Bounce

[P Walsh]

About 15 years ago my employer bought a 7 speed Brompton for use by the staff. When it arrived everybody wanted a go, but most were not regular cyclists and were put off by the twitchy steering. So I finished up as the only one who was interested in using it. To ride on the flat it was fine, but when climbing I found that the flex in the frame made progress difficult. With my 14 stone of mass combined with the pushing down of the pedals on a 1 in 10 hill a springy bounce action developed. For climbing it was an appalling bike. A bike for lighter people, perhaps, or for people who don't ride up steep hills.

Are Bromptons still like that? I haven't ridden one for more than a decade and they may have changed.

[mrcharly-YHT]

You can get a firmer shock stopper - that will help.

Ride in lower gears, pedal smoothly and don't expect a lot from a folding bike.

[Tewdric]

I have the firm block on my new one.  It's not as firm as the firm block in my last one but still firm enough to prevent obvious bouncing.  I also have -18% gearing on mine which makes it about right if you ever have to ride uphill!  There is a bit of flex in ten frame as you'd expect but nothing of any concern, to me at least.

[Kim]

Firm block, S-type and properly low gearing (Bromptons suffer from being designed for pootling around London) all make a difference on hills, though it's still got the twitchy steering and bendy frame, and you can end up fighting the suspension at some cadences.

The twitchiness of small-wheeled bikes is always a bit alarming when you first ride one.  I found the flat-barred Brompton felt a bit less wobbly in that respect, though accept that non-regular-cyclists may find the riding position off-putting.  I think it's just something you have to get used to, which is fine unless you find it too scary to put in the couple of hours of riding it takes to get the hang of it.  The other side of this is that once you do get used to it, the twitchy steering is great for nipping about in traffic.

The main issue I have is that the Brompton is substantially harder work than other bikes.  Fine for nipping around town (which is after all what they're designed for), not so much for longer rides.

[P Walsh]

I got the impression they were built for people lighter than me. The bending of the frame was startling and made me realise how early bike designers had arrived at the Diamond Frame. Even the handlebars flexed more than I was happy with. I was worried that it might break through fatigue. The twitchiness I enjoyed, along with the ease of acceleration with tiny wheels.

[Kim]

I suspect that rider height is more relevant to frame stress than weight.  But IME frame flex is something you only notice for the first five minutes when you ride a new bike, or when something's intermittently rubbing.

TBH, with a frame shaped like that it's going to be bendy.  That's presumably why they use steel, so it doesn't fatigue.  I work on the principle that bigger, stronger people than me go touring on them with serious luggage and don't seem to break frames (or even seatposts) with any regularity, so it's probably going to be fine.  The usual weak point seems to be the quality of the wheel build.

[Zipperhead]

I'm about 6' 4" and weigh about 100kg and apart from the bars flexing I can't say that I notice the frame flexing.
Certainly though the firm block makes a difference. The quick steering is definitely an asset in traffic, I think the only time I've found it disturbing is when I've just got off the tandem and hopped onto the Brompton.

The only problem that I've had with the frame was due to a manufacturing defect, and despite it being 10 years old at that time Brompton replaced the frame for free.

My newer one did seem to have better built wheels than the old one, but after racking up a few thousand miles on it through autumn & winter I retensioned the back wheel at the weekend.

Pretty much everything in life involves compromises, a folding bike is just a different set of compromises to a regular bike. In return it does some things a bit better/more easily.

[rogerzilla]

I have the firm block with a jubilee clip round it too.  It is just about OK.  The block is really there to give a resilient interface between the rear triangle and the main frame (which are only kept together by the rider's weight*) rather than for any real suspension purpose.  If the block were a very hard substance, like Delrin or something, I suspect it would rattle on bumps as the rear triangle lost contact with the main frame.

*the optional clip is really just for people unnerved by what happens if you try to carry an unfolded Brompton

[Kim]

I have the firm block with a jubilee clip round it too.

Did the blocks get redesigned at some point?  Mine is ribbed and conical (ooer), so doesn't look particularly conducive to a jubilee clip staying put around it.

*the optional clip is really just for people unnerved by what happens if you try to carry an unfolded Brompton

I'm sure someone must have had a speedbumps incident on one at some point...

It's now a standard feature.  You can quickly enable and disable the clip function by rotating the suspension block, to suit the multi-modal:cyclocross ratio of your journey.

[Zipperhead]

I have the firm block with a jubilee clip round it too.

Did the blocks get redesigned at some point?  Mine is ribbed and conical (ooer), so doesn't look particularly conducive to a jubilee clip staying put around it.

Yes they did. They used to be a constant cylindrical section, and I think originally only in one firmness rating. Then they became ribbed.

[Riggers]

Get out!

[Zipperhead]

Ribbed for pleasure sir

[quixoticgeek]

For several years I used the older suspension block, along with the jubilee clip fix - aka stick a jubilee clip round the suspension block,  it firms it up rather nicely.

I have since replaced this with a firm suspension block. It's got some bounce on it if I trigger it, but beyond that, it doesn't wallow the way my old un modified setup did.

HTH

J