Come On Eileen!....tanks for the memories!

[crazypj]

Re: Come On Eileen!....MONO-PROGRESS!

Did you plot arc of movement for lower mount?
At 90 degree you get max mechanical advantage, so, as its compressing its getting easier to push on shock, (unless its going 'over-center'? )
I would have to draw it out to check my gut reaction.
Do you have a 2.2~2.5:1 leverage ratio? (looks about that from pics)


PJ

 

[tWistedWheelz]

Re: Come On Eileen!....MONO-PROGRESS!

MY HEAD IS SPINNING!!!!I NEED A STIFF DRINK!!!!!
I think I have planned enough, I was very confident, but I respect PJ's knowledge enough to second guess myself now! I am moving on with my current plan and hope for the best! I am done planning and ready to start welding! If my plan is wrong, I will just find out the hard way!
I am going to fix a drink, or two, or three! How ever many it takes to ease my thoughts of this design, maybe six!

Thanks guys, like I needed another excuse to get drunk!

 

[crazypj]

Re: Come On Eileen!....MONO-PROGRESS!

Not a big deal if its wrong, just get a multi rate spring from an older bike ;D.
Everything looks good, plenty strong enough.
You may never notice which way rate is going, as long as wheel stays on the ground and you can't feel suspension working its good (if you feel suspension working, it isnt )
First one I did (CB400F, around 1985) I got right by accident.
Ended up moving front mount about 1" to clear carb linkage which accidentally put it in perfect position for rising rate (good idea to check motor AND ancillaries fit before welding things solid )
May be able to move front mount poosition to change rate?

PJ

 

[tWistedWheelz]

Re: Come On Eileen!....MONO-PROGRESS!

I put the motor in her last night and it looked good, I think it will clear just fine, but I have no carbs at the moment! :-\ Thanks for your help, could you give me some clues on what bikes had 11" multi-rate shocks in case I need to go that route! No working tonight, just drinking and looking at her and hoping it all turns out good!

Cheers mate!

 

[crazypj]

Re: Come On Eileen!....MONO-PROGRESS!

you need spring length, wire diameter, inside diameter of coils (so it fits over shock body) actual working coils not so important as you can 'change' things.
Don't have many springs lying about to measure but I'll see what I can do in next few days.

PJ

 

[chrisf]

Re: Come On Eileen!....MONO-PROGRESS!

Did you plot arc of movement for lower mount?
At 90 degree you get max mechanical advantage, so, as its compressing its getting easier to push on shock, (unless its going 'over-center'? )
I would have to draw it out to check my gut reaction.
Do you have a 2.2~2.5:1 leverage ratio? (looks about that from pics)

PJ

PJ:

Yes, at 90 degrees, one gets maximum mechanical advantage. But why you say, "as its progressing its easier to push on the shock..." is beyond me. It's either really awkward grammar (and a misunderstanding) or wrong.

Quick disclaimer here: I did not run the numbers for Brandon; I explained the theory.

As his wheel rises, it will get progressively more difficult to push the spring. There is no need to get a multi-rate spring to compensate for a design error because I don't think one exists. You ask him to plot the arc [of] movement of the lower mount. He did that--so to speak. To simplify, the damper angle to lower mount angle is 90 degrees at maximum compression. To use your words: the point at which it receives maximum mechanical advantage.

I really think you mean well ( I certainly listen!), but sometimes that gets confused by odd sentence structure and poor elaboration...and perhaps you don't look closely at the photos.

Brandon:

If you really want to put this to bed, remove the spring on the coilover and mount it up. Then raise the wheel in 1/2" increments. Each time you raise it, measure the distance travelled on the damper and write it down. Do this until the damper hits the bump stop. Plot out the distance change and my gut tells me you'll get between 18-20% rising rate.

--Chris

 

[crazypj]

Re: Come On Eileen!....MONO-PROGRESS!


I'm not an engineeer and I didn't stay at Holiday Inn (but I am tired )

I'll check back tomorrow

PJ

 

[tWistedWheelz]

Re: Come On Eileen!....MONO-PROGRESS!

I am too drunk amd tired right now to do any mechanical work, plotting, or measuring! I have come to the conclusion that it will be constructed as it is planned now, after 4 glasses of bushmills, I have looked it over and over! It looks good to me right now!

Bushmills, solves problems!

I am pitching this for thier new slogan!

 

[hillsy]

Re: Come On Eileen!....MONO-PROGRESS!

And if it doesn't work out, you can change the slogan to "Bushmills causes problems....."

