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Brompton handlebar Stem Question

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Brompton handlebar Stem Question

Old 07-11-20, 01:13 PM
  #1  
ukny
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Brompton handlebar Stem Question

So I have an opportunity to acquire a Brompton.. only thing is it has the M style bars.
I really want S style. If I put a mid rise bar like the Joseph Kousac one will that screw my geometry or is this a good solution without investing in a new stem.. Any opinions / experience / Tips ?? Oh it's a 2016 model.. ( I am not worried about adjusting cable lengths I have a fully equipped work bench..)

Thanks gang..
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Old 07-11-20, 03:14 PM
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Steering geometry remains unchanged.. 72.4 for all
see chart. (Pre 2017) for bar height and the bend offset


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Old 07-11-20, 05:16 PM
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Hmm yep but looking at that graphic the S stem results in a 31 mm longer virtual top tube... I guess setting the saddle back a bit could compensate... I wish I could find a real Geo chart for the Brompton. I might have to be the guinea pig on this one..
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Old 07-11-20, 05:25 PM
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a few simple tools: angle finder @ builders supply & double scale tape- measure & you can DIY the info..

I've had 2 M3 R & L. green one is current ..


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Old 07-11-20, 06:00 PM
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"a few simple tools: angle finder @ builders supply & double scale tape- measure & you can DIY the info.."

Er yeah but you have to have a Brompton to take the measurements from... If I had a Brompton I would not be asking about GEO on this forum,,,
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Old 07-12-20, 07:17 AM
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I have not done this but you may need to change cable lengths. I changed an M to H and had to get new cables. I have heard that you won't need to do this online but cables are fussy when it comes to folding.
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Old 07-12-20, 09:27 PM
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Originally Posted by ukny View Post
So I have an opportunity to acquire a Brompton.. .....
This is quite a popular application for Joseph Kuosac mid riser bar on Bromptons.

You got to keep the cables unchaged (can be a little bit longer for the perfectionist), a lower riding postion (might not be as low as S type) and a very large handlebar (can be 600mm fulll length uncut) for cockpit.

BTW, Joseph Kuosac also has carbon midriser handlebar and the soon to be released carbon ergonomic S handlebar too

This one is from older M to mid-riser Joseph Kuosac uncut

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Old 07-12-20, 10:34 PM
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Thanks thats exactly what I wanted to know.. I actually did a little guesstimating using the published bar heights and it looks like using a 60mm rise bar.. like a BMX bar would put me right at the same height as the S.. just with the shorter virtual TT
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Old 07-14-20, 02:24 AM
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Originally Posted by ukny View Post
Hmm yep but looking at that graphic the S stem results in a 31 mm longer virtual top tube... I guess setting the saddle back a bit could compensate... I wish I could find a real Geo chart for the Brompton. I might have to be the guinea pig on this one..
you could fit a syntace bar adaptor like dahons and terns. it would allow you some extension and rotational tuning
https://www.syntace.com/en_GB/produc....4-clamps?c=79

or a litepro copy
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Old 07-14-20, 02:43 AM
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Originally Posted by Schwinnsta View Post
I have not done this but you may need to change cable lengths. I changed an M to H and had to get new cables. I have heard that you won't need to do this online but cables are fussy when it comes to folding.
it makes sense as you went for something longer and you needed to restore clearances/play for the cable to fold
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Old 07-14-20, 06:51 AM
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Solved

I found these videos on YouTube that have the measurements.. so can work from there..

https://www.youtube.com/c/Bikesandli...y=measurements
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Old 07-14-20, 06:24 PM
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You got some oddly complex answers to your simple question. No there won't be a massive change, the bars will just be a bit lower.
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