the industry anyway.
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Old 05-08-17, 08:45 AM   #13
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... Complaining about that would be the same as complaining that you'll have to buy a new, slimmer chain if you upgrade a derailleur from 7-speed to 10-speed or a new shifter if you upgrade from a 3-speed to a 5-speed hub.
FWIW, I am not "complaining".
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Brompton is famous for backwards compatibility - being able to retrofit newer components to older bikes is something that has always been possible and still ist. Plus you are still able to get older, incompatible parts years later (as i.e. the sprinter shifter), so there's in my eyes nothing to enhance here with Brompton's approach - it is lightyears better/more userfriendly than most of the rest of the industry anyway.
I wholeheartedly agree. I was trying to inform the OP that a one-to-one parts swaps between 2017 and pre-2017 parts are not always possible. (For example, the new grips for 2017 will not work on pre-2017 M and H bars.)

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Old 05-19-17, 06:00 PM   #14
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Originally Posted by mtb_addict View Post
Hi

I found a cheap but mint Brompton on sale...but it's a S2 model.

The bar is too low for my taste...I don't bend so well.
I like to convert to M.
But a smaller model is probably lighter. That may be an advantage for some.
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Old 09-01-17, 01:16 AM   #15
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Handlebar and stem change

That is true. The handlebars from 2016 and 2017 are different… Take a look here to have an idea of the change: or look in google for it there are many photos of this change around.

I own a 2017 Brompton bike version and am very satisfied with this change. The bike handling is great, go try it for your self on a shop!

Take special attention to accessories that fit well the 2016 but may not work that well on the 2017 handlebar, since the handlebar is shorter the stem was changed also to compensate (bigger). If one uses the new handlebar with the old stem probably the folding process gets compromised but I am not sure about this…
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Old 09-02-17, 01:44 PM   #16
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2 speed is a lighter hub + the chain shover with the lever on the left.

tried just putting a bit of a riser bar on it yet?
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