# Tech advice...Brompton M6L



## FolderBeholder (26 Jan 2019)

The Missus’ M6L has developed some play in the headset bearing. The steerer/can move to and fro a bit so im think the bearings need adjust. Can I simply unjam the 2 36mm rings from one another and snug-up the lower ring to properly seat the bearings into the races to take up the play? 

Or....does the stem need to be removed first?

Any one? TIA


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## Yellow Saddle (26 Jan 2019)

No need to remove the stem.


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## wisdom (26 Jan 2019)

Yellow Saddle said:


> No need to remove the stem.


Can I simply unjam the 2 36mm rings from one another and snug-up the lower ring to properly seat the bearings into the races to take up the play? 

That should do it.
Grease them at the same time is what I would do.


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## Yellow Saddle (26 Jan 2019)

wisdom said:


> Can I simply unjam the 2 36mm rings from one another and snug-up the lower ring to properly seat the bearings into the races to take up the play?
> 
> That should do it.
> Grease them at the same time is what I would do.


Yes. Grease and clean is always a good idea, although it is impossible to clean them without removing the stem and disassembling the headset.


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## FolderBeholder (26 Jan 2019)

wisdom said:


> Can I simply unjam the 2 36mm rings from one another and snug-up the lower ring to properly seat the bearings into the races to take up the play?
> 
> That should do it.
> Grease them at the same time is what I would do.


Thank you for the info...(the bike is a 2018 model, purchased new and delivered in July of 2018 so I will check the grease but it shouldn’t really need it yet but then so shouldnt the headset bearings need attention) should I be wary of loose ball-bearings?


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## Yellow Saddle (26 Jan 2019)

FolderBeholder said:


> Thank you for the info...(the bike is a 2018 model, purchased new and delivered in July of 2018 so I will check the grease but it shouldn’t really need it yet but then so shouldnt the headset bearings need attention) should I be wary of loose ball-bearings?



If it is that new and hadn't been ridden in the wet, the grease should be fine. No, don't worry about loose ball bearings. They have their advantages, and disadvantages.

Go for a ride and drink a beer.


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## FolderBeholder (26 Jan 2019)

Yellow Saddle said:


> If it is that new and hadn't been ridden in the wet, the grease should be fine. No, don't worry about loose ball bearings. They have their advantages, and disadvantages.
> 
> Go for a ride and drink a beer.


Beer!?


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## 12boy (26 Jan 2019)

When it is shot, Chris King Gripnuts are nice, virtually maintenance free.


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## FolderBeholder (26 Jan 2019)

12boy said:


> When it is shot, Chris King Gripnuts are nice, virtually maintenance free.


I like those as I appreciate that type of craftsmanship and design....we’ve had these bikes just a few months though. The Bromptons have been rock-solid otherwise and we ride them almost daily.


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## berlinonaut (27 Jan 2019)

FolderBeholder said:


> Thank you for the info...(the bike is a 2018 model, purchased new and delivered in July of 2018 so I will check the grease but it shouldn’t really need it yet but then so shouldnt the headset bearings need attention) should I be wary of loose ball-bearings?



It seems to be a bit of a common pattern of the headset coming loose on new Bromptons after a couple of months (or rather a couple of 100 kms). I had this on most of my own Bromptons and know a lot of people having had the same issue on theirs, though not everybody seems to be affected. I assume that the bearing carrier wears in a bit, at least this seems a logic explanation (though I never had that issue with any other bike using the same style of headset). Typically adjusting it once (or in rare cases two or three times) solves it basically forever. As with most people it seems to show up some time during the first year I'd assume it to be less of a time issue but depending from the distance ridden and maybe the surfaces involved as well. Possibly this is one of the topics that the free first service after three months targets at (which obviously only works if until then the bike has been ridden sufficiently for the effect to take place). So nothing to worry about.


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## Kell (27 Jan 2019)

Mine is in constant need of a little tighten every few weeks.


