Tech advice...Brompton M6L

[Kell]

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.

 

[berlinonaut]

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...

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.

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.

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...

 

[Kell]

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.

 

[berlinonaut]

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.

 

[u_i]

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.

 

[Kell]

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.

 

[Ridesafe]

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

 

[berlinonaut]

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

 

[Gunk]

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.

 

[berlinonaut]

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.

 

[Gunk]

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.

 

[berlinonaut]

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.

 

[Gunk]

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 🙄

 

[oldwheels]

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.

 

[rogerzilla]

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.