Moulton SST -- reasons (not) to buy?

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dezzie
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Re: Moulton SST -- reasons (not) to buy?

Postby dezzie » 6 Mar 2019, 8:48pm

I have seen the sst next to a tsr in the shop in York last summer, loved the Sst it just looked nicer, i wanted one ever since with the igh hub but still have 2 f frames to finish, a nice folder there that could really be made into a weapon, xootr swift, the new xtb is 3.5k and the flyte expected to be around 3k, options of flat or drop bars, possible seperable version might come out in the future!
Regarding front disks, anyone tried a pacific reach? Its more what i would expect the Moulton to evolve into as it has polymer suspension with short travel and disk brakes all round for less than sst money.

igauk
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Re: Moulton SST -- reasons (not) to buy?

Postby igauk » 7 Mar 2019, 12:41am

I don't have a great deal to add to the comments posted already but FWIW I've been riding a second hand (but very little used) TSR 30 for the past 12 months. This replaced a traditional Reynolds 653 tubed, 700cc wheeled, Aravis Audax. Moulton is Campag Centaur/Chorus 10 speed triple, Aravis was Shimano Ultegra 10 speed triple. Aravis had a Shimano dyno hub, Moulton has an SP. I've also upgraded to the progressive wound 'race' spring at the front, as much to even out the front and rear suspension feel as anything else, and put on my own stem, saddle and fitted mudguards. Although very different beasts spec for spec they're pretty much identical.

I think the suspension losses are greatly exaggerated. Although most of the scientific research has been conducted on mountain bikes (rear and full suspension, with various geometries) losses seam to be in the range of 2-6 watts, the higher figure when climbing out of the saddle. The journal 'Vehicle System Dynamics' has quite a few articles on the subject. This is far less than the extra energy required to pedal a non-suspended bike over a rough surface at the same speed, and the gap between mountain bike trails and our road surfaces seem to be narrowing by the day. What I don't think is taken into account as often is the higher rolling resistance of the smaller wheels. Given the limited tyre choice available I think this is literally more of drag than anything else (although above about 40kmh you also notice the aero drag).

Is the Moulton slower overall? Possibly/probably, but this depends on the terrain and I don't have the data to form a reliable conclusion. Is it more comfortable than the Aravis, undoubtedly. Is it more comfortable than a say a Trek Domane with its Isospeed decoupler or a wide tyred gravel bike? Who knows! But I do appreciate it's swift acceleration, combination of sharp handling and stability, distinctive looks and ingenuity. For comfortable, fast, long distance riding there might be a better compromise out there but for the time being I'm pretty happy with it (and I got to buy myself a lovely Wanner grease gun).
Moulton TSR 30

Samuel D
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Re: Moulton SST -- reasons (not) to buy?

Postby Samuel D » 7 Mar 2019, 8:19am

I agree that rolling resistance has to be the main source of any slowness of a Moulton. 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.

pwa
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Re: Moulton SST -- reasons (not) to buy?

Postby pwa » 7 Mar 2019, 8:38am

If someone could be bothered and had the resources it would be interesting to compare how small suspended wheels ride over different surface types compared to unsuspended 700c wheels with as close to the same tyre profile and composition as possible. My nagging suspicion is that small wheels drop down further into low points in an uneven road that larger wheels would bridge, and that the front lower edge of the smaller wheel presents a closer-to-vertical attack face to small obstacles like road chippings.

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Mick F
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Re: Moulton SST -- reasons (not) to buy?

Postby Mick F » 7 Mar 2019, 8:50am

Tyre size for tyre size, the smaller the wheel, the less the footprint.
Rolling resistance is therefore less ............... not counting road surface of course.

Roll-out tests by me Mercian vs Moulton, Mercian wins hands down. This over YEARS of testing on the same slope.
I have said before, that a larger wheeled machine accelerates faster than a smaller wheeled machine when freewheeling from rest (no pedalling and no push off). I don't know why, but it's true as I'm sitting here.
Mick F. Cornwall

pwa
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Re: Moulton SST -- reasons (not) to buy?

