CBR 600 rear suspension evaluation - Wrist Twisters
Thread Tools Display Modes
post #1 of 6 Old 03-18-2007, 10:09 PM Thread Starter
Old, Bold rider
robtharalson's Avatar
Join Date: Jan 2007
Location: Aurora, Colorado
Posts: 2,432
Rep Power: 1

Awards Showcase
Donation Veteran Community Leadership 
Total Awards: 3

CBR 600 rear suspension evaluation

I have extensively evaluated the '03 - '04 CBR 60 rr rear shock link setup and find it to be a work of art not only from the general concept of it, but also due to it's adjustability if you are creative and know what you are doing. An evaluation follows.

Look at cbr linkage diagram, drawn directly from a transparent view from (I assume) Honda advertising copy. As the suspension compresses, the distance G-D increases, drawing point E forward and moving point F upward, compressing the shock absorber. As angle G E D increases toward 90 degrees, the rate of shock compression decreases, making a falling rate. When angle G E D is 90 degrees, mechanical advantage is at minimum (cosecant 90 degrees = 1), giving maximum suspension compliance. If spring / damping rates and sag are adjusted properly for the rider's style, track, and tires, this "sweet spot" will correspond to the desired suspension position while in a corner, increasing control at this critical time. In order for this to function properly, compression damping must be carefully dialed in. A too low compression damping rate will allow the swingarm to move past the sweet spot , then try to return, causing a pogo effect as the optimum comes and goes until equalibrimum is established, if indeed it ever does before exiting the corner changes the dynamic. Too high compression damping will delay settling in, causing insufficient suspension movement entering the corner and a vague or unsettled feel midcorner. Either condition points to compression damping being considerably more important than rebound as least as relates to entering corners. Rebound takes over when exiting corners, preventing excessive rise rate and possible loss of traction when on the throttle while still leaned over.
This also explains why longer lowering links mess up the handling: the sweet spot occurrs so far near bottomed out that it essentially never happens under normal conditions, which makes spring preload and damping rate adjustments very critical and fussy. A shorter shock would have the opposite effect, causing the sweet spot to move toward topped out, essentially useless. I suppose a combination of the two might work, but would require very careful selection of parts to pull it off.

What does this mean to the rider who wants to lower his CBR while maintaining its sharp handling? It seems to me that the only way to adjust the ride height without effecting link geometry would be by changing point G, the frame attachment point: perhaps using a selecton of plates which would bolt to the chassis with differing G positions. I have not looked at the frame with an eye toward modification, but it would not surprise me if Honda cast in bosses for just this sort of setup. Caution here: loads are very high.


If it has already been done, it is safe to assume it is possible to do it.
On the other hand, if it has not been done never assume it is impossible to do it.
------- Rob --------
robtharalson is online now  
Sponsored Links
post #2 of 6 Old 03-20-2007, 08:03 AM
Hastatus Prior
eazy e's Avatar
Join Date: Jan 2006
Posts: 1,517
Rep Power: 1

Awards Showcase
Total Awards: 1


+ $5

eazy e is offline  
post #3 of 6 Old 03-20-2007, 08:17 AM
I am BATMAN!!!
justintyme73's Avatar
Join Date: Apr 2006
Location: Ft. Collins CO
Posts: 4,660
Rep Power: 1

Awards Showcase
Outstanding Restoration Donation Donation 
Total Awards: 3

double whoa....

"He was a wise man who invented Beer"--Plato
justintyme73 is offline  
post #4 of 6 Old 03-20-2007, 09:20 AM
Join Date: May 2006
Posts: 1,379
Rep Power: 0
I am just glad you didn't say sinusoidal.

motorwerks919 is offline  
post #5 of 6 Old 03-20-2007, 11:01 AM
ragdoll's Avatar
Join Date: Jan 2006
Location: Seattle, WA
Posts: 7,274
Rep Power: 1

Awards Showcase
Total Awards: 1

Very true. The setup is awesome in every way except that when dialed in it doesn't become "optimally" compliant until you are in or near that 90 degree 'sweet spot'. Although if you aren't riding it hard enough to even be able to take advantage of this and not able to even get the linkage to crank that far in in the first place you probably wouldn't need to worry about the compliance. And if that's the case, you probably never dialed in your bike in the first place and shouldn't buy such a cool bike.

Good write up dood.

It's "equilibrium"

'02 RC-51
'10 Unicycle

ragdoll is offline  
post #6 of 6 Old 03-23-2007, 03:31 AM
woodyeee's Avatar
Join Date: Mar 2007
Location: united kingdom
Posts: 406
Rep Power: 1
Rob you got ezmail

woodyeee is offline  

Quick Reply

Register Now

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

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


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

Email Address:


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 Off
Pingbacks are Off
Refbacks are Off

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