What's suspension got to do with a bike's cornering? - Sportbike Forum: Sportbike Motorcycle Forums
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 15 (permalink) Old 12-21-2001, 04:23 PM Thread Starter
 
Join Date: Jun 2001
Posts: 269
What's suspension got to do with a bike's cornering?

sorry to be stupid, but i dont see how the suspension can affect how a motorcycle takes curves. i mean, the bike is leaning so what difference does it make how far the forks go down? i just dont see it...

so if it makes such a big difference, what should i set mine at to handle better? softer or harder? how much softer or harder? do i need to buy something or is the stock adjustment enough? thanks
dash is offline  
Sponsored Links
Advertisement
 
post #2 of 15 (permalink) Old 12-21-2001, 07:43 PM
 
Join Date: Jan 2000
Posts: 503
well basically it does the same thing when u r straight up & down.. keeps the wheels in contact w/the road.

it may not look like it & it may not be logical but the susupension still works leaned over.

there is so much to know & so many variables in sportbike suspension that it would take days to post about it.. here is a link that is not technical at all & should shed a little more light on the subject..

http://www.directparts.com/static/goose/suspension.htm
SpeedPhreak is offline  
post #3 of 15 (permalink) Old 12-21-2001, 07:58 PM
Registered User
 
DaDuck748's Avatar
 
Join Date: Nov 2000
Location: East Bay, CA
Posts: 2,512
Send a message via Yahoo to DaDuck748
Re: What's suspension got to do with a bike's cornering?

Quote:
Originally posted by dash
sorry to be stupid, but i dont see how the suspension can affect how a motorcycle takes curves. i mean, the bike is leaning so what difference does it make how far the forks go down? i just dont see it...

so if it makes such a big difference, what should i set mine at to handle better? softer or harder? how much softer or harder? do i need to buy something or is the stock adjustment enough? thanks
There are no stupid questions if you're asking to learn. Before you go out and spend a bunch of money, read all you can, talk to as many people "in the know" as possible. Information is (for the most part) free. Just keep an open mind, since every rider likes their suspension and uses it differently. Once you've learned as much as you can stand , then you'll have the information you need for suspension tuning. At that point, you can then introduce Mr. Hammer to Mr. Piggy.

SP, good URL. I'll have to bookmark it.
DaDuck748 is offline  
 
post #4 of 15 (permalink) Old 12-21-2001, 08:12 PM
Moderator
 
Grok's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC Canada V9E 1C8
Posts: 397
Lightbulb NOT a stupid question!

This is a question that every serious tuner, engineer, racer asks. For every person you ask you'll get a slightly, sometimes very different answer.
Here is a quick idea of the issues.
Chassis geometry and suspension are two unique and distinct components of a motorcycles handling. In an ideal world, suspension wouldn't affect chassis geometry, nor the reverse. But that has always been the burning issue in bike design and set-up!
If everything would be smooth and flat, suspension would be undesirable, Thats why in F1, the smoothest tracks get the shortest travel suspension.
The rougher things get, the more travel you need to maintain a semblence of control at high speeds.
We need to keep the wheels on the ground, the chassis in a stable state, and keep the bike comfortable, therefore controllable.
Unfortunately, when wheels go through their suspension travel, all the careful calculated chassis numbers (Rake, trail, C. of G. to name a few) change. THIS IS NOT GOOD.
Suspension setup also effects feedback to the rider.

I hope this helps explain the importance of suspension and technical problems it creates.

Set up your suspension? Here are a few important basic points.

First and very important step, set the sag!
To do this right, you need 2 assistants. The burly one holds the rear of the bike, balanced upright, with you in your normal riding position. You may need a few attempts to get comfortable, it takes a bit of tutoring to get the assistant to only keep you from tipping and at the balance point, so that he hardly needs to apply pressure on the bike at all. When he's got that point sussed, "assistant 2" measures from the fork wiper to the bottom triple-tree, then measures up from the rear axle to a grab rail bolt or something. Now get off, and fully extend the suspension and let "assistant 2" re-measure, using the exact same reference points. Now subtract the smaller numbers from the larger. This gives you you your sag! This number should be between 1/4 to 1/3 (25 to33%) of your total travel. This should be a one-shot-deal unless you or the bike gains or loses weight!
Now check that your tire pressures are correct and go riding! Fiddle with your damping settings a couple of clicks at a time. A Couple of hints:
If you get a sharp jolt over lips/potholes, less compression damping.
Pogo ride/topping out, more rebound damping.
If a rapid succession of bumps makes things feel rougher/pumping down, less rebound.
If you are at the limits of adjustability in your quest for nirvana, use a heavier/lighter suspension fluid.

I hope this Helps out! Seasons greetings!

Try it...........You'll like it!

