sugar bear springer on sporty

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curt
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Re: sugar bear springer on sporty

Post by curt »

krymis wrote:
rudog wrote:Sorry to all...I'm not buyin' it!!!

If the x/y/z relationship of the axle to the steering neck is fixed, the shape of the forks can have no effect on how the front tire moves when the steering axis is rotated. There's an unknown quantity that I need to know.

If the rocker pivot is dropped below the axle, that would mean that the rocker is angled upward. This would limit minimum trail to normal ride height, any motion would increase trail. Maybe something???
thew axle is not the gyroscopic rotational axis. the contact patch of the front tire is. the axle comes into the picture as that is the connection between the wheel/tire combo and the steering axis. Not only do you need to look at that aspect you also need to take into account the perceived weight of bike being on the axle in one aspect and the lighter feel of the weight being moved under the axle and forward (moved rather from the horizontal 0 centerline to below that and towards the vertical 0 centerline.

I do believe that i may need to do a video on how I build and how two different frontends react even though they have similar numbers.


id love to see that
ever notice when you hit somethin or someone with a hammer you feel instantly better
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Maxthegardener
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Re: sugar bear springer on sporty

Post by Maxthegardener »

krymis wrote:So the story goes that i got this springer for a song and a dance. I found a counte's customs take-off sugar bear springer. i bought it for the fact of wanting to blueprint a sugar bear springer (the last springer i needed to blueprint for my important springer blueprint collection). I bought it blueprinted it and sold it. a few weeks later the guy asked if i could buy it back as he lost his job. no problem to me. I then decided i would put it on a bike. it went on a 95 883 sporty that needs to be chopped. So here is the beginning stages of a sporty frame built to an existing frontend. I was not sure of what rake or up and out this frontend was built for so i had to mount a wheel and set the rocker bolts to 10-15 degrees off horizontal to get the stretches and rake set. i used a stock sporty wheel/tire(19 rim with a 100/90/19) rather than a 21 like sugar bear calls for. all that did was bring the overall up stretch down by 3/4". So right now the bike sets at 43-44 degrees rake and the top of the bottom tree is 36 3/8" off the ground. that is a 4 up off of softail standards. its about an 8 to 8.25 up on the sporty. I still need to figure out the out and the rear stretches. i think i am doing a 4" rear stretch and a 2 out front stretch. once all of that is figured out i will cut the frame for the hardtail and then do the backbone and upper wishbones to make a nice straight line to the axle blocks.
Image
Image
like that Springer ......Id wanna sharpen the Rockers.....


Yeah sorry carry on :popcorn:
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Re: sugar bear springer on sporty

Post by krymis »

rudog wrote:Sorry to all...I'm not buyin' it!!!

If the x/y/z relationship of the axle to the steering neck is fixed, the shape of the forks can have no effect on how the front tire moves when the steering axis is rotated. There's an unknown quantity that I need to know.

If the rocker pivot is dropped below the axle, that would mean that the rocker is angled upward. This would limit minimum trail to normal ride height, any motion would increase trail. Maybe something???
rudy,

five words we came up with and i will be putting in the handbook word for word is" suspension optimization for the rider". Great call and i hope we got somewhere with all the info flying around.

For others following rudy and i were talking about similar things at different points in the formulas and measurements that for him would not feel comfortable but for me would and vice versa. A few things to take away from this build is 1. not everyone likes the same thing or the same feel. 2. think of the frontend in 2 ideas one as all individual parts to make a frontend and two the frontend is part of the whole picture to make a bike therefore every item on that bike has an effect on the way the suspension or lack there of will work
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rudog
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Re: sugar bear springer on sporty

Post by rudog »

Rocker-On!!!
Jeff L
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Re: sugar bear springer on sporty

Post by Jeff L »

rudog wrote:
If the rocker pivot is dropped below the axle, that would mean that the rocker is angled upward. This would limit minimum trail to normal ride height, any motion would increase trail. Maybe something???
........That would depend on the shape of the rockers.Its easy to see on that SB springer that the pivot point is well below the axle while giving full range of movement of the wheel.I cannt see how the change in trail numbers as the wheel moves up & down is a factor as that movement happens at such a rate of speed that it wouldnt be felt.
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rudog
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Re: sugar bear springer on sporty

Post by rudog »

The angle of the axle to the rocker pivot is the important factor. The shape of the rocker is not. Krymis "knows" a hell-of-alot more about this angle than I do. The phrase "dropping the forks below the axle" is a secondary effect of what's really going on.

What I'm buying is that "for this type of front end, proper tuning of the suspension will result in the forks being below the axle."

Suspension tuning/optimisation involves alot of factors: weight, COG, trail/rake, and all the others words that people throw around without being able to explain. But, I'll let Krymis be the authority in this thread. After all, IMO "A man with an experience can never be held hostage by a man with an opinion."
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curt
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SELF INTRODUCTION: hi everyone its me from the old bord hopeing to see everyone come here and all the newcomers . lets make this as good as the old one or even better . lookin foreward to seeing everyones projects continue and ill be continueing mine too
Location: utica new york

Re: sugar bear springer on sporty

Post by curt »

at least u guys make it intresting to read :popcorn:
ever notice when you hit somethin or someone with a hammer you feel instantly better
Jeff L
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SELF INTRODUCTION: Hey...I live in South Jersey (the Super Fund State) work as an Operating Engineer local825.Besides bikes I love to fish the surf.I have my current & seemingly endless project a BSA 750 Rocket3, a 72 Honda CB750,79 Kawasaki KZ1000, 48 Simplex, & a 62 Norton Atlas engine
Location: South Jersey