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## rogerzilla (27 Jan 2019)

They're not the best headsets, and I'm not sure Brompton do a good job of facing the head tube and fork crown at the factory, since this is the usual reason for a headset not being able to be adjusted properly. Unfortunately it's also a rather low stack height and therefore not many 1 1/8" threaded headsets will fit. I have a King 2Nut on mine but I had to cheat and grab 1.5mm more stack height by having the head tube aggressively faced.

The other fault these suffer from, at high mileage, is stretching of the head tube. I had an L3 that was about 9 years old, and the lower cup was very loose. Beware of any bike with pressed-in cups that isn't lugged or doesn't have reinforcing rings brazed around the top and bottom of the head tube! I fixed it with a suitable strong grade of Loctite.

Add it to the list of Brompton design faults they still haven't fixed after 30 years...

You should be able to adjust it without removing the stem, if the stem has been fitted properly according to Brompton's instructions. There should be a little daylight between the bottom of the stem and the locknut. If someone has pushed the stem right down when fitting it, you will not be able to undo the locknut without first pulling the stem up a bit. The stem wedge can take quite a hammer blow to make it drop.


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## 12boy (27 Jan 2019)

Rogerzilla, do you suppose the headset stretch could have been avoided if the headset hadn't loosened, or did this happen after you installed the King?


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## berlinonaut (27 Jan 2019)

Kell said:


> Mine is in constant need of a little tighten every few weeks.


In this case I'd assume that the tightening does possibly not happen properly enough in terms of securing the two nuts of the headset against each other.


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## rogerzilla (28 Jan 2019)

12boy said:


> Rogerzilla, do you suppose the headset stretch could have been avoided if the headset hadn't loosened, or did this happen after you installed the King?


It was a different Brompton to the one wirh the King. I think it was just caused by high mileage. It's a known issue with lugless frames.


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## Kell (28 Jan 2019)

berlinonaut said:


> In this case I'd assume that the tightening does possibly not happen properly enough in terms of securing the two nuts of the headset against each other.



That is undoubtedly the case. 

I only ever seem to notice it when I'm on the train and rocking the back back and forth while waiting to get off. 

So I only ever bend down and tighten it by hand. It's certainly not an exact science. 

I also wonder if those of us that have pushed our seats all the way back might experience it more due to the extra weight on the bars.

I also, also wonder that it could be down to the excessive vibrations Bromptons get. If you've ever tried to cycle no-handed on a Brompton, you'll find the bars vibrate alarmingly.


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## berlinonaut (28 Jan 2019)

Kell said:


> That is undoubtedly the case.
> I only ever seem to notice it when I'm on the train and rocking the back back and forth while waiting to get off.
> So *I only* ever bend down and *tighten it by hand*. It's certainly not an exact science.



Oh my. In this case your statement some posts earlier...


Kell said:


> Mine is in constant need of a little tighten every few weeks.


...is massively misleading at best as it suggest this would be due to a lack of quality of the Brompton headset. In fact it is due to improper handling and maintenance. Tighten it properly once and chances are that there is no need to do this exercise ever again.



Kell said:


> I also wonder if those of us that have pushed our seats all the way back might experience it more due to the extra weight on the bars.



Not really. If you tighten it properly once there will be no issue any more, no matter where your seat sits.



Kell said:


> I also, also wonder that it could be down to the excessive vibrations Bromptons get. If you've ever tried to cycle no-handed on a Brompton, you'll find the bars vibrate alarmingly.



No, it is due to improper maintenance. Did I mention that already?  I hope you do a better job on your wheel nuts, let alone your brakes...


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## Kell (29 Jan 2019)

Yes and no. 

I’ve had my Brompton three years and am constantly improperly tightening it. 

My last bike was a Dahon which I had for for five years. 

Not once did the headset need tightening.


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## berlinonaut (29 Jan 2019)

Kell said:


> Yes and no.
> I’ve had my Brompton three years and am constantly improperly tightening it.
> My last bike was a Dahon which I had for for five years.
> Not once did the headset need tightening.



