Mick F wrote: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.
Big wheels good, small wheels better.
Two saddles best!