The Sportster and Buell Motorcycle Forum - The XLFORUM®
 

Go Back   The Sportster and Buell Motorcycle Forum - The XLFORUM® > SPORTSTER MOTORCYCLE FORUM > Sportster Motorcycle Suspension, Frame, Forks, Handlebars, Fuel Tank, Oil Tank, Fenders
XLF Blogs XLF Arcade XLF Disclaimer/Privacy Statement/Terms Of Use

Notices

Sportster Motorcycle Suspension, Frame, Forks, Handlebars, Fuel Tank, Oil Tank, Fenders Discuss Sportster Motorcycle Suspension, Frame, Forks, Handlebars, Fuel Tank, Oil Tank, Fenders problems, advice, and/or how tos.

Active Threads
0 Opinions (On Bike Considering Buying)
Last Post: webman94
Posted On: 53 Minutes Ago
Replies: 26
Views: 736
0 72 heads, do these look normal?
Last Post: ryder rick
Posted On: 1 Hour Ago
Replies: 9
Views: 140
0 This week on Craig's list
Last Post: ryder rick
Posted On: 1 Hour Ago
Replies: 4,831
Views: 661,912
0 1979 xlh brake pedal woes
Last Post: ryder rick
Posted On: 2 Hours Ago
Replies: 11
Views: 287
0 Sportster fans, tell us why!
Last Post: 1200CustomHD
Posted On: 3 Hours Ago
Replies: 679
Views: 181,475
0 New build. Won't start. Funky compression numbers
Last Post: Heff
Posted On: 4 Hours Ago
Replies: 8
Views: 138
0 Hurricanes
Last Post: XL Ed
Posted On: 4 Hours Ago
Replies: 2
Views: 96
0 2013 48 what would you update first?
Last Post: Tomcatt
Posted On: 4 Hours Ago
Replies: 4
Views: 78
0 Hottie of the day, no nudity.
Last Post: trainman
Posted On: 4 Hours Ago
Replies: 22,099
Views: 2,263,161
0 Hello from Home of HD
Last Post: Tomcatt
Posted On: 5 Hours Ago
Replies: 10
Views: 184
0 79-85 Breather Vent Mod - Adding a Secondary Vent Hose at 6:00 Position
Last Post: Hippysmack
Posted On: 5 Hours Ago
Replies: 20
Views: 713
0 What Marker Lights Are These?
Last Post: FiftySixer
Posted On: 5 Hours Ago
Replies: 7
Views: 267
0 Post your paint questions here!!!!!
Last Post: Hippysmack
Posted On: 5 Hours Ago
Replies: 316
Views: 74,454
0 Turbo Iron 883
Last Post: Cj_
Posted On: 6 Hours Ago
Replies: 55
Views: 3,282
0 What did you do for your sporty Today?
Last Post: duffy
Posted On: 6 Hours Ago
Replies: 7,153
Views: 1,040,771
0 Wanted
Last Post: maltesefalcon
Posted On: 6 Hours Ago
Replies: 3
Views: 114
0 Any Banjo-Playing Sporty Riders here?
Last Post: Crusty
Posted On: 7 Hours Ago
Replies: 34
Views: 1,680
0 Iree's late night cafe
Last Post: rokytnji
Posted On: 7 Hours Ago
Replies: 1,707
Views: 234,666
0 99 1200S Sport Ignition Troubleshooting
Last Post: sportsterdoc
Posted On: 8 Hours Ago
Replies: 22
Views: 340
4 What is the max drilling size in the frame?
Last Post: sportsterdoc
Posted On: 8 Hours Ago
Replies: 6
Views: 255
0 KR style bolt on hard tail for 78 XLCH
Last Post: DirtyHarry68
Posted On: 8 Hours Ago
Replies: 5
Views: 176
0 Show your favorite pic of your bike. just one
Last Post: 1200CustomHD
Posted On: 10 Hours Ago
Replies: 4,793
Views: 1,879,055
12 Lets see the "C's" XLC's that is. Pics Please!
Last Post: Diogenes415
Posted On: 11 Hours Ago
Replies: 1,239
Views: 470,907
0 PLEASE READ THIS Before You Post In 'The BUY - SELL - TRADE Zone'!
Last Post: Folkie
Posted On: 11 Hours Ago
Replies: 1
Views: 126
0 Race Reort: Some Disasters, Some Wins
Last Post: Iron Mike
Posted On: 11 Hours Ago
Replies: 24
Views: 767
0 13" Harley Take Off Air Shocks - $90
Last Post: mrbreezeet1
Posted On: 12 Hours Ago
Replies: 0
Views: 57
0 Progressive Suspension 412-4055C Chrome, 13" Heavy Duty springs, Rear
Last Post: mrbreezeet1
Posted On: 12 Hours Ago
Replies: 0
Views: 127
0 RIDE REPORT During Covid, 13 States & Some Spectacular Riding
Last Post: DK Custom
Posted On: 12 Hours Ago
Replies: 0
Views: 48
0 Carb fastening screw size?
Last Post: Snowplow
Posted On: 13 Hours Ago
Replies: 5
Views: 171
0 Ideal RPM
Last Post: kitabel
Posted On: 13 Hours Ago
Replies: 51
Views: 1,975
More...
Members Birthdays
DaddyJay, sixshooter (73), cartoad2001 (71), Dirty Ernie (65), ncpickman (59), bri1200c (57), pquirk (54), GOTWA (51), gremlinsteve (51), lbowles2 (49), Guess (41), rnaway22es, landon283 (32)
Reply
 