As said earlier in this thread: It is quite normal on Bromptons that the headset needs retightening *once *after the running-in period. Though not perfect I'd consider this totally acceptable, the more as it is covered through the free first service for most people. For three years you did not bother to do that with the consequence that it is loose and you have to tighten constantly the improper way you are doing it (and probably even damage the headset longterm this way). Even if you would tighten it properly _now_ your issues will probably be gone. So clearly a user caused error and nothing to complain about or to blame the bike or it's maker.
It is like having experienced a puncture you'd pump up your tire two times a day for three years and complain about that instead of fixing that puncture once...

As for the Dahon: Most of those have a totally different construction on the headset. Different bike, different issues. I.e. the clamping mechanism on most Dahons needs sorrowful looking after and sometimes adjustment from time to time - with possibly harsh consequences if missed out in the worst case. No problem on a Brompton.


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## u_i (30 Jan 2019)

I left my new Dahon with a relative, for my use when I came around again. In the meantime he started riding it and soon he had to replace the chainring and to rebuild the rear wheel at a local shop. (Admittedly the chainring could have been bent in transport.) When I came around after a year I needed to give it to a dealer to have the headset and frame clamp replaced. The relative for sure does not abuse things, but can be negligent and certainly does not comprehend the issues of bike maintenance, as most bike users.


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## Kell (30 Jan 2019)

Me and Dahons really didn't get on.

I had two - one with the Clamp and one with the Lockjaw. Both were never right.Despite much tinkering and fettling.

And the wheels were the worst part of all.

On the one I bought new, both wheels needed tightening and trueing multiple times (each time at an LBS @berlinonaut ;-)) and the rear was done about 7 times and the front maybe 5. Each time it was a tenner to have done and would last around 6-8 weeks before needing doing again.

In the end I gave up and bought some Mavic Crossmax wheels with bladed spokes that couldn't come undone.

As for the Brompton and its headset. It did go back to the dealers for the check-up - why wouldn't you, it's free. So everything should have been tightened properly then. Unlike the assertions before which say that it happens mostly in the first few hundred k, mine wasn't a problem until much later in the bike's life.

I'd probably say midway through year two once I'd done around 5,000 miles. And I still think that the riding position may contribute to that. The fact that the seat's much further back means that a rider is pushing back on the saddle and pushing forwards on the bars. Thereby increasing the likelihood of ovalising both seat tube and head tube.

This is unique to small-wheeled bikes like the Brompton because of the extra leverage gained with long seatposts and stems.

It's not something I'd really thought about until now, but the weight distribution of a Brompton as set up from the factory is very different to how mine's set up. So not necessarily a design flaw, but the result of a modification.

User error in other words.


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## Ridesafe (7 Aug 2020)

Hi all
Just picked my brompton black e bike 2 days ago rode it for my 20 minutes head
Headstock loose took it back to the dealers they fixed it so with that today just been out 20 minutes same again im not a happy bunny ? Roger Leeds uk


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## berlinonaut (7 Aug 2020)

Sounds more like a not-so-competent dealer...


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## Gunk (8 Aug 2020)

Kell said:


> Mine is in constant need of a little tighten every few weeks.



You shouldn’t need to do that, you might have some grease on the threads which is causing that. If you clean them up and reassemble with a tiny drop of blue loctite it’ll stay in place. With this method I’ve never had a headset come loose.


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## berlinonaut (8 Aug 2020)

Gunk said:


> You shouldn’t need to do that, you might have some grease on the threads which is causing that. If you clean them up and reassemble with a tiny drop of blue loctite it’ll stay in place. With this method I’ve never had a headset come loose.


As said before: Using innovative tools like spanners instead of just fingers and this way properly securing the nuts agains each other is probably sufficient.


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## Gunk (8 Aug 2020)

berlinonaut said:


> As said before: Using innovative tools like spanners instead of just fingers and this way properly securing the nuts agains each other is probably sufficient.



