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Another raked yokes post - DIY

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I am mulling over reducing trail via the yokes, and have no choice but to machine my own.  

If I understand the confusing terminology, "raked" yokes pull the wheel rearward.  Am I correct in that this is done by changing the angle of the fork tube bore in the yokes?  

One could also reduce trail by increasing the yoke offset.  Not my preferred solution as it would need to go from 1.26 to 3.25".  

 

Once on the mill anyway, it is easy and clean to bore a fork tube angle in the yokes at 4 degrees = 2.09" of trail, while leaving the yoke offset stock. 

Stock trail is 4.17" so quite a bit less trail then stock, and I am hoping a sufficient reduction for our winding mountain roads and no freeway use.

I may incorporate race bike style, +/- stem offset bushings so that I can fine tune trail without having to make new yokes.  Finite adjustment only, but not that much more work - the problem is installing them properly so not for the inexperienced

 

A handy calculator:

https://www.rbracing-rsr.com/rakeandtrail.html

 

"If I understand the confusing terminology, "raked" yokes pull the wheel rearward."  No, when you rake the yokes the wheel moves forward,  away from the bike, thereby reducing the trail.

 

The drawing you posted is misleading in that the downward slant angle line is normally parallel to the angle of the forks. The line shown in the drawing is if you changed the angle of the steering head. In that case the line is correct and you moved the wheel forward thus reducing the trail. 

I posted only the after drawing.  Here is the before drawing from Liberty Sidecars I did not post:

 

So the red line is running through the yoke stem axis and not the fork leg?  If I now have it correct, "Raking" the yokes moves the wheel forward while maintaining the same stem geometry.

The method therefore must be boring the fork holes in the yokes at an angle - 4 degrees in my case

 

My first sidecar, and it is no wonder I am confused.............Thanks for setting me straight

 You've got it now.  The stem geometry stays the same, the angle of the fork bore changes, moving the front wheel forward thus reducing trail.

 

 

robert straghan has reacted to this post.
robert straghan

I am only as smart as my internet connection.  Is there an ideal number for trail?  

Once I have this on the mill, the angle can be anything within reason, but I would like to do it right the first time.  I see 2" mentioned in several places but that seems to vary +/- 1/2" depending on application and experience.  My stock trail is 4.17" (106mm) so going to 2.09"with 4 degree yokes is a big trail reduction

My conditions are mountain roads in Thailand, so sometimes a bit bumpy.  No freeway use and probably no more than 110 kph on the straights.  A new sidecar rider, and still trying to learn, so no twitchy steering required.

Bike is a Royal Enfield 650 Interceptor with a Cozy sidecar

  I have experience with  adjustable yokes on road race bikes, whereby the stem angle is adjusted using offset bushings.  Easy at first glance, but a bit fiddly to install and align properly.    As you might imagine, the amount of change is small, but good for fine tuning.  Is this not used in the sidecar world?

 

Uploaded files:
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My 2 cents "do nothing"  It's a small bike with a small light sidecar.  keep it simple sidecatist.

Dave

smitty901 has reacted to this post.
smitty901

What Dave said ^.

The primary - maybe only - reason to reduce trail is to reduce steering effort. With a light bike and car you may be just fine as built. Ride it for a while and see if you really need to modify the rig.

Duncan

smitty901 has reacted to this post.
smitty901

 Have to agree on leave it as is try it mostly a lot of wasted effort

 

Quote from Dave Skudlarek on October 16, 2021, 7:50 am

My 2 cents "do nothing"  It's a small bike with a small light sidecar.  keep it simple sidecatist.

Dave

The adjustable was used by some Harley was one.  They gave up on it.

My 1996 FB 1380cc needed no front end work, Nor did my 2015 750 Harley. The 2020 RGL is ok with no rake but rake would light steering effort some as it did on the 2017.

One more "leave it alone" vote.  You can always change it later if you want.  remember that reducing the trail reduces the steering effort but it also make the steering more "twitchy" and if you're not used to sidecars that won't be an advantage at the start.  When solo riders try my K1100LT/EML rig they all complain that the steering doesn't feel stable.  Experienced sidecar drivers understand and don't worry about it.

 

A

Al Olme Minneapolis, Minnesota

Thanks for the input and will ride it a bit more.  Our roads are twisty at times with lots of switchbacks and I am not a big guy, so  a bit lighter steering would be nice.  A bit lighter is why I was asking about the ideal trail spec on a light bike, with no freeway use

There is a secondary reason for different yokes.  I am currently fitting a larger rotor and 4 pot Brembo calliper to the front and need clearance at the wheel spokes.  I have the calliper fitted now using a rotor spacer and a bit of machine work, but wider yokes would make it a lot simpler and essentially a bolt on mod.  

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