Share Thread Tools Display Modes
  #1  
Old 30th November 2016
Folkie's Avatar
Folkie Folkie is offline
Brass Nut
 
Join Date: Feb 2005
Location: Western Weald
Posts: 46,633
Sportster/Buell Model: XL1200CB
Sportster/Buell Year: 2015
Other Motorcycle Model: CRF250L
Other Motorcycle Year: 2017
Reputation: 17007410
Folkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond repute
Default Ride Height Change With Shock Length Change

Quote:
Originally Posted by splattttttt View Post
How much higher did the rear sit with those 13.5"
My wife rides a super low. I believe the stokers are 10.5
So will the rear come up a whοle 3 inches with these installed.
The shocks are at an angle; if you increase the length of shocks by 3", you will raise the back of the bike by more than 3". Before sag is taken into account, that is.
__________________
Folkie
Super Moderator
South East England Riders



There is nothing at the end of any road better than may be found beside it. Edward Thomas (1878 - 1917)
Reply With Quote
  #2  
Old 30th November 2016
Brad Brad is offline
XL FORUM LIFE MEMBER
 
Join Date: Oct 2006
Location: Phoenix, AZ
Posts: 9,416
Sportster/Buell Model: Sportster
Sportster/Buell Year: None
Sportster/Buell Model #2: 1200C/883C/883R-all sold
Other Motorcycle Model: Dyna FXD-sold
Reputation: 3760079
Brad has a reputation beyond reputeBrad has a reputation beyond reputeBrad has a reputation beyond reputeBrad has a reputation beyond reputeBrad has a reputation beyond reputeBrad has a reputation beyond reputeBrad has a reputation beyond reputeBrad has a reputation beyond reputeBrad has a reputation beyond reputeBrad has a reputation beyond reputeBrad has a reputation beyond repute
Default

Not to be contrary Folkie, but don't you raise the rear less from vertical because of the angle? If we know the angle, I could calculate "x".


Last edited by Brad; 30th November 2016 at 05:15..
Reply With Quote
  #3  
Old 30th November 2016
Folkie's Avatar
Folkie Folkie is offline
Brass Nut
 
Join Date: Feb 2005
Location: Western Weald
Posts: 46,633
Sportster/Buell Model: XL1200CB
Sportster/Buell Year: 2015
Other Motorcycle Model: CRF250L
Other Motorcycle Year: 2017
Reputation: 17007410
Folkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond repute
Default

The angle changes, which is entirely the point.

The horizontal distance between the shock studs is about 7":

Code:
     /|
    / |
10 /  |x
  /___|
    7
By Pythagoras:
x² = 10² - 7² = 100 - 49 = 51
∴ x = 7.14
If we increase the shock length by 3":

Code:
     /|
    / |
13 /  |y
  /___|
    7
The horizontal distance is about the same (actually it's slightly less, due to the swing arm dropping).

Using Pythagoras again:
y² = 13² - 7² = 169 - 49 = 120
∴ y = 10.95
The bike is raised by 3.81".
Reply With Quote
  #4  
Old 30th November 2016
Folkie's Avatar
Folkie Folkie is offline
Brass Nut
 
Join Date: Feb 2005
Location: Western Weald
Posts: 46,633
Sportster/Buell Model: XL1200CB
Sportster/Buell Year: 2015
Other Motorcycle Model: CRF250L
Other Motorcycle Year: 2017
Reputation: 17007410
Folkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond repute
Default

I'll split the last few posts off into a new thread. It'd be a shame to lose them when this ad gets deleted.
Reply With Quote
  #5  
Old 30th November 2016
El Rod's Avatar
El Rod El Rod is offline
Biker
 
Join Date: Oct 2016
Posts: 10
Sportster/Buell Model: XL883N
Sportster/Buell Year: 2011
Other Motorcycle Model: KTM 990 Adventure
Other Motorcycle Year: 2008
Reputation: 10
El Rod is an unknown quantity at this point
Default

The angle begins from the front axle. Bigger vertical change to the rear from shock mount, less toward the front by altering shock length.

