50PlusCycling

I’ve had a Moulton and a Brompton, and have done a lot of riding on both.

My Moulton is an APB with a Reynolds 531 frame and fork. As originally equipped, it was a rather heavy 8 speed bike with a grip shifter, V brakes, and a steel square taper bottom bracket. It was not a lightweight, but it was a beautiful bike with a great ride. After replacing pretty much every part on the bike, and swapping the old 8 speed for a newer 22 speed Dura Ace Di2 driveline and lighter wheels, the bike is no longer heavy. The front fork is adjustable for preload and damping, and, when properly adjusted, I don’t have an issue with it “robbing power” when I am riding. There are no words to describe how wonderfully smooth and steady this bike is, add a 531 steel frame to a well-engineered suspension system, and the latest in component technology, and you end up with a great ride, almost heaven on wheels.

My Brompton is an S3L, with a Sturmey Archer 3 speed driveline. The weight is about the same as the Moulton before it went on a diet. The Brompton is a nimble commuter, and was a wonderful bike when I was commuting around the city for work. I rode it to the station, carried it on the train, the from the station to my office, and parked it folded up next to my desk. I love the style, utility, and form-follows-function engineering. The issues I have with the Brompton are the old-school shifting, which is not particularly smooth or quick, and the limited gearing, which, while fine on the flats and gentle hills, is not adequate for the mountainous areas around the city, or some of the steeper hills in the city itself.

I see these two bikes as engineered for different purposes. The Brompton is a townie bike, which is easily folded, transported, and stored, a superb urban tool. The Moulton is a little harder for words to describe, it is a beautifully-made machine which is pulls at the heart strings of someone who loves riding bikes.

Jipe

My comparison is based on an upgraded Moulton Speed that weight about 8.3kg and an upgraded Brompton Superlight with a Rohloff transmission that weight about 11kg (its fully equipped with mudguards, rear rack, dynamo hub lighting for an all year/every day use).
Both bikes have now the same type of tires, i.e. Continental Contact Urban 32x406 and 35x349.

davidhunternyc

The thing is, sure, you can customize the Moulton but you can customize the Brompton too. Full 12 speed carbon crankset, carbon wheels. You can do anything until your heart's content. This guy on YouTube, Shu, from "Brompton Family Time" customized his Brompton T-Line to under 15 pounds, 6.8 kg. Then there's Kinetics in Glasgow and many customizers in Asia. It seems to me that for every argument for a Moulton, there's an equally strong argument for Brompton and I don't think that a fully carbonized Brompton will be slower or less comfortable than a Moulton.

Which one do you ride more and why? Customizing can go on forever. For instance, I recently discovered the Hubsmith Bumble P CA349 wheels for Brompton. Stunning.

Jipe

Those two bikes are very different for different use !

The Brompton is a utility bike used for shopping, commuting... when I need a very small folded bike. When a slightly bigger folded size is OK, I prefer my Birdy.

The Moulton is a leisure bike only. I do not use it for something else, the price of the bike makes, that even if it is insured against theft, I do not dare to leave it alone anywhere and its not possible to carry it easily like my Brompton and Birdy since its not folding (with the special wheels, eebrakes calipers, AX-lightness saddle and titanium axle pedals, it costed me more than 12K€ end of 2017, no idea how much it would cost now).

Duragrouch

"Where the Mouton does shine is on gravel."

That is just tire size, not overall design. The Moulton has 20" (406 or 451?) tires, no? 20"/406 has many more options in terms of wider than 451. Bromptons use 16"/349, which has a disadvantage on softer surface simply due to the diameter (worse "cone index", sinks in easier, less "flotation"), and I think also less available in wider sizes.

If you want the soil performance of 20"/406, there are plenty of folders with better folds than the Moulton, though still not nearly as compact as the Brompton, until you get into a Helix with 24" tires but extremely compact fold.

When they design automobiles, you know what the first thing they decide is? Tires. Everything, from the suspension and steering geometry, to brakes, to packaging (space), is all designed around the chosen tires, in both size and stiffness, especially dynamic. Same with bicycles, and motorcycles, and every other wheeled vehicle.