It is a tricky job locking the two nuts together, it's really easy for the lower cupped nut to move and overtighten the headset, you need lots of patience to get it right. My method is to slightly undertighen it and let the lock nut turn the bottom nut very slightly.


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## berlinonaut (8 Aug 2020)

Gunk said:


> It is a tricky job locking the two nuts together, it's really easy for the lower cupped nut to move and overtighten the headset, you need lots of patience to get it right. My method is to slightly undertighen it and let the lock nut turn the bottom nut very slightly.


I don't get the problem.  Obviously you have to use two spanners to adjust and secure the headset properly as there are two nuts involved. Not especially tricky in my experience. If you only use one spanner you may end up with the situation you described. If you use no spanner you end up in Kell's situation.


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## Gunk (8 Aug 2020)

berlinonaut said:


> I don't get the problem.  Obviously you have to use two spanners to adjust and secure the headset properly as there are two nuts involved. Not especially tricky in my experience. If you only use one spanner you may end up with the situation you described. If you use no spanner you end up in Kell's situation.



Obviously you’re a headset guru 🙄


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## oldwheels (8 Aug 2020)

Yellow Saddle said:


> If it is that new and hadn't been ridden in the wet, the grease should be fine. No, don't worry about loose ball bearings. They have their advantages, and disadvantages.
> 
> Go for a ride and drink a beer.


I would be a bit wary about the grease being ok. I found on my Brompton that there was virtually no grease in the front hub after only a couple of hundred miles. I found this when investigating a mysterious noise from the wheel when in use tho' it spun freely and silently when lifted up. I have done the head bearings and there was still some grease there but not much.


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## rogerzilla (9 Aug 2020)

A headset that constantly loosens itself is often a sign that the head tube and fork need facing properly. Any decent bike shop can do it. It should be done at the factory but I suspect it isn't.


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## berlinonaut (9 Aug 2020)

rogerzilla said:


> I'm not sure Brompton do a good job of facing the head tube and fork crown at the factory, since this is the usual reason for a headset not being able to be adjusted properly. (...)
> 
> Add it to the list of Brompton design faults they still haven't fixed after 30 years...





rogerzilla said:


> A headset that constantly loosens itself is often a sign that the head tube and fork need facing properly. Any decent bike shop can do it. It should be done at the factory but I suspect it isn't.


You repeat yourself. Do you have any evidence for your claim or is it just your usual Brompton-hate? Judging from this thread:
- The OP had the issue once and has not reported back, so probably solved.
- Kell had the issue constantly for years. Caused by the fact that he "tightened" the headset with his fingers instead of using a spanner
- I reported that I know the issue from many new Bromptons that need retightening the headset once or twice over the first couple of 100kms - not a tragedy in my eyes.


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## rogerzilla (9 Aug 2020)

A headset that needs retightening after use is an improperly fitted headset. It isn't acceptable on any bike, let alone a £1000 one. Maybe it's necessary on a headset fitted with a lump hammer and a block of wood in the shed. I own a Brompton, have done for 11 years (I've had a couple more as resto projects along the way which I eventually sold on) so I'm not a Brompton-hater but nor am I an apologist or fan-boy.


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## Kell (10 Aug 2020)

Funnily enough - I did mine properly (once I remembered) and it's been fine ever since. 

It was certainly long enough ago for it to have completely slipped my mind that I'd even responded to this thread.


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## FolderBeholder (12 Aug 2020)

I started reading this thread as it was brought to my attention via the forum software‘s “alert” feature of activity, which brought me directly to It’s most recent posts. Then I realized I was the thread-starter! LOL

Today is Aug 11, 2020 and after the initial re-adjustment and tightening of the headset I originally posted about waaay back when....I’ve never had to give it a second thought (well, listen to a second complaint from the Missus about it is actually a more accurate description) and we ride our Bromptons quite regularly and still adore them. 

Hopefully that info will give “Ridesafe” hope for the same issue experiencing on their new Brompton.


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