Moulton SST -- reasons (not) to buy?

[speedsixdave]

Does anyone know what sort of tyres John Woodburn used for his record-breaking rides back in the day? If they were silk tubulars with a thin glued-on tread, that would have gone a long way to reducing the difference to larger-wheeled machines.

Tubs, but probably not silk. There were junior tubs around at the time that most early racing Moultons used - I have a pair still but they're not fit to ride, sadly. I suspect they were not as good as the finest Clement Setas of the day, but vastly better than any size of clincher tyres of the 60s.

I suspect clincher / wire-on technology has improved enormously in the last 50 years, and this has widened the gap between 700c and 349/369/406 wheels. Moulton's 369 Wolber tyres of the very early 1980s performed extremely well in (his own) tests against early 1980s clincher tyres. Similarly the 369 Wolber slicks of the late 1980s, developed with General Motors for their Sunracer solar-powered car, had very low rolling resistance, especially at very high pressures.

Now the fastest tyre in 406 is probably the Schwalbe Pro One. However physics dictates that, all other things being equal, this will have higher rolling resistance than the 700c Schwalbe Pro One. Not all other things are equal, though...

[speedsixdave]

Another interesting but ultimately fairly misleading experiment is The Cattle Grid Test. Go for a ride with a buddy with one of you on a big-wheel bike. Approach a cattle grid side by side at roughly the same speed, then both freewheel over the grid. See who has maintained their speed better on the other side!

This appears fairly instructive, but it doesn't really tell you much except that small wheels, suspended or not, don't roll happily in such extreme circumstances. Neither bike will perform well across a ploughed field, but again that does not tell you much about how your wheels will perform on a tarmac road, which is what is important with a road bike.

After 50 years there is sufficient real-world evidence to suggest that Moultons are not so intrinsically slow as to make Paris-Brest-Paris, the Race Across America or your favourite ride any less achievable than on a big-wheel bike. Nor is there compelling evidence from Moulton's occasional competitive successes (e.g. John Woodburn, Vic Nicholson and Reg Randall's RRA records and time-trial wins of the 1960s, Jim Glover's speed records of the 1980s) to demonstrate that the Moulton is faster in a straight fight than a big-wheeler.

It disappoints me somewhat that Moulton's work with practical fairings in the 1980s (and 1960s to a lesser extent) was not pursued further. A small-wheeler has the potential to carry a useful fairing, and the aerodynamic advantage of a partially-faired bicycle would make any debate over rolling resistance of small wheels moot.

[Mick F]

Thank you Dave, for those two very interesting and informative posts.

Cattle grids:
One of the first rides I did on mine, I rode up to our daughter's place in N Cornwall. I called in at a farm shop/cafe for lunch, and there's a cattle grid at the entrance gate.
I rolled over as I would have done on a "normal" bike.

I nearly fell off!
Moulton vibrated and shook violently and very nearly came to a sudden stop.

I've been over many many cattle grids since, but they get treated with a great deal of respect now.

[reohn2]

Speedsixdave
I have misgivings about fairings on bikes,this isn't borne out of experience but strongly suspect cross winds would play a big part in nullifying any advantage and could even affect handling safety adversely in cross head or tail winds at speed.

[Brucey]

certainly for four-wheelers (and I think also two wheelers) it is usually the best idea in a cross-wind if the centre of pressure is slightly behind both the midpoint of the wheelbase and/or the CoG. So 'normal' cars etc are usually OK and by contrast 'cab-forward' pickup trucks, flatbeds etc tend to be a bit of a handful in a really strong crosswind.

On two-wheelers the rider usually contributes greatly to the windage, but touring motorcycles that are rear-heavy with large front fairings can be pretty iffy. It is worth noting that the fastest motorcycle fairing is a so-called 'dustbin' one but these were banned from motorcycle racing because (between the weight and aero effects) they produced some highly unpredictable handling traits.


Carlo Ubbiali, riding a 250cc MV Agusta in ~1956 or 1957. Ubbiali won the 1956 lightweight TT and placed second to a team mate in 1957


Libero Liberati and Geoff Duke, practically banging fairings on identical Gilera 500s in the 1956 GP de nations


1957 Moto Guzzi 500cc race bike. This V8 powered machine could have been a phenomenal success. However it wasn't reliable enough early on; a year or two later the dustbin fairings were banned and in Italy moped sales had plummeted, which practically bankrupted Moto Guzzi; they couldn't afford to go racing with machines as expensive as this any more.

The moulton fairing upthread is unlikely to produce truly evil effects in a cross-wind because it is fairly shallow, side on. That it will have some effect is without doubt, but it may be no worse than (say) front panniers might produce on a conventional bike.

cheers

[reohn2]

.....The moulton fairing upthread is unlikely to produce truly evil effects in a cross-wind because it is fairly shallow, side on. That it will have some effect is without doubt, but it may be no worse than (say) front panniers might produce on a conventional bike.

cheers

Are you sure about that?
It's high up and 'flimsy' and would catch far more side wind than front panniers which are low down,small and heavy.
Thinks.... ...bicycles are much lighter than motorcycles especially on the front end

[Brucey]

most of it is below the handlebars; not that high after all. There is probably as much (or more) front windage on a bike with front panniers and a bar bag, which wouldn't be my choice but is commonly seen.

FWIW a tail fairing is probably a better idea (in combination with a small front fairing)



the above is interesting but the tail fairing looks a bit wide and the front fairing won't benefit greatly from being either pointy (*) or quite so elaborate.

