Tag: speed

Aerodynamic research using the Moulton small-wheeled bicycle

The IMechE Journal of Energy and Power, Volume 20 No 3, 2006 featured an article on Aerodynamic research using the Moulton small-wheeled bicycle.

The abstract reads as follows: "This short article describes aerodynamic research carried out using the Moulton small-wheeled bicycle. Alex Moulton's initial research, applying streamlined cowlings to his early small-wheeled bicycles, is briefly described. His later collaboration with Douglas Milliken is covered in greater detail. Milliken's many experiments with fairings included wind tunnel tests in crosswinds, an aspect of bicycle science rarely investigated hitherto. An important finding was the ability for a streamlined bicycle under certain conditions to sail. The Moulton–Milliken collaboration led to the development of fully streamlined bicycles, using the conventional riding position, which twice broke a speed record."

The record mentioned is of course the world unpaced cycling record over 200m (conventional riding position) in 1985. The speed attained was 50.21mph (80.79kph), the bicycle was an Alex Moulton AM.

Jim Glover, broke the record again in 1986, on a new improved Moulton Liner. The new record, 51.29mph (82.53kph), still stands.

Moulton record breaking Liner

More details on the bike and the record can be found on Doug Millken's site, and pictures can be seen in Tony Hadland's pictures from the Moulton Museum.

Duomatic on my mark III

I used one of my Mark 3s as a fixed gear commuting bike for almost a year, and while I loved riding fixed, and I loved the simplicity and the low maintenance aspects, I found it did have it's limitations.

Firstly, while I love the simplicity, one gear was just not enough. I had no problem honking up the occasional hill, but my commute at the time was through Dublin's Phoenix Park, which has a lovely 4km stretch with a 1% decline and a prevailing tailwind, that always calls for a higher gear than an all purpose gear.

Secondly, I was worried about my knees. Most fixers will tell you it has no effect on the knees, but I rode while recovering from a knee injury (unrelated to cycling) and I can tell you that even the very subtle pedalling to slow down technique places a considerable strain on the knee.

And most importantly, while I made sure the chainline was perfect, and the chain tension was always ok, I was always worried that it would dump the chain, or catch a shoelace, trouser leg or finger with horrible consequences. Sure, the risk was low, but the consequences were potentially so bad for man and machine, that I found myself unwilling to take even that small risk anymore.

Still wanting a simple, low maintenance setup, I picked up a new old stock Sachs Torpedo Duomatic hub on eBay, built it into a 16inch wheel, and tried it out last night on the same Moulton Mark III.

It's a 2 speed hub, with coaster (back pedal) brake. The "low" gear is direct drive, and the high gear is a 36% overdrive. Gear change is effected by rotating the cranks backwards a few degrees, but not quite as far as required to engage the brake.

It's a really simple setup... there are no gear cables to worry about. And unlike most hub gears, there are no adjustments necessary. It just works. It's got the simplicity of a fixed gear / singlespeed, but with an extra gear for those slight downhills or tailwinds, especially in a mostly flat city like Dublin.
When I rode fixed, I used 56x13, giving around 70 inches on the Moulton. With the Duomatic I'm using 56x16 giving gears of 58 inches and 78 inches. I think that I'll play around with these ratios though.

I'm using a 3/32 inch chain, just because that's the size the chainring and sprockets are. The only problem is that the 56x16 requires the use of a half link. Half links in 3/32 size are hard to find, but I did manage to find some in St John St Cycles.

They're not a very good match for a Sram PC951 chain though. I think they're designed for a chain with taller links. They're also very slightly wider than the PC951 making use of a master link with the half link impossible. The easiest solution is probably to replace the 16t sprocket with a 17t.

Alternatively, I suppose I could just change to a 1/8 chain, with the existing chainring and sprockets... as far as I know the only downside is extra noise.

The test ride was quite nice. I intended doing a 10 minute ride, but it turned into a 30 minute ride.

It takes a little practice to change gears without engaging the brake. The brake is good for a rear brake... obviously useless in an emergency, but perfect for slow easy stops. I used it a lot more than I would normally use a rear brake (i.e. I used it). So it should prolong the life of my front rim, as well as the back rim.

Engaging the brake, also changes the gear, which is great when braking in high gear, as it is quite likely that the low gear will be required next. However, if you brake in low gear, the high gear gets engaged, most likely requiring another backpedal to engage the low gear again before pedalling away. It's only a minor inconvenience, especially when it's actually quite easy to audibly determine what gear is engaged.

How? When the hub is in overdrive, it ticks, whereas direct drive is more silent. The ticking is perceptible as soon as you begin to rotate the cranks and before any effort is engaged, so you know you're in overdrive, even before you try to drive the pedals.

If this hub was to come on the market now, I'm sure the reviews would ridicule it as primitive. But that's it's beauty, it's simple, it works, it's not black. And it requires a little bit of skill and finesse to use it most effectively.

When the fixed gear craze goes out of fashion, as it inevitably will, and cyclists search for something that is simple AND functional... these will be in high demand. Apparently Sturmey Archer are considering remaking the ASC hub, the 3 speed fixed gear hub. Any chance that SRAM would remake the Duomatic??

Information on the Duomatic can be found here

Anniversary of Tom Simpson's death

Forty years ago today Tom Simpson died on Mont Ventoux, while competing in the Tour De France. Aged 29, he had been an Olympic silver medalist, World Champion, and the first British rider to wear the yellow jersey in the Tour De France.