Jipe

No, the performance of the Moulton on gravel doesn't come from its wheel size (most Moulton have caliper brakes that do not accept tires above 32-35mm) but from its frame geometry and suspension. For the same reason + 50mm wide tires, the Birdy also perform well on gravel.

But the Birdy is a folding bike, the Mouton is not folding at all, just separable in two big pieces and dismountable for some models).

tcs

Interesting, given the Moulton TSR (and some other models) have a unified rear triangle and the bottom bracket is rigid to the rear wheel.

The Brompton, however, has a low pivot and every pedal stroke compresses the suspension.

This was all worked out by mountain bike designers in the years between the design of the Brompton and the design of the Moulton APB (forerunner to the TSR).

Schwinnsta

I think you misunderstand. Look at the frame, it swings, every pedal stroke does compress the suspension, though the losses are worse from the front suspension that the rear. The bottom bracket is not rigid to the rear wheel.

Duragrouch

I do agree with the above, that bikes with rear suspension, not properly designed, do suck pedaling energy, as well as make the bike bob up and down. A proper suspension design to counteract this, takes into account, both the chain tension, and also the ground thrust at the rear tire contact patch.

That said, interestingly, I read an article in Bicycle Quarterly (think Architectural Digest, but for bikes, very high-end stuff featured), and the publisher and writer (and from what I can see, serious, hardcore rider) stated that his experience has been that the rear triangle (on a rigid frame) is best when it has a small amount of vertical flex, that suits the rider's pedal force and riding style. He did not have quantifiable numbers, just expressed it in qualitative terms. However I've read enough articles in the magazine that were carefully researched and quantified, that I give some credence to the writer. (Among others, comparing rolling resistance of skinny versus wider tires (dispelling some assumptions), and pannier aerodynamics, the latter of which helped explain the trend toward only front panniers and handlebar bag, instead of rear panniers.) I could imagine a frame where a small-displacement flex/spring frequency might line up with the rider's pedaling stroke, if there was not much energy loss (damping) in the frame (not true with a rubber suspension, for example). I've wondered if it's at all analogeous to sport racquet design, where for some, a lower tension can actually increase power, by prolonging the ball contact time. I don't play cricket, but have read that they treat the (willow?) bats with raw linseed oil, not as a protective coating, but to sink in and increase the "springiness" of the bat, for, I am guessing, the same reason.

As far as Bicycle Quarterly, it's expensive, I am lucky enough that my local library has a subscription. The articles are very well written, and they do cover modern designs, but it's clear they have a soft-spot for serious retro-grouch classic and vintage. The publisher also seems to own a (French/formerly-French?) maker of said parts, prominently advertised. One such part is a new design with a pull-cable in both directions (down-tube shifter only), to eliminate the return spring of the rear derailleur, for feather-light shifting force. I wish they had same for a front derailleur, as the spring on mine is way too strong, makes it impossible to use a left grip-shift, but it's the only derailleur that fits the adapter to allow mounting one on my folding frame.

Jipe

No, on the all current Moulton with 20" wheels (Jubilee, Speed, XTB, SST, TSR; New Series but not AM with 17" wheels) the bottom bracket is part of the suspended rear triangle, pedal strokes do not compress the suspension.

Schwinnsta

Nevertheless, each pedal stroke does compress the suspension since the suspension is full time, it's just not as bad as the front suspension. Such is the problem of suspension. pinholecam is correct in saying suspension is a double-edged sword.

Jipe

No, as said, for all Moulton with 20" wheels, the pedalstroke doesn't compress the suspension because the bottom bracket is part of the rear triangle the chain traction when pedaling doesn't interact at all with the suspension, look at the picture below.

The axle of the rear triangle is just above the bottom bracket (the big bold just above the bottom bracket).

Schwinnsta

Nothing is different, but they have moved the pivot point above the bottom bracket. It is still free swing.

Jipe

The bottom bracket is integrated into the rear triangle, there is a rigid connection between the bottom bracket and the rear wheel axle with a fixed distance like on a bike without rear suspension, the traction on the chain due to the pedaling doesn't compress the suspension like for instance on the Brompton, the Birdy and most MTB (even those with a very sophisticated rear suspension).

tcs

Uh, it's all one piece of brazed steel in a triangular structure.