Postby pwa » 7 Mar 2019, 8:56am

Over the years I have had to use sack trucks. The ones with larger wheels roll easier than those with smaller wheels on anything other than the smoothest surface. Moulton try to overcome that disadvantage with suspension. But suspension is a tricky thing to get right. Having a bigger wheel is a simpler solution.

Brucey
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Re: Moulton SST -- reasons (not) to buy?

Postby Brucey » 7 Mar 2019, 9:01am

Mick F wrote:Tyre size for tyre size, the smaller the wheel, the less the footprint.
Rolling resistance is therefore less ................
.


'not necessarily' to both.

cheers
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reohn2
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Re: Moulton SST -- reasons (not) to buy?

Postby reohn2 » 7 Mar 2019, 9:17am

pwa wrote:.......... My nagging suspicion is that small wheels drop down further into low points in an uneven road that larger wheels would bridge, and that the front lower edge of the smaller wheel presents a closer-to-vertical attack face to small obstacles like road chippings.

That's where the Moulton's suspension should play it's part in evening out the poor small wheel ride quality.I have a Tern folder(I'm not comparing it with a Moulton)which on a smooth road rides OK but on anything less than smooth and the rid becomes harsh,the bike came with 32mm Kojaks which gave a very harsh ride and were swapped for 2in Big Apples
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reohn2
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Re: Moulton SST -- reasons (not) to buy?

Postby reohn2 » 7 Mar 2019, 9:28am

pwa wrote:Over the years I have had to use sack trucks. The ones with larger wheels roll easier than those with smaller wheels on anything other than the smoothest surface. Moulton try to overcome that disadvantage with suspension. But suspension is a tricky thing to get right. Having a bigger wheel is a simpler solution.

I agree and there's far more choice of tyre to choose from.
But even then tyres and tyre pressures play a large part.
Mike Burrows did some roll down tests with a variety of tyres,on small 406 wheels IIRC,Marathon Plus came out tops.
I've ridden M+ tyres on 700C wheels and they are a horrid ride which I couldn't abide for anything but a short trip to the shops,they're also very heavy and so sap energy so wouldn't be my tyre of choice.
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Samuel D
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Re: Moulton SST -- reasons (not) to buy?

Postby Samuel D » 7 Mar 2019, 9:43am

Mick F wrote:I have said before, that a larger wheeled machine accelerates faster than a smaller wheeled machine when freewheeling from rest (no pedalling and no push off). I don't know why, but it's true as I'm sitting here.

I believe it’s because the rolling resistance of the small wheels is higher. When freewheeling at near-zero speeds, rolling resistance is practically the only thing checking your motion. This is as plain a proof as you’re going to get that the Moulton’s tyres are draggier, in large part because they’re smaller.

A couple of anecdotes:

Last year a friend sold me a pair of used Specialized Turbo Cotton tyres that I recently put on with the arrival of good weather. Their ease of rolling is hard to believe, and the difference is most obvious at low speed as theory predicts. I have to push my bicycle down a corridor and through a couple of doors to get it outside. Apparently my arm was finely calibrated to the force needed for this job, because the first couple of times I pushed the machine past the door I had to lunge to catch it, so quickly did it roll on its new tyres. This is on smooth tiles with no weight on the bicycle except its own 9.5 kg. How much more do tyres matter on rough tarmac with a rider on-board?

Second. I was fooling around a month ago with my Viking giant friend when I grabbed his Ass (wait!) Saver mudguard and took a tow. (Someone even snapped a pic at one point.) It is astonishing how much resistance to motion a bicycle has even at low speed. At maybe 25 km/h it was all I could do to pinch the mudguard tight enough to pull myself along, but even at 15 km/h the resistance was great – a lot more than I expected. The tyres (Michelin Pro4 Endurance in that case) account for a lot of this.

reohn2
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Re: Moulton SST -- reasons (not) to buy?