Last edited by Grok; 12-21-2001 at 08:15 PM.
Grok is offline  
post #5 of 15 (permalink) Old 12-23-2001, 01:36 AM
Registered User
 
ssallber's Avatar
 
Join Date: Oct 2000
Location: Hendersonville, TN USA 37075
Posts: 241
Grok's summary is pretty good. From your location we probably ride the same roads. I have helped set up suspension on many bikes at TWO with the owners grinning big time afterward from teh results. Setting sag and rebound/compresion damping make a big difference. Hard to explain in a short note but there is a lot of magazine articles on how to do it. Basically it will get the attitude of the bike set so the geometry of the components is correct, rake & trail, swing arm angle and to allow the full use of your suspension travel and keep both front & rear working together. Picture this, what if you had no oil in the front forks and set up for a turn. The front end would dive big time then picture the rest. If you have never set up the suspension you probably do not know any different. Afterward in a lot of cases you will wonder how you could ever have ridden the old way.
Steve S.

Steve Sallberg
Anderson, SC
ssallber is offline  
post #6 of 15 (permalink) Old 12-23-2001, 04:01 AM Thread Starter
 
Join Date: Jun 2001
Posts: 269
Re: NOT a stupid question!

Quote:
Originally posted by Grok
, "assistant 2" measures from the fork wiper to the bottom triple-tree, then measures up from the rear axle to a grab rail bolt or something. Now get off, and fully extend the suspension and let "assistant 2" re-measure, using the exact same reference points. Now subtract the smaller numbers from the larger. This gives you you your sag! This number should be between 1/4 to 1/3 (25 to33%) of your total travel. This should be a one-shot-deal unless you or the bike gains or loses weight!
Now check that your tire pressures are correct and go riding! Fiddle with your damping settings a couple of clicks at a time. A Couple of hints:
If you get a sharp jolt over lips/potholes, less compression damping.
Pogo ride/topping out, more rebound damping.
If a rapid succession of bumps makes things feel rougher/pumping down, less rebound.
If you are at the limits of adjustability in your quest for nirvana, use a heavier/lighter suspension fluid.

I hope this Helps out! Seasons greetings!
so whats the fork wiper and bottom triple tree? also, once i get my sag, you say it should be 25-33% of my total travel, whats total travel? one other thing, is the damping setting the things that are adjustable on my bike, like the turny things at the tops of the hadlebars and the one at the rear of the bike? i dont think i understand
dash is offline  
post #7 of 15 (permalink) Old 12-23-2001, 05:19 AM
Moderator
 
Grok's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC Canada V9E 1C8
Posts: 397
Dash, I would find the "total travel" numbers for your machine from the dealer, these numbers represent the total distance the suspension allows wheel to move. May as well ask those other questions while your there at your friendly dealers.
Sounds like you need a "mentor" to help with some of these basics. A knowledgeable biker-buddy can save you a lot of grief. Be sure to listen well and don't ask the same questions over and over. This will insure his/her help will continue.
There is always a forum like this too! But words, (in my case particularly!) often come up short in these more involved technical matters.
Keep on asking questions.

Try it...........You'll like it!
Grok is offline  
post #8 of 15 (permalink) Old 12-23-2001, 05:37 AM Thread Starter
 
Join Date: Jun 2001
Posts: 269
k, ive got my owners manual here just reading about how to adjust suspension and stuff. theres a spring preload adjuster and rebound damping adjuster for each of the front and rear. also the rear has a compression damping adjuster. the manual says for all of these that i should turn them to "Soft for a light load and smooth road conditions" or to "Hard for a firmer ride and rough road conditions." i read the article posted earlier in this discussion and what i got from it was that for a more performance setting it would be set at towards Hard so as to stand up to the pressure put on the bike in corners. but im not riding on anything real bumpy! cuz thats what the owners manual told me to do.

i guess my question is should the settings be set harder or softer for better performance in corners, not track but canyon roads, etc. i dont care a bit about comfort on the highway cuz i dont ride there. ive read so much on this lately that it seems like everything is contradictiong everything else...
dash is offline  
post #9 of 15 (permalink) Old 12-23-2001, 05:55 AM
Registered User
 
DaDuck748's Avatar
 
Join Date: Nov 2000
Location: East Bay, CA
Posts: 2,512
Send a message via Yahoo to DaDuck748
Good reading...

Dash (and others),

Here's an awesome book on... well, performance tuning, written by Kenvin Cameron, for non-rocket scientists. It helped me understand a lot of things about overall performance tuning. It's only like $15, or just pick one up from your local motorcycle shop (most carry it, in the Bay Area, CA anyway).

http://www.amazon.com/exec/obidos/AS...204927-1246935
DaDuck748 is offline  
post #10 of 15 (permalink) Old 12-23-2001, 09:32 AM Thread Starter
 
Join Date: Jun 2001
Posts: 269
ok i think i understand everything now, i just dont know where to measure the front sag. you told me where but i dont know where those places are.
dash is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Sportbike Forum: Sportbike Motorcycle Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may 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
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome