Thanks for the comments Ed. The bike in the picture is just an example,
it's not my bike. So far my bike is just a pile of tubing and some good
intentions. Well, there's also some wheels, a motor, and a couple of other
things.
Your comment about dirt ruts has got me thinking. Those fast dragbikes only
run on fairly smooth asphalt, and I know that the dirt at El Mirage and the
salt at Bonneville can develop ruts. So, probably I should be looking at
something that's more of a compromise between a dragbike and a streetbike.
Maybe a rake angle in the low to mid 30's? As Keith has pointed out, the
Hossack front end is very adjustable. So it shouldn't be to big of a
problem to dial in a few more or less degrees of rake to fine-tune the
handling, if need be.
Henry
At 08:05 PM 1/11/2001 -0700, Ed Van Scoy wrote:
>Henry,
>Very interesting front-end, but, from the photo, I only see about 20 Deg
>of rake -
>This assumes you are measuring from the "relocated" steering axis through the
>vertical CL. I say "relocated as usually the steering axis is measured
>through the
>steering head. Now, if you drew a straight line through the steering head,
>the new
>line, bisecting your CL, would be about 45 deg. & your trail would be
>about twice
>what you have now (I did this by holding a ruler up to the screen to get
>straight
>lines, so this ain't real scientific) A street bike typically has 3-6
>inches of
>trail, and my rough guess is 16-20 in of trail if measured from steering
>head. As
>you know more rake/trail, the more tendancy to go in a straight line, but
>I would
>sure hate to have to wrestle a super-long front-end out of a rut in the dirt.
>Having babbled away all that, what I am trying to say is (caution! opinion
>follows!) from the picture shown, the rake appears quite less than 40-45
>deg and
>the trail about 6 in? All in all, appears to be a heavy-steering bike. As
>a reality
>check get a picture (mental or otherwise) of a top-fuel bike and compare
>the rake
>they have to the BMW photo. The front end on the digger will appear much
>longer.
>Ed
>
>Henry Deaton wrote:
>
> > The bike shown uses a draglink between the front forks and the handlebars.
> > The main advantage I'm looking for is improved aerodynamics. Since the
> > forks are solid, I can use streamlined tubing. I'm also hoping to keep the
> > front of the bike lower than I could with standard forks. Ideally I'd use
> > some kind of hub-center steering, so the Hossack is a compromise that
> > should be more aerodynamic than telescopic forks and also simpler, easier,
> > and less expensive to build than a hub-center front end.
> >
> > The design has some other advantages too, like maintaining the same rake
> > and trail throughout the full range of travel and no dive when you brake,
> > things that are more important to bikes that need to turn or brake for
> corners.
> >
> > BTW, I had to ask about the steering too when I first saw this front end.
> >
> > Henry Deaton
> > SF, CA
> >
> > At 04:18 PM 1/11/2001 -0600, Keith Turk wrote:
> > >Henry... I am throwing this opinion out there based on nothing but my
> > >concept of how to go fast and try and be semi reliable....
> > >
> > >I went to the Website and checked out the front end.... try as I might I
> > >couldn't see how the steering was applied to the front end.... nor could I
> > >see the real benefits from it over a simple triple clamp/ conventional
> Folk
> > >arrangement....
> > >
> > >I guess what I am trying to say is could you enlighten me as to the
> > >advantages of a system this complicated....
> > >
> > >Keith ( big fan of the KISS principal )
> > >
> > >----------
> > > > From: Clay, Dale <Dale.Clay@mdhelicopters.com>
> > > > To: 'Henry Deaton' <hdeaton@verio.com>; List Land Speed
> > ><land-speed@autox.team.net>
> > > > Subject: RE: Motorcycle Front-End Geometry
> > > > Date: Thursday, January 11, 2001 4:01 PM
> > > >
> > > > Henry,
> > > >
> > > > I don't have much experience with "lay down" bikes but those
> numbers are
> > > > pretty close to what fuel bikes run and they're up around 230 for blown
> > > > fours and 200 for twins.
> > > >
> > > > With the limited amount of travel required, I doubt you need as
> > >complicated
> > > > a suspension as that, but if you want to play with it ...
> > > >
> > > > Dale
> > > >
> > > > Hey Dick J. is that your 300K mile bemmer in the photo?
> > > >
> > > > -----Original Message-----
> > > > From: Henry Deaton [mailto:hdeaton@verio.com]
> > > > Sent: Thursday, January 11, 2001 2:44 PM
> > > > To: List Land Speed
> > > > Subject: Motorcycle Front-End Geometry
> > > >
> > > >
> > > > I'm finally ready to start building my electric LSR bike. Here's what
> > >I've
> > > > got planned so far:
> > > >
> > > > Hossack-style front end, 1.5" travel:
> > > > http://www.eurospares.com/tfoale/mmjpg/tfbmw.jpg
> > > > solid rear end
> > > > 3.5x17 front wheel, with a 120/60ZR17 tire
> > > > 4.5x18 rear wheel, with a 160/60ZR18 tire
> > > > wheelbase around 70" (bike needs to fit on my 4x8 trailer)
> > > > weight without rider about 600 lbs, with rider around 760 lbs.
> > > > Forklift motor
> > > > CVT snowmobile transmission
> > > > 270 lbs AGM batteries, 120 volts
> > > >
> > > > Speed should be in the 150 to 175 mph range? (well, ya gotta have a
> goal,
> > >
> > > > right?)
> > > >
> > > > I was wondering if anyone on the list has any thoughts about front-end
> > > > geometry. I'm thinking of using a front rake around 40 to 45
> degrees, and
> > >
> > > > about 8 to 10 inches of trail. That's what a guy that builds dragbike
> > > > frames recommended to me.
> > > >
> > > > Any comments or questions would be appreciated. I've done some drag
> > >racing
> > > > with electric bikes in the past, but this LSR stuff is pretty new
> to me.
> > > > Mainly looking for tips on how to build a bike for straight-line
> > >stability
> > > > at El Mirage and Bonneville.
> > > >
> > > > BTW, only 115 days until El Mirage.
> > > >
> > > > Henry Deaton
> > > > SF, CA
|
