CHOP CULT HOME
Email Password
Search
Page 1 of 2 12 Last
  1. #1

    Join Date
    Oct 2019
    Posts
    15

    Default Need Help Choosing Springer length and Rockers

    I bought this old raked out 85 FLT a couple of months ago. It had sat for a while. Been working on it, got it running pretty good now.

    It's 45 degree rake with 6 over forks. I'd like to put a mid to budget priced (wide type) springer front end on it.

    I want to raise it up about 2 inches too. I'm 6'3" and around 260. Bike looks too small for me being this low. Once I get front raised up I'll install taller shocks to level it out.

    Do I go 10 over with springer? What length rockers do I need? Do rockers need to be specific to rake?

    Please Help!
    Attached Thumbnails Attached Thumbnails IMG_6783.jpg   IMG_6784.jpg   IMG_7957.jpeg  
    Last edited by Booneman; 10-12-2019 at 8:41 AM.

  2. #2

    Join Date
    Oct 2019
    Posts
    15

    Default

    Note: I have put taller bar risers and widend foot pegs since picture. Previous owner was a bit shorter than myself. so I had to adjust a few things.
    Last edited by Booneman; 10-12-2019 at 8:17 AM. Reason: added comments

  3. #3
    Senior Member

    Content on this page requires a newer version of Adobe Flash Player.

    Get Adobe Flash player


    Join Date
    Dec 2017
    Posts
    2,269

    Default

    Are the trees raked on that frontend? Just wondering if your 45 degree rake is the forks or the frame neck.

  4. #4

    Join Date
    Oct 2019
    Posts
    15

    Default

    The frame neck is raked. The tree is not. About 10 inches of Trail the way it is now. (kinda fun to ride that way, lol)

    Note: 21 inch front wheel
    Last edited by Booneman; 10-12-2019 at 9:48 AM.

  5. #5
    Senior Member

    Content on this page requires a newer version of Adobe Flash Player.

    Get Adobe Flash player


    Join Date
    Sep 2011
    Posts
    1,898

    Default

    What about de raking it some to achieve a stance closer to your vision?

    Something else you could try is putting the bike on a small stand, then sliding the tubes down in the trees to extend the front end and see how much it changes.

  6. #6

    Join Date
    Oct 2019
    Posts
    15

    Default

    Thanks for the response.

    I actually bought it with the intent of putting a springer on it with longer forks.

    I like the 45 degree rake with swing arm frame.

  7. #7

    Join Date
    Oct 2019
    Posts
    15

    Default

    Quote Originally Posted by brooklynbomber View Post
    What about de raking it some to achieve a stance closer to your vision?

    Something else you could try is putting the bike on a small stand, then sliding the tubes down in the trees to extend the front end and see how much it changes.
    I actually did try your idea of playing around with forks while on a stand. Kinda hard to tell how this will translate to springer though. It's gonna sit a bit differently, depending on what rockers I end up with.

    I'm not sure to go 8 over or 10 over? I don't want to raise it up too much just an inch or two.

    I see Twisted Choppers has a good selection of springers in different price ranges. Just not sure on what length fork and rocker to order.

  8. #8
    Senior Member

    Content on this page requires a newer version of Adobe Flash Player.

    Get Adobe Flash player


    Join Date
    Dec 2017
    Posts
    2,269

    Default

    Just need to search for 'how to determine springer length', or go directly to the manufacturer you want to buy the springer from.

    How To Measure For Springer Forks
    Click image for larger version. 

Name:	SPRINGER-MEASURE-EXH-1.jpg 
Views:	0 
Size:	54.5 KB 
ID:	97612
    http://www.chopperhandbook.com/springer-measure.htm


    Determine what length springer front end
    Click image for larger version. 

Name:	vcregcqwe1-2-300x206.jpg 
Views:	82 
Size:	13.1 KB 
ID:	97613
    https://www.meatballsspringers.com.a...ger-length-2/#


    How to Determine Front Ends Length and Rake
    Click image for larger version. 