(*) assuming that it isn't going to go supersonic....

cheers

[Mick F]

What are these "racing" Moultons like climbing in and out out of Millook in North Cornwall?

I managed the double chevrons in bottom gear - 34/28 and SA1st = 16.5" but it was a struggle.

Done it before on Mercian with (only) bottom 30/30 = 27" reasonably easily.

[pwa]

Another interesting but ultimately fairly misleading experiment is The Cattle Grid Test. Go for a ride with a buddy with one of you on a big-wheel bike. Approach a cattle grid side by side at roughly the same speed, then both freewheel over the grid. See who has maintained their speed better on the other side!

This appears fairly instructive, but it doesn't really tell you much except that small wheels, suspended or not, don't roll happily in such extreme circumstances. .

Off Topic, but we have a lot of cattle grids around here and they are best negotiated as fast as you can go. The faster you go, the less your wheels drop down into the troughs. In a car or on the bike. The only glitch in this approach is with cattle grids you don't know so well, because very occasionally you might find one that is in a poor state and needs a different approach.

[Mick F]

Staying off topic!

Cattle grids round here, are "directional" for the cattle and sheep etc.
T section at the external end, and I section at the inside end. 75% 25% perhaps.
This seems ,to me, to be more difficult for the animals to get over the I section section and easier for the cars and vehicles to get over the T section.

However, having crossed these thousands? of times, it's the T sections that create the bigger vibrations on a bike. The I sections seem smoother.
This is for both Moulton and Mercian. Mercian much easier though!

https://www.google.co.uk/maps/@50.50253 ... 312!8i6656

https://www.google.co.uk/maps/@50.50297 ... 312!8i6656

[reohn2]

Brucey
I'm still not convinced of the fairing's usefulness in everyday riding YVMV.

[Brucey]

faster for less effort? Keeps you warmer/drier in winter? On the downside the fairing will get damaged in a prang and may make some drumming noise. But if they were legal for racing every wiggo-wannabee would buy one in seconds flat; they make much more difference than any amount of 'special aero design' to the bike that lies within present UCI rules.

cheers

[reohn2]

faster for less effort? Keeps you warmer/drier in winter? On the downside the fairing will get damaged in a prang and may make some drumming noise. But if they were legal for racing every wiggo-wannabee would buy one in seconds flat; they make much more difference than any amount of 'special aero design' to the bike that lies within present UCI rules.

cheers

That being the case why doesn't every knowledgeable cyclist use one?
As I posted.....

[hercule]

I lose exactly the same amount of speed over cattle grids, regardless of small wheels or 700Cs.

I get off and walk!

I’m terrified of a front wheel being grabbed between the bars. Cattle grids round here are few and far between, more often than not they are on rarely trafficked roads and the bars can be rusted through or even missing. I adopt a circumspect attitude to them all.

[speedsixdave]

What are these "racing" Moultons like climbing in and out out of Millook in North Cornwall?

I managed the double chevrons in bottom gear - 34/28 and SA1st = 16.5" but it was a struggle.

Done it before on Mercian with (only) bottom 30/30 = 27" reasonably easily.

I agree that Moultons tend to be moderate climbers, and the steeper the climb (and thus the less smoothly one pedals), the more moderate they become. So what variables do we have?

(1) position. Assume riding position is the same on Moulton and Mercian.
(2) transmission efficiency. Assume this is similar on Moulton and Mercian, although the SA3 will introduce some additional losses.
(3) weight. Moulton is probably heavier than Mercian, which counts increasingly as the road gets steeper. Moultons can be lighter (under 10kg for the Speed) and could be lighter still if built with carbon monocoques. There is no fundamental reason why a suspended small wheeler need be heavier than a (suspended) big-wheeler.
(4) rolling resistance. As noted, 406 wheels will always have higher rolling resistance than 700c, with other wheel and tyre parameters being equal. This is a fixed constant and would be measurable, although it will be complicated by the varying suspensions of e.g. Moulton and Mercian.
(5) aerodynamics. Hard to isolate outside a wind tunnel but the steeper the hill, the less aerodynamics will matter.
(5) suspension losses. This is most difficult to measure as it will vary greatly depending on riding style and individual damping settings etc. There are also widely varying estimates of how much 'energy' is sapped by a bobbing suspension*. However it seems clear (to me) that moving suspension parts must absorb some energy which is not transmitted back into forward motion. And that's why I'd like to see some serious effort put into electronically-controlled suspension systems which could differentiate between inputs coming 'up' from the tarmac and 'down' from the rider. Sure, it might be expensive, but a top-of-the-range Moulton is £17000...

*Although bobbing front suspension while honking is very visible and appears to waste energy, the forces that cause it - the rider moving up and down above it - will be the same on a suspended Moulton or an apparently unsuspended big-wheeler if ridden in the same fashion. So those up-and-down forces (sorry for the terminology) must be transmitted through the fork and tyre of e.g. Mercian in the same directions, so into flexing and compressing the steel fork to a small degree and into compressing and flexing the front tyre to a larger degree. As tyres grow larger and are run at lower pressures, the more the tyre will deflect when honking. You can argue the relative efficiencies and hysteresis of steel fork vs Moulton damped or undamped steel spring vs pneumatic tyre (and feel free to do so) but wherever those 'up-and-down forces' are going, they're surely not going into driving the rear wheel round.