Re: sugar bear springer on sporty

Post by Jeff L »

Thats fine dude.... I was just trying to add to the discussion & maybe learn something myself.All I was doing was commenting on what you said...maybe I read it the wrong way who knows...but to me you saying the rockers would angle upwards if the forks were below the axle would mean that the front legs would be highsr then the rear.Which isnt the case at all, given the shape of the rockers.And it was said that all parts contribute to the whole equation....which means you cannt disregard rocket design (shape).I read somewhere maybe it was in the Horse...that the trail numbers on those long Sugar Bears springerts dont addd up,but they work.(Ill have to look through a few past issues & see if I can dig it up
Changing the shape of the Earth...1 bucket at a time...IUOE local 825 top of the food chain
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Maxthegardener
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SELF INTRODUCTION: Name is Max living in scotland ,and building my first bike, Which is derived from a buellM2 Cyclone..Started with an engine and a Drop seat frame wich was made to my spec by a more experienced builder. would like to learn more about the skills and techniques required to build a frame so I value being a member here...Cheers Max
Location: Angus, Scotland

Re: sugar bear springer on sporty

Post by Maxthegardener »

With all the increased leverage on the suspension ...allowing the wheel to maximise the effect of the springs....are they upgraded in any way...
and on another note...
I just cant help but think you'd experience a lot of understeer in some conditions...and if you used a front brake....even under normal conditions get a lot of front end dipping...
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rudog
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Re: sugar bear springer on sporty

Post by rudog »

Jeff L wrote:Thats fine dude....
I'm just a man with an opinion. And, yes, trying to keep it interesting.

Max, I emailed the Bear about the springs. He does use the same springs. If you consider the leverage of the angled rocker(measured from pivot to axle) you'll have less force applied to the springs than a horizontal rocker.
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Re: sugar bear springer on sporty

Post by gww25 »

First of all The contact patch of the tire with the pavement is not the mathematical point of rotation for cycle forks. That point is usually slightly lower and behind the axle even on a set of hydraulic forks. Secondly the lower this point is in relation to the axle the less flop the forks will have. Dropping the rear pivot point in relation to the axle as on the SB springer accomplishes this and reduces trail at the same time. You can build what I call 'dropped rockers', like the SB type that have any trail you want, the actual shape of the rocker is not important, that's just an artistic thing. Dropped style rockers give the rider the impression of 'power steering' because you only need to move the forks a few degrees to accomplish a large movement at the wheel hub compared to a bike having conventional rockers.
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SELF INTRODUCTION: Hey dan it chris (krymis) from the CBH board. thanks for opening this back up. hope to have a project to show the build here. BLAH BLAH BLAH BLAH BLAH and so on and so forth. The book of revolations and worlds ends and shit like that.....

Re: sugar bear springer on sporty

Post by krymis »

when you talk to bear remember he is of the 60-70 mind set that there needs to be mystery around what you build so you have an edge. i have spoken to him many times at length about his springer and have gotten half stories worded in such a way that the line is not a lie but would leave you to an opposite conclusion. This is the exact reason i chose to buy an authentic sugar bear, and dispell the myths. his springs are not custom wound...i checked them against my paughco and gary's paughco springs and they are exact matches. Wire, diameter length, everything.his retainers nothing spectacular. the rockers look really cool and say that they "LOOK" like they have 0 trail. However they do not. they o bide by the same physics and geometric rules as any other good handling springer. remember SB uses offset trees so that plays a role in the trail calc and the look of 0 trail. On top of all that some of his springers don't look just right at the steering stem area. the cause is simple...he doesn't use raked trees or any newfangled setups he simply uses raked neck cups. you know those things people always forget about. They are good for up to 5* of additional rake in the neck. only 3 is recommended. Remember that raked trees create less trail and raked cups makes more trail. there are many more little secrets that SB does but honestly gary's rude crude is just as good setup properly and less hassle to make.
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Re: sugar bear springer on sporty

Post by gww25 »

Here's a little sketch of two bikes having 45-degree rakes showing some the relationship between regular and dropped style rockers.
Image
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rudog
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Re: sugar bear springer on sporty

Post by rudog »

No fare using pictures, Gary :D

My argument is a cart/horse cause/effect regarding the description of the math. Ther's more in that picture than a dropped axle. The movement of the wheel around the steering axis is defined by the perpendicular distance to the axle, but, that distance also "dictates" trail. You can not change one without the other.

If you stick to the statement that handleing will get better by increasing this distance (axle perpendicular to steering axis) then you allow the misconception that negative trail is OK.

If, however, you make the statement that minimising trail will make a bike handle better, it still alows for a dropped axle.
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Location: Murphy, Texas
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Re: sugar bear springer on sporty

Post by gww25 »

I'm not sure what you're saying exactly but keep in mind that you can make trail be whatever you want it to be by changing any one of three to five different factors but trail isn't really all that important to bike handling as demonstrated by Tony Foales various experiments and really should not completely dictate the design of a pair of forks. In fact flop can be more of a problem, especially on a bike with a heavy front wheel and poor balance with the chassis center of gravity location. The use of a dropped rocker or the design of a dropped rocker is not set by using trail at all. You can have a dropped rocker on a zero trail bike of one having 8-inches of trail. The huge advantage of the dropped style rocker is to minimize flop by 'tricking' the bike into thinking that it has a very small diameter front wheel. Other than that there really isn't anything very special about using them on a springer or a spirder.
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