Name:	fork_length.jpg 
Views:	1 
Size:	26.5 KB 
ID:	97614
    https://www.demonscycle.com/length-rake

  9. #9
    Senior Member

    Content on this page requires a newer version of Adobe Flash Player.

    Get Adobe Flash player


    Join Date
    May 2018
    Posts
    877

    Default

    Forget all the 8 over,10 over etc.,etc,.
    Trail is achieved differently on springers and telescopic forks.

    After you get the springers and if it has too much "flop " THEN get longer rockers for the springers.
    But keep the trail in check.
    Also when ordering springers make the measurements then add two inches to account for the weight of the motorcycle.
    Also different tires can have a taller aspect ratio or lower aspect ratio. This can help you fine tune the height.

    Make your measurements based on the manufacturers recommendations.
    Call them if you have to.

  10. #10

    Join Date
    Oct 2018
    Posts
    245

    Default

    The length of the rockers is too general a criterion... how they position the axle in relation to the springer's legs when loaded also matters.

  11. #11
    Senior Member

    Content on this page requires a newer version of Adobe Flash Player.

    Get Adobe Flash player


    Join Date
    Sep 2012
    Posts
    11,074

    Default

    Quote Originally Posted by Skjoll View Post
    The length of the rockers is too general a criterion... how they position the axle in relation to the springer's legs when loaded also matters.
    I think he's over thinking it myself..............

  12. #12

    Join Date
    Oct 2019
    Posts
    15

    Default

    Quote Originally Posted by Skjoll View Post
    The length of the rockers is too general a criterion... how they position the axle in relation to the springer's legs when loaded also matters.
    This is part of what I'm wondering. Seems like rockers would be shaped differently depending on rake? This would also effect on fork length needed?

  13. #13

    Join Date
    Oct 2019
    Posts
    15

    Default

    Quote Originally Posted by TriNortchopz View Post
    Just need to search for 'how to determine springer length', or go directly to the manufacturer you want to buy the springer from.

    How To Measure For Springer Forks
    Click image for larger version. 

Name:	SPRINGER-MEASURE-EXH-1.jpg 
Views:	0 
Size:	54.5 KB 
ID:	97612
    http://www.chopperhandbook.com/springer-measure.htm


    Determine what length springer front end
    Click image for larger version. 

Name:	vcregcqwe1-2-300x206.jpg 
Views:	82 
Size:	13.1 KB 
ID:	97613
    https://www.meatballsspringers.com.a...ger-length-2/#


    How to Determine Front Ends Length and Rake
    Click image for larger version. 

Name:	fork_length.jpg 
Views:	1 
Size:	26.5 KB 
ID:	97614
    https://www.demonscycle.com/length-rake
    Yes, I have looked at some of these charts. I guess I need to determine my desired FH measurement first.

  14. #14
    Senior Member

    Content on this page requires a newer version of Adobe Flash Player.

    Get Adobe Flash player


    Join Date
    Sep 2012
    Posts
    11,074

    Default

    Quote Originally Posted by Booneman View Post
    This would also effect on fork length needed?

    Nope................ unless the rockers are a foot long straight up...........

  15. #15

    Join Date
    Oct 2019
    Posts
    15

    Default

    Quote Originally Posted by Tattooo View Post
    Nope................ unless the rockers are a foot long straight up...........
    The rockers need to be specific to the angle of rake?

  16. #16
    Senior Member

    Content on this page requires a newer version of Adobe Flash Player.

    Get Adobe Flash player


    Join Date
    Sep 2012
    Posts
    11,074

    Default

    Quote Originally Posted by Booneman View Post
    The rockers need to be specific to the angle of rake?
    Nope your wrong................. Like I said before not unless the rockers are a foot long..............

    Your really over thinking all this rake of the frame, length of a front end in relation to the rocker length..........

    It's not as complicated as your trying to make it out to be...........

    Set your frame at the angle you like, buy a front wheel that you want to run, get a tape measure and have at it............

    Stop talking about it and get to work..........
    Last edited by Tattooo; 10-23-2019 at 7:08 PM.

  17. #17
    Senior Member

    Content on this page requires a newer version of Adobe Flash Player.

