Howard Stevens <hstevens94@xxxxxxxxx> hat am 20. August 2010 um 09:18 geschrieben: > Hey Dirk! > > I made some modifications and it was most interesting. First I reduced the > pivot angle to about 55degrees which reduced the PSI considerably and > improved the ease of turning. Then I reduced it further to 50 degrees and > the PSI ceased altogether! Hooray!! Also the steering was even easier and > the wheel tilting was moderate...I would hardly call it wheel-flop at all. > This is not what I expected...I thought that the less the pivot angle, the > more difficult the steering would be, but it was easier! So it seems you > have solved my problem! I think the geometry and mathematics of all this is > not simple, for many factors come into play, and to varying extents on > different cycles. As you said, the pivot angle was quite significant and so > is the position of the pivot. I also suspect that the Cof G of the > bike/trike is also important as the percentage of the total load on the > front wheel and pivot would also affect the centreing forces and therefore > the PSI. Perhaps bicycles and triicycles also behave differently...does > anyone have any ideas on this?. I have about 35% of the weight on the front > wheel and that seems ok even on steep ascents, but of course on gravel a > steep ascent will lead to wheel slipping. I haven't found much problem with > loading the trike, and suspect that it would make no difference at all, if > it is placed directly over the rear axle. > hmmm. in that case, the lower angle combined with the different pivot placement maybe means that the pivot axis meets your body roughly at the same place like the normal configuration? > In my particular case it seems that it was necessary to decrease the pivot > angle to counteract the PSI induced by the forward position of the pivot. > Perhaps it also counteracted a PSI tendency because only 35% of the weight > is on the front wheel. Another possible factor could be the amount of > negative trail with different pivot angles and wheel sizes. It is starting > to sound a bit like rocket science!!! > Cheers Howard > changing one thing changes everything. there is no perfect world, just a sweet spot somewhere :-) > Hi M Channon or is it McHannon! Yes, your python pivot is pretty much where > mine is, so it is interesting that you don't get PSI. I'm not sure what PIS > is....your not taking the piss outa me are you? Cheers Howard PSI (pedal steering interference) = PIS (pedal induce steering) at some point we had a discussion about which of the two sounded better. we agreed onto this: http://en.openbike.org/wiki/PSI regards, DirkS