;D

 

[squirley]

Re: Come On Eileen!....MONO-PROGRESS!

Nice looking build.
I just did the same to an H1 and it seems to be just fine...and it should be, ducati did cantilever suspensions for years
it looks like you made your lever arm long enough, so keep going with your original idea...

 

[biker_reject]

Re: Come On Eileen!....MONO-PROGRESS!

Heyyy, I'd sure like to see some H1 pics!

 

[squirley]

Re: Come On Eileen!....MONO-PROGRESS!

Im not meaning to highjack the thread so I will delete these if you want me to...on that note here is the H1

By null, shot with iPhone 3GS at 2010-01-10

 

[biker_reject]

Re: Come On Eileen!....MONO-PROGRESS!

Holy shite. I knew I wouldn't be disappointed! That is something! Purist be damned. Modern components on vintage bikes gives me a chubby.

 

[scm]

Re: Come On Eileen!....MONO-PROGRESS!

... with the shock completely compressed I come to perfect 90 degrees angle between the plane of the shock and the plane of the shock mount in relation to the swingarm pivot point.

Very well, if so you'll get a rising rate geometry anyway.
But in your pix it looks like the 90° were at full extended shock !?

At full extension my angle increases to beyond 100 degrees.

To me it looks quite rectangular...

Is that not the principle of rising rate theory? As the shock compresses under load the resistance of the shock should increase due to the angle. Am I wrong here?

You're perfectly right, the principle is to start with any angle and
then move towards 90°... Once again, to me it just seems your
pix don't match your description...

... let's blame it on the camera! ;D

Best regards and good luck!

Sven

 

[scm]

Re: Come On Eileen!....MONO-PROGRESS!

Yes, at 90 degrees, one gets maximum mechanical advantage.
But why you say, "as its progressing its easier to push on the
shock..." is beyond me.

Well I'm not PJ, but have a look at the pix:
the first one with fully extended shock looks
like a perfect 90°, doesn't it?
Now along its travel, the angle increases, and
this is why PJ mentioned "as its progressing its
easier to push..."
It works like an elbow lever, i.e. degressive.

To cure this the shock could be shifted down
at least until the lower mount matched with the
"pivot" edge of the triangle (or further).
Requires a new bracket of course, but then we
had a geometry starting (full extended) with let's
say 75° increasing to 90° at compression and
that would be the desired rising rate.

Best regards
Sven

 

[chrisf]

Re: Come On Eileen!....MONO-PROGRESS!

Shit! I see what you guys are saying.

Brandon may have gotten it right and the pictures don't show it. Basically, you have to put the 'fully compressed" block in the system and raise the wheel up. At that point, the damper angle to mount angle should approach 90 degrees (88-89.8 or so). I personally would not go full 90 because the bump rubber (bump stop) will absorb some of the angle.

If you look at sven's picture, the furthest circle to right is where the damper should be at full droop. The middle circle is where damper should be at full compression.

Like I said, you may have gotten it right and the pictures are skewing things. Based on our phone conversation, you're spot on. Thanks for illustrating that Sven.

--Chris

 

[tWistedWheelz]

Re: Come On Eileen!....MONO-PROGRESS!

Well it apears that the pic with the MS paint overlay does show the wrong angles, however I will get back in the shop and get you a pic of the square in place at full extention to show you the angle. I know its right.

 

[Jfishsolevibe]

Re: Come On Eileen!....MONO-PROGRESS!

Im not meaning to highjack the thread so I will delete these if you want me to...on that note here is the H1

By null, shot with iPhone 3GS at 2010-01-10

This is my favorite bike on the entire forum. Hands down. Cant wait to see it done.

Cant wait to see Eileen done too!

 

[chrisf]

Re: Come On Eileen!....MONO-PROGRESS!

Well it apears that the pic with the MS paint overlay does show the wrong angles, however I will get back in the shop and get you a pic of the square in place at full extention to show you the angle. I know its right.

perfect! I figured as much. Glad to hear you're on your way.

--Thanks, Chris

 

[forcefanajd]

Re: Come On Eileen!....MONO-PROGRESS!

lol i think everyone is over thinking this whole process, while im sure it would handle better with everyones recommendations taking into consideration there are always variables which are overlooked when building a bike at home. so that being said, cut the template you have out of some sheet metal, tack weld the thing on your swing arm, and sit on the damn thing to see how it feels to you, my bet is that youll be more than happy with the results and it will be an improvement over your stock shocks no matter what. i dont know too much about suspension geometry so this is what i would do.