On the cover of Tony Hadland's excellent book The Moulton Bicycle, Simpson is photographed test riding a Moulton Speed at Herne Hill.

On an external wall of the Hall, Alex Moulton's home in Bradford on Avon, there is a memorial plaque depicting the same scene.

Today, the spot where Mr Tom died on Mont Ventoux is marked by a memorial, where cyclists still leave water bottles, hats, inner tubes or whatever they have spare, as a mark of respect to the legend. The British cyclist David Millar threw his hat to the monument while competing in the Tour a few years back, showing whose wheels he was following.

Does anyone have any further details on Simpson's Moulton connections? If so I'd love to hear them.

Some very special Moultons

When I ride my 1964 Moulton Deluxe or my Mark 3s from 1970 and 1973, I can sense the stares from people who have never seen such bikes before. It makes me feel like I'm riding something quite rare.

But in reality, over 100,000 Moulton deluxes were made and over 3,000 Moulton Mk 3's. They are not that difficult to find. However, over the years, many very special Moultons have been made. While the BMC factory in Kirkby and later the Raleigh factory in Nottingham were churning out Moultons, the factory in Bradford On Avon was often producing limited edition or one off specials.

Below are a few examples from Ken Butterfields photos...

This Moulton S Safari had been overpainted black. The black paint was removed using Nitromors, exposing the original chrome finish.

This Mark 3 was built by Jack Lauterwasser for his own use. It features a unique 10 speed drivetrain with 3 levers. The Sturmey Archer hub (I presume originally a 4 speed) was converted to 5 speed, with 2 rear sprockets and a custom derailleur. It's got lots of special features - 531 forks with Campagnolo ends, narrow bottom bracket, Mafac cantilever brakes

Another black Mark 3 this time, but very different. This one has derailleur gearing, and a prototype rear triangle with pump mounts.

Ken has lots more photos which are worth checking out, such as this gorgeous Speedsix

The original Moulton Bicycle

Twenty years before the first spaceframe Moulton bicycle, the original F-frame Moulton bicycle was launched. Alex Moulton, an engineer with experience in the automotive industry, and a recreational cyclist, decided to go back to first principles and question every aspect of the design of bicycles.

Questions such as :
Why had the design of the bicycle not changed in any fundamental sense since the "safety bicycle" was developed, replacing the Penny Farthing in the 1880s.
Why, when the wheel sizes of most road going vehicles had reduced with the improvement in road surfaces, had the bicycle wheel remained so large?

After 5 years of development, the original Moulton Bicycle was launched and it was a revolutionary design. The concept consisted of a number of key principles :

  • Small wheels were found to be stronger and lighter than large wheels. They produced less wind resistance, could be more easily accelarated.
  • Small wheels provided no more rolling resistance than large wheels, provided that high pressure tyres (which in 1962 meant 60 psi) were used. The optimum wheel size was found to be 16-17 inches.
  • Small wheels provided a more bumpy ride on paved roads, so the use of suspension was essential.

Additionally, the following features are common to the Moulton bicycle range:

  • The low stepover height compared to the standard bicycle was safer for men, and more convenient for women. It was also safer in the event of a crash insofar as the rider was not "trapped" with one leg either side of the top tube.
  • The ability to carry luggage low down on the centre line of the bicycle, providing more stability.
  • The separable frame, which does not compromise stiffness or stability compared with the non-separable frame, and featured in the f-frame Stowaway model (and in most of the spaceframe models) allows for easy transportation and storage.

    The new bicycle was a revolutionary design, and for a while Moulton was the largest bicycle manufacturer in Britain. The following video dates from the time of the launch of the Moulton bicycle.

    These principles are the core of the Moulton concept, and have remained so through to the very latest spaceframe models.

    The Moulton Range

    The Basic Range

    Continental – the cheapest Moulton with a single speed hub and back pedal brake.
    Automatic – replaced the Continental, had a two speed hub and back pedal brake.
    Standard – the basic model, 4 speed hub.


    Deluxe – a higher spec model, 4 speed hub
    Speed – similar to a standard but with a sportier riding position, 4 speed hub
    Stowaway – the first separable moulton, 2 speed hub with back pedal brake.
    Safari – a fully equipped model for touring. 4 speed hub with optional 2 speed derailleur.
    Speedsix – a racing model with 6 speed derailleur gears.

    The Standard and Deluxe are the most common models by far, and are quite inexpensive to buy. The other models vary in terms of rarity, desirability, and price.

    The S Range

    The S range is very rare, and very collectable. Each model is a higher spec version of the original Deluxe, Safari and Stowaway with slightly larger 17inch wheels, lighter components, and optional chrome finish.

    The picture below is a Moulton S Safari in chrome finish, from Ken Butterfield's photos on Flickr

    Only around 10 S Speeds were produced and the location of most of them is known. However, it looks like there may be a few still unaccounted for. Most F-frame collectors dream of finding an S Speed in a skip or a garage somewhere!

    After the Raleigh takeover the following models were produced:
    Moulton Major – an updated Standard
    Moulton Major Deluxe – an updated Deluxe

    The Mark 3 / Mark III / Mk 3
    This was a new departure in design, with the most recognisable feature being the rear triangle and squashball suspension. This model has a shorter wheelbase than the older Series 1 and 2 models and was fitted with a 3 speed hub with drum brake.

    • There were also a number of other models produced - smaller wheel versions for children/teenagers, export models, and models made abroad under licence. These will be the subject of a post on another day!