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 Will a 2000 swingarm bolt up/ fit my 99?
Last Post: Jason's Sporty
Posted On: 18 Minutes Ago
Replies: 16
Views: 261
0 Big bore stroker - the beginning of a 10-year long build
Last Post: Ferrous Head
Posted On: 49 Minutes Ago
Replies: 799
Views: 72,564
0 Good 2 into 2 exhaust?
Last Post: FearTheBeard
Posted On: 1 Hour Ago
Replies: 7
Views: 195
0 Were your parents anti bike?
Last Post: The Crusher
Posted On: 1 Hour Ago
Replies: 17
Views: 209
0 Does Synthetic Engine Oil cause Higher or Lower temps at the oil tank?
Last Post: Sportycus
Posted On: 1 Hour Ago
Replies: 91
Views: 16,971
5 Eye Protection When Riding?
Last Post: Graywolf
Posted On: 1 Hour Ago
Replies: 261
Views: 60,830
0 Gravydog crashed again.
Last Post: BKB
Posted On: 2 Hours Ago
Replies: 87
Views: 3,688
0 What color are your pipes?
Last Post: cazz1000
Posted On: 2 Hours Ago
Replies: 3
Views: 68
0 Cylinder wall scoring after rebuild, can you live with it?
Last Post: IronMick
Posted On: 2 Hours Ago
Replies: 3
Views: 159
0 Relocated Turn Signals
Last Post: 1Scooter
Posted On: 2 Hours Ago
Replies: 2
Views: 54
3 Shaky Dave Recovery
Last Post: SHAKY DAVE
Posted On: 3 Hours Ago
Replies: 26
Views: 956
0 With this fit my 99
Last Post: jordan1200
Posted On: 3 Hours Ago
Replies: 11
Views: 165
0 1200s mid throttle stumble
Last Post: NZstu
Posted On: 4 Hours Ago
Replies: 18
Views: 312
0 KT - 2018 - Hop-along Highway
Last Post: IXL2Relax
Posted On: 4 Hours Ago
Replies: 38
Views: 3,638
12 Lets see the "C's" XLC's that is. Pics Please!
Last Post: Kejobe
Posted On: 5 Hours Ago
Replies: 1,183
Views: 421,573
0 Crusty's Travels
Last Post: Screw Loose Dan
Posted On: 5 Hours Ago
Replies: 1,651
Views: 171,870
3 Transmission Assembly, Tutorial w/Pics
Last Post: Rodzilla
Posted On: 5 Hours Ago
Replies: 73
Views: 50,511
0 Thinking of a fall SE Ohio ride
Last Post: sprink
Posted On: 6 Hours Ago
Replies: 55
Views: 3,115
0 Recommendations for a good parts vendor
Last Post: brucstoudt
Posted On: 6 Hours Ago
Replies: 16
Views: 818
0 Hottie of the day, no nudity.
Last Post: Stairman
Posted On: 6 Hours Ago
Replies: 8,416
Views: 674,815
0 Happy Birthday wandrur!
Last Post: wandrur
Posted On: 7 Hours Ago
Replies: 4
Views: 82
0 Iree's late night cafe
Last Post: Graywolf
Posted On: 7 Hours Ago
Replies: 984
Views: 100,492
0 New England 2018
Last Post: Boudwood
Posted On: 9 Hours Ago
Replies: 225
Views: 11,605
0 Poll for the legalization of cannabis
Last Post: tigger
Posted On: 9 Hours Ago
Replies: 380
Views: 52,359
0 Hi from Queensland Australia
Last Post: juzyHD
Posted On: 9 Hours Ago
Replies: 13
Views: 119
0 What are your thoughts on this 2004 rubbermount Sporty?
Last Post: farmall
Posted On: 10 Hours Ago
Replies: 68
Views: 2,936
0 PLEASE READ THIS Before You Post In 'The BUY - SELL - TRADE Zone'!
Last Post: Folkie
Posted On: 10 Hours Ago
Replies: 1
Views: 2,076
0 FS Stock 2012 Xl1200 and 1275 jugs
Last Post: Folkie
Posted On: 10 Hours Ago
Replies: 1
Views: 142
0 Reflectors...Yeah, or Neh
Last Post: Toejam503
Posted On: 10 Hours Ago
Replies: 159
Views: 36,567
0 Folkie's Rural Rambles
Last Post: Folkie
Posted On: 11 Hours Ago
Replies: 43
Views: 9,145
More...
Members Birthdays
black pearl (74), SDREDD (57), pig (55), BonRu (53), cbass (45), ssm7530 (43), HawkeyeTX, SxysCowboy (35)
Sponsored Links
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: 44,596
Sportster/Buell Model: XL1200CB
Sportster/Buell Year: 2015
Other Motorcycle Model: CRF250L
Other Motorcycle Year: 2017
Reputation: 9735293
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 whole 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's Avatar
Brad Brad is offline
Senior Master Bolter Oner
 
Join Date: Oct 2006
Location: Phoenix, AZ
Posts: 9,414
Sportster/Buell Model: Sportster
Sportster/Buell Year: None
Sportster/Buell Model #2: 1200C/883C/883R-all sold
Other Motorcycle Model: Dyna FXD-sold
Reputation: 3696202
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: 44,596
Sportster/Buell Model: XL1200CB
Sportster/Buell Year: 2015
Other Motorcycle Model: CRF250L
Other Motorcycle Year: 2017
Reputation: 9735293
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: 44,596
Sportster/Buell Model: XL1200CB
Sportster/Buell Year: 2015
Other Motorcycle Model: CRF250L
Other Motorcycle Year: 2017
Reputation: 9735293
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: 44,596
Sportster/Buell Model: XL1200CB
Sportster/Buell Year: 2015
Other Motorcycle Model: CRF250L
Other Motorcycle Year: 2017
Reputation: 9735293
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 online now
Senior Master Custom Bike Builder
 
Join Date: Jun 2009
Location: Medford, NJ
Posts: 10,758
Sportster/Buell Model: 1200Lr
Sportster/Buell Year: 2007
Sportster/Buell Model #2: FLHP
Sportster/Buell Year #2: 2016
Other Motorcycle Model: 13 Guzzi V7 / 11 Duc 696
Other Motorcycle Year: 2013
Reputation: 3153519
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: 44,596
Sportster/Buell Model: XL1200CB
Sportster/Buell Year: 2015
Other Motorcycle Model: CRF250L
Other Motorcycle Year: 2017
Reputation: 9735293
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 POSTAL_ONE 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
Sponsored Links
  #10  
Old 30th November 2016
Folkie's Avatar
Folkie Folkie is offline
Brass Nut
 
Join Date: Feb 2005
Location: Western Weald
Posts: 44,596
Sportster/Buell Model: XL1200CB
Sportster/Buell Year: 2015
Other Motorcycle Model: CRF250L
Other Motorcycle Year: 2017
Reputation: 9735293
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



Sponsored Links
All times are GMT +1. The time now is 05:57.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2018, vBulletin Solutions Inc.
XL Forum® - Linson Media LLC