Schwinnsta

[QUOTE=tcs;23126523]Uh, it's all one piece of brazed steel in a triangular structure.
/QUOTE]

Yes, the whole triangle pivots. Does it not? If you took out the suspension block and made it solid so it could not rotate, then I would agree with you. For our intents and purposes, the whole bike can be a black box. If it has suspension front and rear, and I put a force on the pedal, it is going to bob with each application of the force.

Jipe

No, if you put force only on the pedal like when pedaling sitting on the saddle, it won't bob.

It will only bob if you move your whole body mass like when pedaling standing, it will bob, but the pedaling force won't compress the rear suspension and there won't be a loss of pedaling energy like when its the pedaling that compress the suspension.

Schwinnsta

Color me skeptical. Here is a picture of my APB




This one bobbed.

Below is my first one. It bobbed too. I thought the APB would ride much better, but it did not. Interesting because the standard had 349 wheels.

Jipe

I see only one picture of a yellow Moulton.

Its rear triangle is a totally different concept than my Speed and all other current Mouton with 20" wheels, the rear triangle of this yellow Moulton its the same concept as the one of the current AM models with ETRTO369/17" wheels were the bottom bracket is part of the main frame with as consequence that the traction of the chain when pedaling compress the rear suspension.

What makes the difference between this yellow and my Speed is not the fact that the rear triangle pivot is behind the BB on the yellow and above the BB on the Speed but that on the Speed, the BB is part of the rear triangle, not part of the main frame like on the yellow.

50PlusCycling

[QUOTE=Schwinnsta;23126557]The center of the pivot is the bottom bracket, just like in a hard tail bicycle. In other bikes the center of the pivot would be the point where the hinge connects the swing arm to the frame. In this thread we are comparing Moulton to Brompton, and the rear suspension in the Moulton is superior to the Brompton. Any kind of suspension will absorb power, but some designs absorb less than others.

Schwinnsta

[QUOTE=50PlusCycling;23127788]I got as much from Jipe. The Moultons I have seen had basically the same system as the Brompton. I have not ridden the new system, but I suspect that they use energy, though perhaps less.

50PlusCycling

You can’t simply get on one of these bikes and make a judgment without adjusting it first. If you look at the front suspension, under the rubber dust boot on the front there is a ring which you use to set the suspension spring compression. If you are a heavier or lighter rider, you adjust it to compensate for your weight and how firm you want to suspension to be. On the bottom of the fork are the plates between the fork and the arm which pushes upward against the spring. The 6 nuts on this plate can be tightened or loosened to adjust the suspension damping. Properly adjusted, the suspension is firm while riding, but gives way when the front wheel hits a bump.

It took me quite a lot of trial and error until I got the suspension properly set up. But once I found the sweet spot, it’s been wonderful.

The standard rear suspension is not adjustable, but it is more of a shock absorbing system than an actual rear suspension. Overall, the system is well designed, and works very well.

Schwinnsta

[QUOTE=50PlusCycling;23127788]And what makes you assume that I did not do that? I went all through that. I tried all the adjustments. I wanted to like this bike. For some really bombed out roads, the suspension actually helped, and it was faster on these roads. However, as bad as the roads are here, the suspension energy losses just did not make sense. It was not worth it. For me and on my streets, I concluded suspension was not worth the weight and complications. My Swift with its 2-inch tires rides faster and more efficiently than the Moulton did.

edwong3

I think the Moulton caters to those who like the strange, unusual or unique. I imagine it can be quite the conversation starter wherever the rider goes. There are products like that in every category. Sometimes someone will buy a product like the Moulton "just because".

The Brompton is versatile, sort of like the "Swiss (or rather English) Army Knife" of the folding bicycle segment. So, it makes sense, I guess.

Ride what you like.
Edward

Jipe

The Moulton made by Moulton at the Moulton factory are race bikes with small diameter wheels (originally and still for a part of the models 17"/ETRTO369, later 20"/ETRTO406), they are not folding bikes.

This is not the case for the TSR and SST which are more utility bikes but also not folding.