stfu
XS650 Enthusiast
Well I have been reading a lot lately about Rake and Trail as I am in the process of doing it myself and thought I'd pass a bit of it along. Seems all the studying I have read is somewhat incorrect.
While the traditional Rake and Trail calculators we find online give a ball park estimate of the trail, it is still not accurate. There is still another measurement to take called "True Trail". This is a perpendicular line taken from the steering axis to the the center of the contact patch of the tire (vertical line with front axle down to contact patch). In short we don't measure from ground point of steering axis line to the vertical centerline as we've seen in a lot of online documentation. Which may explain the varying and somewhat inconsistent explanation of how we can rake to 38-40 degrees and still remain drivable.... for example Gordonscotts bike. IF we factor this new measurement in we find our trail is not as long as we have come to believe/calculate. Which lends credence to the documentation found in early XS specs showing the "Trail" to be at 3.9".
As posted by XSLeo http://www.xs650.com/forum/showthread.php?t=6539
In this thread the factory documentation states "Trail" of 3.9". If we measure it for "False Trail" we get 4.47" which is confirmed by the online calculations. But measure the true trail and your just under 4". Hmmmm.... 3.9" of "True Trail" maybe?
In summation the "True Trail" is what we should be focusing on and use to figure drive-ability. A good/optimal "True Trail' can be anywhere from 1.5" (twisty sport bike) - 5" up to 6.2" (if HD FLH is a "True Trail" spec). While I believe 40 degrees of rake exceeds this 5-6.2" figure, as with Gordonscotts bike, it is not the 8.95" "Trail" the calculator would have us believe.... Probably in the upper 6-7"ish "True Trail" range. Which may be why Gorrdonscotts comments tell us it handles/rides better than one would think.
I would love to get some other thought from everyone here. So chime in if you got em'
While the traditional Rake and Trail calculators we find online give a ball park estimate of the trail, it is still not accurate. There is still another measurement to take called "True Trail". This is a perpendicular line taken from the steering axis to the the center of the contact patch of the tire (vertical line with front axle down to contact patch). In short we don't measure from ground point of steering axis line to the vertical centerline as we've seen in a lot of online documentation. Which may explain the varying and somewhat inconsistent explanation of how we can rake to 38-40 degrees and still remain drivable.... for example Gordonscotts bike. IF we factor this new measurement in we find our trail is not as long as we have come to believe/calculate. Which lends credence to the documentation found in early XS specs showing the "Trail" to be at 3.9".
As posted by XSLeo http://www.xs650.com/forum/showthread.php?t=6539
In this thread the factory documentation states "Trail" of 3.9". If we measure it for "False Trail" we get 4.47" which is confirmed by the online calculations. But measure the true trail and your just under 4". Hmmmm.... 3.9" of "True Trail" maybe?
In summation the "True Trail" is what we should be focusing on and use to figure drive-ability. A good/optimal "True Trail' can be anywhere from 1.5" (twisty sport bike) - 5" up to 6.2" (if HD FLH is a "True Trail" spec). While I believe 40 degrees of rake exceeds this 5-6.2" figure, as with Gordonscotts bike, it is not the 8.95" "Trail" the calculator would have us believe.... Probably in the upper 6-7"ish "True Trail" range. Which may be why Gorrdonscotts comments tell us it handles/rides better than one would think.
I would love to get some other thought from everyone here. So chime in if you got em'
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