    Get Adobe Flash player


    Join Date
    Dec 2017
    Posts
    2,269

    Default

    If ya wanna learn more about rocker design, here ya go, lots of reading on this site:

    Chopper Builder's Handbook
    Springer Fork Rocker Designs

    "...What this article addresses is the specific design considerations for building custom Springer Rockers as a part of fine-tuning the handling characteristics of a typical Springer fork system.
    Keep in mind as you read along that what we're going to talk about here applies to Chopper front-ends. By that I mean forks that set on a 35-degree rake or more and forks that are extended at least 6-inches over stock.
    Don't try to apply what follows on stock or Bobber type front ends..."

    Click image for larger version. 

Name:	pivot1.jpg 
Views:	0 
Size:	27.0 KB 
ID:	97847
    The sketch above shows a fairly typical off-the-shelf Springer setup for a bike having a 45-degree rake angle and running a 21-inch front wheel while the sketch below shows the same hypothetical bike set up to run a Springer using dropped rockers.

    Click image for larger version. 

Name:	pivot2.jpg 
Views:	0 
Size:	29.5 KB 
ID:	97848
    Notice the 1.5-inch difference in the location of the wheel pivot point (PR) between the two fork sets and the 3-inch difference in trail. The effective length of the rockers is identical so there is no change in the spring rates for the two different forks even though the 'sword' type dropped rockers look far larger. The forks in the lower sketch will handle significantly better than the forks shown in the upper sketch.

    https://www.chopperhandbook.com/rockers.htm

  18. #18

    Join Date
    Oct 2019
    Posts
    15

    Default

    Quote Originally Posted by TriNortchopz View Post
    If ya wanna learn more about rocker design, here ya go, lots of reading on this site:

    Chopper Builder's Handbook
    Springer Fork Rocker Designs

    "...What this article addresses is the specific design considerations for building custom Springer Rockers as a part of fine-tuning the handling characteristics of a typical Springer fork system.
    Keep in mind as you read along that what we're going to talk about here applies to Chopper front-ends. By that I mean forks that set on a 35-degree rake or more and forks that are extended at least 6-inches over stock.
    Don't try to apply what follows on stock or Bobber type front ends..."

    Click image for larger version. 

Name:	pivot1.jpg 
Views:	0 
Size:	27.0 KB 
ID:	97847
    The sketch above shows a fairly typical off-the-shelf Springer setup for a bike having a 45-degree rake angle and running a 21-inch front wheel while the sketch below shows the same hypothetical bike set up to run a Springer using dropped rockers.

    Click image for larger version. 

Name:	pivot2.jpg 
Views:	0 
Size:	29.5 KB 
ID:	97848
    Notice the 1.5-inch difference in the location of the wheel pivot point (PR) between the two fork sets and the 3-inch difference in trail. The effective length of the rockers is identical so there is no change in the spring rates for the two different forks even though the 'sword' type dropped rockers look far larger. The forks in the lower sketch will handle significantly better than the forks shown in the upper sketch.

    https://www.chopperhandbook.com/rockers.htm
    Yeah! Thanks! This is what I think I need. I want to get rockers that will reduce my trail.

  19. #19
    Senior Member

    Content on this page requires a newer version of Adobe Flash Player.

    Get Adobe Flash player


    Join Date
    Sep 2012
    Posts
    11,074

    Default

    Quote Originally Posted by Booneman View Post
    Yeah! Thanks! This is what I think I need. I want to get rockers that will reduce my trail.
    Why?????? Do you have a reason for that statement????????

  20. #20
    Senior Member

    Content on this page requires a newer version of Adobe Flash Player.

    Get Adobe Flash player


    Join Date
    Dec 2017
    Posts
    2,269

    Default

    Remember back in the hey day (or was it haze-daze...hard to remember, oh da fog...) of chopper building...who thought about trail...that was something rough you rode your bike down, before there were actual roads, if you were asked about your trail, the answer was 'rough and dusty'
    ...when the neck was just cut from the bottom and a 3-finger rake was built and welded together...like shown in this Big Bike article from 1970: http://www.choppersrule.com/chopper_...rake_neck1.asp (no mention of trail there...)
    and the springer legs were cut and lengthened with Ford radius rods or whatever was layin' around...or round steel slugs were screwed into the top of the fork tubes to lengthen 'em...
    Click image for larger version. 