Postby reohn2 » 7 Mar 2019, 11:17am

Samuel D wrote: .......How much more do tyres matter on rough tarmac with a rider on-board?......

And that's before we get into wide section,low pressure,supple tyres on 700C's on the same crapmac.
You don't have that option with small wheels as even large tyres on such wheels need a lot of air in them to roll well,so you absolutely need the suspension for comfort.
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Mick F
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Re: Moulton SST -- reasons (not) to buy?

Postby Mick F » 7 Mar 2019, 1:37pm

Samuel D wrote:
Mick F wrote:I have said before, that a larger wheeled machine accelerates faster than a smaller wheeled machine when freewheeling from rest (no pedalling and no push off). I don't know why, but it's true as I'm sitting here.

I believe it’s because the rolling resistance of the small wheels is higher. When freewheeling at near-zero speeds, rolling resistance is practically the only thing checking your motion. This is as plain a proof as you’re going to get that the Moulton’s tyres are draggier, in large part because they’re smaller.

I've been thinking ................. as often am when I'm out cycling. :D

Thought experiment.
Cast your memories back to Meccano and the different sized wheels you could fit on the axles.

Fit four small wheels to a frame and four big wheels onto another. Give them some oil for lubrication and make sure they spin freely. Don't use any tyres, so they are just plain metal wheels.

Place them on a long gentle slope of something smooth, and line them up, then let them roll down.

Which is faster?
Why?
Mick F. Cornwall

igauk
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Re: Moulton SST -- reasons (not) to buy?

Postby igauk » 7 Mar 2019, 4:29pm

All other things being equal larger diameter wheels/tyres have less rolling resistance than small ones. So in MickF's mecanno experiment above the large wheels would be faster provided the slope was long enough to overcome the lower inertia advantage of the smaller wheels (and for the inertia advantage of bigger wheels once they've accelerated) but not so long that the aero disadvantage of the bigger wheels might kick in. It takes less effort to accelerate a small wheel but that advantage is short lived.

Anyway, you can dive in here: https://hadland.wordpress.com/2013/01/15/rolling-resistance-theory-and-practice/
and here: http://wimschermer.blogspot.com/2012/12/bandentest-overzicht-en-correctie-cr.html

Tyre design, pressure, weight, hubs, aerodynamics (of rider position as much as the bike) could all account for the Mercian being faster than the Moulton coasting downhill, even from the off.
Moulton TSR 30

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Mick F
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Re: Moulton SST -- reasons (not) to buy?

Postby Mick F » 7 Mar 2019, 4:41pm

Ok.
I can't disagree.

However, I do have my own thoughts and experiences.
As kids, we built go-karts using pram wheels and wooden frames. Steered with our feet. You know the sort of thing, I'm sure. Happy days! :D

We experimented with different setups. The one thing we noticed PDQ that the length and wheelbase had much do do with the handling. Shorter meant twitchier steering - all else being equal.
Also ............... and the crux of the matter ..............bigger wheels were faster ....... even from the "off" as we lifted off our feet up on a hill.
The bigger the better. My mate had a set of wheels from a big Silver Cross sort of pram. :D Went like a rocket.

It's amazing to think that all those years ago, it was teaching me the physics of wheels, steering and handling.
I can't say I understand, but I know what I know.

Big wheels go faster than small wheels.
Nowt to do with rolling resistance or tyres or tyre pressure ................ though they do affect stuff in the real world on a bicycle.
Mick F. Cornwall

igauk
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Re: Moulton SST -- reasons (not) to buy?

Postby igauk » 7 Mar 2019, 9:30pm

Mick F wrote:Big wheels go faster than small wheels.
Nowt to do with rolling resistance or tyres or tyre pressure ................ though they do affect stuff in the real world on a bicycle.


Agreed, and I think back in the day Alex Moulton only got close to rolling resistance of larger wheels becasue of his special Wolber tyres. Anyway, it's the unfit lump riding the thing that's the biggest problem in my case.
Moulton TSR 30