[python] Re: The old qustion of PSI

  • From: George Durbridge <gdurbrid@xxxxxxxxxxxxxx>
  • To: python@xxxxxxxxxxxxx
  • Date: Sun, 20 Jun 2010 09:43:47 +1000

On Sat, 2010-06-19 at 08:56 -0500, Howard Stevens wrote:
> Hi George and thanks for your detailed advice.  Regarding the friction
> damper idea, I understand what you have said, but when cruising along
> a straight road, I would have thought that the static friction would
> not be a problem and then when a turn is required, a quick flick of
> the cam lever would eliminate the friction altogether. I thought it
> was worth a try, but if unsuccessful then I would go to the hydraulic
> ones if I can find a compact way to mount them.

Understood.  It would be interesting to hear how you went.

> My existing Tioga 20x1.75 slicks have been ok on the tarmac, and the
> main reason for changing was the possibility of improving the tracking
> of the front wheel.  I agree that it is probably a long shot and so
> I'll lower my tyre pressure just to see if the extra rubber contact
> noticeably affects the steering. So George, where do you live, and
> what do you ride?  Thanks again for taking the time  Cheers Howard 

It would also be interesting to see how you went with lowering tyre
pressures.  If you want a wider contact patch, you probably want lower
pressure tyres, such as the wider Marathons (47mm) and Big Apples
(50mm).  The Marathon Supreme is fairly wide, also.  All of these can be
run at 70psi or lower.  In switching from 37mm old-style Marathons to
47mm new-style, and before that switching from Comp Pools to Marathon
Slicks, which were about 28mm, I noticed no difference in tracking.

I live in North Fitzroy, and have a couple of MR Swift tadpole trikes,
and my wife has a GT3.  Despite the attractions of centre steering, the
inherent stability of the tadpole layout takes a lot of beating.

I have run various tyres on them: Hookworms (I took them off after a
month, and gave them to a friend, who wore them down to the threads),
several sets of Comp Pools, which were nice tyres between punctures,
Greenspeed Scorchers (similar, even the TR version), Primo Comets
(so-so), Marathon Slicks (light and good for rolling resistance, but
hard riding and liable to puncture), Marathon Plus (puncture-proof, but
heavy) and several sizes of Marathon, which to date have been the best
compromise: nearly puncture proof when new, good rolling resistance and
grip, fairly light, good wear, and the wider ones reasonably soft
riding.  As an experiment, I will fit a set of Big Apples (50mm) to
replace a current set of Marathons (40mm) when they are worn out.  But a
set of 47mm Marathons on the other Swift have been excellent, and look
like lasting 6,000 miles.


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