On 16/05/2013 21:27, Zebee Johnstone wrote:
> What effect does suspension have on speed?
"It depends".
As Kimble noted, over grot surfaces it makes the bike more sure-footed,
plus the lack of up-and-down for bike and rider as you hit the bumps
saves a lot of energy and that translates to potentially quicker. So
down a hill on a ruined sub-B back road in the middle of nowhere, quite
a bit. Around a velodrome, ~ damn all. In between there'll be a spectrum.
It's also the case that different suspensions are made for different
jobs. The sort of thing you find on a downhill MTB is there to soak up
enormous hits while the sort of thing you find on a Moulton is to help
even out small imperfections on normal roads. Both are good at their
own job and pretty hopeless at the other's. For the road, a properly
designed[1] road-going suspension will potentially aid speed but the
better the road the less significant it'll be.
> I have no idea as to what, besides weight, affects speeds on a 'bent.
>
> Recline I suppose but how much does that matter?
It's aerodynamics in general. The Kingcycle Hachi was less reclined
than the Optima Baron, for example, but still contrived better
aerodynamics with a rather radical chain routing and over-the-shoulder
frame (I suspect Mr. L can provide us with better details on this sort
of stuff).
> Some combination of seat angle and tube angle affecting both rider hip
> angle and aero? Hand position?
Ultimately, if you want to go really fast you put on a fairing.
> Bacchettas seem most common in the US (surprise) and StreetMachines
> and other Euro bikes in Europe (surprise again) so dunno if there are
> any races or trials that have pitted one against the other.
Human Power Vehicle Association races have done this, but after earlier
days when folk would turn up on anything the fields appear to be getting
more specialised. Again, Mr. Larrington is the man for proper info here.
Pete.
[1] I've been talking about suspension, as opposed to "suspension", as
found on BSOs. That enables your BSO to go "boing" in an undamped and
not optimally useful way. AFAICT good suspension is non-trivial and
needs decent design and engineering input to come up with a well working
system, not just sticking a spring on it.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net
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