Karen_Agusta Posted May 30, 2010 Share Posted May 30, 2010 Rake and Trail . In its shortest term it is merely how far away from the frame the tire is. However there is much more to it than that ... it is realted to stability and type of use The best example of extreme rake is the chopper where the tire is several feet from the frame In the real life versions you can see much of the tire is not turning the bike but falling over This also places extreme stress on the front end making traditional hydraulic bump dampening innefective . http://www.robbans-speedshop.com/images/robbans_longfork/longfork1.jpg . . . The "Legend" is the long forks were created by the 70s biker gangs to not fall over when drunk The reality is choppers were made famous by Benny Hardy - The extra long front makes the motorcycle amazingly stable however due to this it turns very poorly For when you turn you are only partially turning as most of the motion flops the tire from side-to-side Therefore stability is gained at the price of a motorcycle with an extreme inability to change direction . . Were the forks have less rake such as they do upon sport bikes The bike turns extremely quickly - reason less rake equals less Trail That is why on superbikes and moto gp race bikes you can see little rake You will notice there is so little rake the tire almost touches the chassis . . . http://media.photobucket.com/image/superbike%20forks/imppbalr/Bike%2520Of%2520The%2520Month/DSC02817.jpg . However there is a great risk involved in doing so That risk is called head-shake or oscillation ... this can toss you This took motorcycle engineers a long time to deal with and prevent it Starting with screw type steering dampners then graduating to hydraulic ones . Screw . http://www.birminghamtoberlin.com/sitebuildercontent/sitebuilderpictures/forum.jpg . . Hydraulic . . . Steering dampners are used to prevent an oscillation of the front tire which is ... the repetitive variation of some measure ... about a central value about a point of equilibrium ... Familiar examples include a swinging pendulum ... The rake and trail you have upon your ride will greatly affect the likelihood of ... and the sensitivity to ... oscillations ... Therefore ... Rake, trail and ride height front to rear ... are very real in the world of motorcycle design ... and are items the industry has been dealing with for very many years now. . Here is an excellent explaination ... http://www.vf750fd.com/blurbs/vibmode.html Though you have seen it every time your grocery store cart has one of its casters wobble For the physics and math remain unchanged from the cart to the bike and it is very dangerous . . With that having been explained we are now at the topic of RAKE and TRAIL ... essentially rake is how far out the forks are set ... choppers have extreme rake where the forks are much closer to horizontal ... sport bikes have very little rake where the forks are much closer to vertical ... Thus we have now explained Rake ... so then ... what is "TRAIL" ... Trail is as follows: If you were to take a long metal rod or bar and you were to hold that rod directly against the forks ... until that rod touched the ground ... and then were take a "plumb bob" and attach it to the axle until it also touched the ground ... if at the point you were to measure the distance between the rod and the plumb bob ... you would have the "trail" measured. . ............................................................................................. ............................................................................................. .. Less Stability .......... Greater Stability .......... Vast Stability .................... .. Meant for Racetracks .... Meant for cruisers ......... Meant for straight line ........... .. Very Fast turn reaction . Slower Turn Reaction ....... Extremely poor turn reaction ...... .. |\ ...................... |\ ......................... | \ ............................... .. |.\ ..................... |. \ ....................... | .. \ ............................ .. |. \ .................... | .. \ ..................... | ..... \ ......................... .. |.. \ ................... | .... \ ................... | ........ \ ...................... .. | .. \ .................. | ...... \ ................. | ........... \ ................... .. | ... \ ................. | ........ \ ............... | .............. \ ................ .. | .... \ ................ | .......... \ ............. | ................. \ ............. .. | ..... \ ............... | ............ \ ........... | .................... \ .......... .. | .......\ .............. | .............. \ ......... | ....................... \ ....... .. | ........\ ............. | ............... \ ........ | .......................... \ .... ---O- = = = --O--------------O-- = = = = = ------O--------O----- = = = = = = = ---------O--- ... Sportbike .................... Cruiser ........................ Chopper ................. ..... Trail ....................... Trail .......................... Trail .................. ............................................................................................. ............................................................................................. . If chassis design, ride height, rake, trail are in order you shall have a good ride ... if not . . . . http://www.youtube.com/watch?v=RmtoOmq3ppw . One note as you can see which helps to explain how this can occur ... as an induction of the wobble ... is a wheelie ... and ... setting the wheel down at an angle ... Upon completing the wheelie once the wheel contacts the ground at an angle ... the wheel immidiately attempts to straigten itself ... However in attempting to snap straight ... the kinetic energy in doing so causes the wheel to bypass straight and go to the other side ... where the front wheel then attempts to go to straight again ... but this time from farther away ... thus the instability and oscillations increase ... until it becomes so great it tosses the rider. . And that is a little information on what is referred to when you read the terms ... "Rake" and "Trail" . Karen Link to comment Share on other sites More sharing options...
barkwindjammer Posted May 30, 2010 Share Posted May 30, 2010 Excellent work Karen, it might be better posted in the workshop section of the forum, anyway, how are you today hot-stuff? Link to comment Share on other sites More sharing options...
Karen_Agusta Posted May 30, 2010 Author Share Posted May 30, 2010 Barkie . Just for reference ... THIS is ... Hot Stuff . http://entiregoods.com/wp-content/uploads/2010/03/sexy-chick-on-motorcycle.jpg . . Though I wish those were me ... I fit (If I can button my leathers) more into this category. . http://roadcaptainusa.com/wp-content/uploads/2009/05/biker-chick.JPG . http://bobandlois.net/bobandlois_files/picturealbums/bikeweek/ladybikers.jpg . Though Barkie ... I do certainly appreciate you putting this forty year old techie dog into that category ... Thank you Barkie ... you are a real sweetie ... I also appreciate your notes on the "workshop" forum ... I am new here and did not realize that posts such as the one I wrote today actually belong there ... Thus I gather that means my other posts do belong there as well. . . . Barkie ... thanks for the reply ... I shall place post of this nature in the "workshop" forum from this point forward ... Most all of it is great to speak with you my fellow rider ... and ... as always ... rubber side down ... Karen . . Excellent work Karen, it might be better posted in the workshop section of the forum, anyway, how are you today hot-stuff? Link to comment Share on other sites More sharing options...
barkwindjammer Posted May 30, 2010 Share Posted May 30, 2010 Rubber in dog speak translates as 'Woof' Link to comment Share on other sites More sharing options...
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