[python] Re: AW: Re: Front Suspension



olaf@xxxxxxxxxxxx schrieb:


On 25 aug 2006, at 09.24, Ronald W. Hongsermeier wrote:

Hi Dirk and listies,
comment below in text.

dirk.bonne@xxxxxxx schrieb:

Thorsten Borm wrote:

A very simple way to have something like an suspension is this: I use "Schwalbe Big Apple" with 50mm and 2,5 bar pressure on both wheels. They work very good at rough roads and little potholes. At flat roads there is nearly no noise and they are rolling very easy. And - they are looking fine!

I have been eying these tires for some time too, but not enough place for 50mm tires on my current python :-( On this (dutch) website: http://www.ligfiets.net/accessoires/type.php3?id=336 it is said that "best" pressure should be at 4bars. Bert Hoge made rolling tests for some tires (unfortunatly I have not the article and its seems not to be available online). And the curve rolling resistance vs. pressure for big apple has some kind of "knik" at 4 bars * below 4bars the rolling resistance curve decreases much with pressure increase (i.e. not linear with pressure). * above 4bars the rolling resistance does not decrease much more, and above are not more comfortable.

this is probably a result of designing the tires for a "sweet spot" in rolling resistance and comfort at the given parameters. As with all engineering, you can shoot for some targets but you can't hit all targets at exactly the same time. ;-)



I think it is useless talking about sweet spots and specific air pressure levels as long as you don't include a specific weight. It is all about how the tyre deforms when meeting the tarmac and the size of this deformation varies if you weigh 60 kg or 90 kg, if you carry equipment or not. And how heavy the bike is.

It wasn't soooo useless-- (you do understand smileys and friends? eg.: ":-)" is a smiley face ) it got you to talk about specifics, which interest me very much. I am a neophyte when it comes to the hard facts. I have now ridden 6 wedge-formed bikes mostly into the junk pile and am interested in view of increasing back problems in a reclining position while pedaling. It is impossible for me to have access to the engineering parameters that guided the people at Schwalbe. I was simply trying to make a generalization about design. However my observation is correct and is in fact underlined by your more specific case explanation.


A good advice given on another list is to inflate tyres with the specific load on the bike (i.e. yourself plus bags) then inflate until there is no deformation when you sit on the bike. If done carefully, there will still be some "suspension" left for potholes.

The trick is finding an optimum pressure level, balancing between comfort and minimum rolling resistance. Otherwise we would ride on steel wheels.

I have experience trying to brake with a front rim on both concrete and asphalt, thus I have another parameter which speaks against the use of steel wheels ;-) However, steel wheels and tracks work very well in dirt, but because of weight considerations are not too practical for power requirements in the 125 watt avg. comfort range.


Hm, a good Stones album comes to mind ...

I think of something more like Phil Keaggy's "The wind behind my back..." and if I'm on steel wheels, then I want a water cushion under my behind, even on a recumbent.


Olaf 

regards,
Ron



.

(thats what they say on that page). dirk ============================================================ This is the Python Mailinglist http://www.freelists.org/list/python Listmaster: Jürgen Mages jmages@xxxxxx To unsubscribe send an empty mail to python-request@xxxxxxxxxxxxx with 'unsubscribe' in the subject field. ============================================================ 

regards,
ron


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Olaf Johansson

Visseltofta 1200 A
283 95 VISSELTOFTA

Tel +46 (0)479 - 40141
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olaf@xxxxxxxxxxxx

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