Shortening front forks.
in [Tech]
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From: Greg.Procter on 24 Oct 2009 21:24 On Sat, 24 Oct 2009 07:24:41 +1300, little man upon the stair <macmiled(a)gmail.com> wrote: > On Oct 23, 7:37�am, paul c <toledobythe...(a)oohay.ac> wrote: > >> �I was wondering if you'd have to change >> rake and therefore trail, maybe better high-speed stability is what you >> have in mind but personally I wouldn't want to change the low-speed >> behaviour. > > It's not a good idea to try going faster than about 50 mph on a > scooter�with moderate sized wheels, because the diameter of the tire > not only affects handling, it affects ride quality and traction as the > tire rolls over tiny bumps in the pavement. > > Some of the larger scooters have gone to 18-inch wheels to manage the > bump problem. > My NZeta in the 1960s was quite stable at up to around 70mph. (down-hill, tailwind and prayer ;-) That's really (one of) the reasons I'm interested in rebuilding one. PS handbook claimed 59mph top speed (95km/hr) and I regularly achieved 65mph on the speedo. (eventually) The upside down bathtub structure is/was extremely rigid and the long-travel suspension handled local conditions very well.
From: Greg.Procter on 24 Oct 2009 21:26 On Sat, 24 Oct 2009 08:18:27 +1300, little man upon the stair <macmiled(a)gmail.com> wrote: > On Oct 23, 11:31�am, totallydeadmail...(a)yahoo.co.uk (The Evil Clown) > wrote: > >> You know nothing. > > You prove that you know less every time you challenge an obvious fact. > I've ridden may bikes with much worse handling than the NZeta scooter, eg Harleys, worn Nortons, Triumphs ... Greg.P.
From: Greg.Procter on 24 Oct 2009 21:31 On Sat, 24 Oct 2009 20:34:58 +1300, The Older Gentleman <totallydeadmailbox(a)yahoo.co.uk> wrote: > little man upon the stair <macmiled(a)gmail.com> wrote: > >> On Oct 23, 3:44?pm, totallydeadmail...(a)yahoo.co.uk (The Importunate >> Cottager) pled: >> >> > Nope, sweetie-pie. Wrong again. >> >> It doesn't matter how much you beg, I'm not going to explain the >> effects of >> vibrational frequency on traction as regards rubber tires beyond >> saying that, when the vibration stops, you're about to crash. > > Right. So all small-wheeled bikes are dangerous. > > Do you have a minimum size that you consider to be safe? If so, what? We > need to know. > 27" rims are generally safe! ;-) - Bigger wheels don't fall into big pot-holes as badly as small ones. - Smaller wheels give better acceleration. ;-) - Smaller wheels have less gyroscopic effect. (rider/bike stability) most other effects relate more to suspension than size. Greg.P.
From: little man upon the stair on 24 Oct 2009 22:00 On Oct 24, 6:31 pm, "Greg.Procter" <proc...(a)ihug.co.nz> wrote: > 27" rims are generally safe! Modern sportbikes have tires with an outer diameter of 22 to 25 inches, anything smaller will lose traction on all but billiard-smooth pavement and anything larger than 25 inch diameter will out-track badly when the rider tries to turn into a corner. > - Bigger wheels don't fall into big pot-holes as badly as small ones. > - Smaller wheels give better acceleration. ;-) > - Smaller wheels have less gyroscopic effect. (rider/bike stability) > most other effects relate more to suspension than size. I got heavy into this business several years ago and was the OP that started this thread. http://groups.google.com/group/alt.motorcycle.sportbike/browse_thread/thread/47927af34e5a9560/6476145991efd6f5?hl=en&lnk=gst&q=%22good+vibrations%22#6476145991efd6f5 I got into the vibration problem in the first message and went on to a study of spring preload and how to adjust sag to avoid hobby-horsing over bumps at the desired cruising speed.
From: Greg.Procter on 24 Oct 2009 22:15
On Sun, 25 Oct 2009 15:00:40 +1300, little man upon the stair <macmiled(a)gmail.com> wrote: > On Oct 24, 6:31�pm, "Greg.Procter" <proc...(a)ihug.co.nz> wrote: > >> 27" rims are generally safe! > > Modern sportbikes have tires with an outer diameter of 22 to 25 > inches, anything smaller will lose traction on all but billiard-smooth > pavement That would be a matter of suspension rather than tyre diameter. (down to a point where the radius is greater than about 1/3rd the depth of ruts, holes and corrugations) A lighter wheel can obviously follow irregularities quicker than a heavier wheel. (sprung vs unsprung weight) and anything larger than 25 inch diameter will out-track badly when the rider tries to turn into a corner. Is there something magic about 25"? > >> - Bigger wheels don't fall into big pot-holes as badly as small ones. >> - Smaller wheels give better acceleration. ;-) >> - Smaller wheels have less gyroscopic effect. (rider/bike stability) >> most other effects relate more to suspension than size. > > I got heavy into this business several years ago and was the OP that > started this thread. > > http://groups.google.com/group/alt.motorcycle.sportbike/browse_thread/thread/47927af34e5a9560/6476145991efd6f5?hl=en&lnk=gst&q=%22good+vibrations%22#6476145991efd6f5 > > I got into the vibration problem in the first message and went on to a > study of spring preload and how to adjust sag to avoid hobby-horsing > over bumps at the desired cruising speed. "Hobby-horsing"? (rebound(?)) (Sorry, possible language problem there) Have you considered damping rates??? Regards, Greg.P. |