Pythagoras didn't ride, but he was a smart dude.
Reply With Quote
  #6  
Old 30th November 2016
Folkie's Avatar
Folkie Folkie is offline
Brass Nut
 
Join Date: Feb 2005
Location: Western Weald
Posts: 46,633
Sportster/Buell Model: XL1200CB
Sportster/Buell Year: 2015
Other Motorcycle Model: CRF250L
Other Motorcycle Year: 2017
Reputation: 17007410
Folkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond repute
Default

Quote:
Originally Posted by El Rod View Post
The angle begins from the front axle.
True, but in practice all we need to concern ourselves with, to show that the height of the rear of the bike changes by more than the shock length change, is the right angled triangle between the shock mounts.

The increase in height will be slightly more than the result of that calculation, because:
  1. The length of the base of that right angled triangle will be slightly decreased, as previously mentioned,
    .
  2. The height of the bottom shock mount will be raised slightly.
BTW, that horizontal distance of 7" is only a rough estimate, based on my bike with 11¾" shocks.
Reply With Quote
  #7  
Old 30th November 2016
Bone's Avatar
Bone Bone is offline
Senior Master Custom Bike Builder
 
Join Date: Jun 2009
Location: Medford, NJ
Posts: 11,020
Sportster/Buell Model: FLHP
Sportster/Buell Year: 2016
Sportster/Buell Model #2: Guzzi V7 Stone
Sportster/Buell Year #2: 2013
Other Motorcycle Model: 18 Guzzi V7D / 11 Duc 696
Reputation: 4213563
Bone has a reputation beyond reputeBone has a reputation beyond reputeBone has a reputation beyond reputeBone has a reputation beyond reputeBone has a reputation beyond reputeBone has a reputation beyond reputeBone has a reputation beyond reputeBone has a reputation beyond reputeBone has a reputation beyond reputeBone has a reputation beyond reputeBone has a reputation beyond repute
Default

I had to go and look at the calculations via an online calculator tool (because it's been too long since I've done that math and I never would have figured it out on my own).

And when I compared some theoretical changes of shock lengths it hit me why this is true seemingly counterintuitive to Brad's example (which is what I was first thinking when I read the OP).

Brad's example, and the one that many of us would probably first assume is true, doesn't recognize that the horizontal distance changes if you set the shock straight up and down. I.E. it's that fixed horizontal distance in the triangle that allows this to be true even though Brad's example is also true. If we stood the shock straight up that vertical distance would change even more, but the vertical distance isn't the shock length in the first place, it's less than the shock length as long as there is any angle.

Thanks Folkie.
Reply With Quote
  #8  
Old 30th November 2016
Folkie's Avatar
Folkie Folkie is offline
Brass Nut
 
Join Date: Feb 2005
Location: Western Weald
Posts: 46,633
Sportster/Buell Model: XL1200CB
Sportster/Buell Year: 2015
Other Motorcycle Model: CRF250L
Other Motorcycle Year: 2017
Reputation: 17007410
Folkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond repute
Default

And Brad's example doesn't say anything about changing the shock length, it's just about standing the same length shock straight up.

BTW, I've demonstrated this several times over the years, the first going back to February 2007! Actually, the very first was in a PM to PΟSTAL_ΟNE in June 2006.
Reply With Quote
  #9  
Old 30th November 2016
bgavin bgavin is offline
Chief Know It All
 
Join Date: Jul 2016
Location: Orangevale, CA
Posts: 429
Sportster/Buell Model: XL1200R, non-CA model
Sportster/Buell Year: 2008
Reputation: 128237
bgavin has much to be proud ofbgavin has much to be proud ofbgavin has much to be proud ofbgavin has much to be proud ofbgavin has much to be proud ofbgavin has much to be proud ofbgavin has much to be proud ofbgavin has much to be proud ofbgavin has much to be proud ofbgavin has much to be proud ofbgavin has much to be proud of
Default

Quote:
Originally Posted by Folkie View Post
The angle changes, which is entirely the point.
The Pythagorean theorem only applies to a right triangle.
Reply With Quote
  #10  
Old 30th November 2016
Folkie's Avatar
Folkie Folkie is offline
Brass Nut
 
Join Date: Feb 2005
Location: Western Weald
Posts: 46,633
Sportster/Buell Model: XL1200CB
Sportster/Buell Year: 2015
Other Motorcycle Model: CRF250L
Other Motorcycle Year: 2017
Reputation: 17007410
Folkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond reputeFolkie has a reputation beyond repute
Default

It's just as well that I'm only talking about right angled triangles then.

The hypotenuse is the shock, and the two shorter sides are down from the top shock mount, and forward from the bottom shock mount, meeting at a right angle.
Reply With Quote
Reply

Bookmarks


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump



All times are GMT +1. The time now is 07:41.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.
XL Forum® - Linson Media LLC