Name:	fork slugs.jpg 
Views:	1 
Size:	125.6 KB 
ID:	97955
    Wow...are they making them again?!: " These fork tube extensions replace the stock fork tube caps and are made from solid, hi-grade steel with a chrome finish. Available for most 39, 41 and 49mm applications in 2" (5 cm), 4" (10 cm) and 6" (15 cm) length...Fits 39mm forks on 1987 to present Sportster, 1987 thru 1994 FXR and 1992 thru 2005 Dyna": https://catalog.zodiac.nl/en/catalog...be-extensions/

    Then there were raked trees and extended tubes, (or fork slugs) stuck on stock bikes with stock rake, like the Allied 10-10 kits:
    Click image for larger version. 

Name:	Allied 10-10 kit.jpg 
Views:	0 
Size:	21.3 KB 
ID:	97959
    and negative trail was the result...okay for slow speed but don't hit a bump when flying down the road (further along than just a trail)
    Click image for larger version. 

Name:	Negative trail, CHB.jpg 
Views:	0 
Size:	51.8 KB 
ID:	97960
    Of course the were many manufacturers of extended springers and girders like AEE, Amen, Butts, California Cycle, CCW, Columbus, Cycle Shack, Defiance, Durfee, D&D, Dick Allen, EME, Finch, Franks, Fury, Gyro, Harman, Jammer's, KDM, Ness, P&P, Paughco, Randy's, SIE, SB&F, SugarBear, T&S Sales, Wayne, Wheel Specialties...t name a few...
    Then there were highways, and discussions turned to rake and TRAIL (not just a rough and dusty path)...with calculations and generalizations of what is acceptable trail (is that almost a rule - a chopper rule...come on - there ain't no rules!)...so now, through places like The Chopper Handbook, trail is a real thing, a thing to consider, to tune even, to get the best handling for you, for the rake and length of extended front end you got or want. SugarBear has a big rocker thing that is designed on trail:
    Figure 16 represents a stylized sketch of what we used to call 'Scimitar' rockers that were popularized in the early sixties and still built today by Sugar Bear and a few others:
    Click image for larger version. 

Name:	Rocker, scimitar, Old School Springer_img_15.jpg 
Views:	0 
Size:	32.6 KB 
ID:	97957

    This particular chart was set up to determine the rocker geometry for forks where I wanted to maintain 3-inches of trail regardless of what the neck rake angle happened to be. On the full-scale chart it was easy to interpolate down to 1-degree of accuracy.
    Click image for larger version. 

Name:	trailchart3.jpg 
Views:	0 
Size:	63.9 KB 
ID:	97958
    Those semi-circular arcs you see drawn between the axle and the rear pivot pin hole having nothing to do with the rocker shape but are there just to make it easier to understand what axle locations go with what pivot location...Ironically a guy who actually was really good at mathematics and geometry did the same exact thing but did it empirically by actually building a mockup in his shop consisting of steel bars drilled with dozens of holes. Through trial and error he tried scores of various rocker/rake relationships and physically measured the amount of flop for each and every possible arrangement of parts and hole locations. This guy was Sugar Bear and that's how he came up with his incredible rocker designs.
    https://www.chopperhandbook.com/rockers.htm
    Handling characteristics involve hundreds of variables as we mentioned earlier and the trail value is but one of those factors. For more definitive information about trail as it effects road bikes I urge you to read the book entitled 'Motorcycle Handling and Chassis Design' by Tony Foale.

    For the average Chopper builder Trail is strictly an indicator of relative 'forward' or 'dynamic' stability at various speed ranges and if your bike is within the 2 to 9-inch range you're in the same group as about 98% of all other Chopper owners. https://www.chopperhandbook.com/rake.htm
    Last edited by TriNortchopz; 10-27-2019 at 12:27 AM. Reason: img insert

Share This



Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Log in

Log in