Rear shock resources

[ac3_snow]

Have been looking a little into this for the last couple of days as I am thinking it may be worth swapping my 21 year old shock for something a little newer that might still work! here is a piece on the gixxer forums I found with a bit of info on lengths etc,

http://www.gixxer.com/forums/showthread.php?t=197888

And below is something Koba placed in Rich's no45 thread which I found awesomely helpful as it has the spring rates as well.



Here is some of that rear shock stuff I was talking about.
It may not be 100% correct but can give a good idea for a starting point. I'm gradually getting more info.
My Spreadsheet tells me where the data comes from by different colours but I'm not going to get that complex here.
A lot of it is from the racetech website.

"Type" (e/e or e/f) means eye/eye or eye/fork (clevis).


<tbody>
Model
Year
Type
Length
Springrate (kg/mm)


NSR
MC18

MC21

MC22
e/e





285*

300

300
9.85


R6
1999-2002
e/e
305
9.3



2003/04
e/e

9.85




<tbody>
2005

</tbody>


<tbody>
e/e

</tbody>


<tbody>
295

</tbody>


<tbody>
10.8

</tbody>





<tbody>
2006/07

</tbody>


<tbody>
e/f Some 2007 e/e

</tbody>


<tbody>
290

</tbody>


<tbody>
9.8

</tbody>





<tbody>
2008/11

</tbody>


<tbody>
e/e

</tbody>



<tbody>
9.8

</tbody>




<tbody>
R1

</tbody>


<tbody>
2003

</tbody>


<tbody>
e/e

</tbody>



<tbody>
8.8

</tbody>




<tbody>
GSXR600

</tbody>


<tbody>
1992/93

</tbody>




<tbody>
6.2

</tbody>





<tbody>
1997

</tbody>




<tbody>
6.4

</tbody>





<tbody>
1998-2000

</tbody>




<tbody>
6.4

</tbody>





<tbody>
2001-2003

</tbody>


<tbody>
e/f

</tbody>



<tbody>
8

</tbody>





<tbody>
2004/05

</tbody>


<tbody>
e/f

</tbody>



<tbody>
7.6

</tbody>





<tbody>
2006-2009

</tbody>


<tbody>
e/f

</tbody>



<tbody>
9.4

</tbody>





<tbody>
2011

</tbody>


<tbody>
e/e ?

</tbody>






<tbody>
GSXR750

</tbody>


<tbody>
2011/12

</tbody>


<tbody>
e/e ?

</tbody>




</tbody>

The only other useful contribution I can make at this stage is that the cbr250 mc22 is 285mm eye to eye, has eye/fork mounts and has a spring rate of about 7.6 (?thats if I remember correctly, will have to confirm later)

[ac3_snow]

Also can anyone comment on ride height changes for a rear shock, as I understand a greater ride height (longer shock) puts more weight on the front and gives faster turn in (as this would also change the rake of the front). I feel as though a 1" (25mm) increase would be acceptable but would 2"(50mm) be abit extreme?

[Bert]

Also can anyone comment on ride height changes for a rear shock, as I understand a greater ride height (longer shock) puts more weight on the front and gives faster turn in (as this would also change the rake of the front). I feel as though a 1" (25mm) increase would be acceptable but would 2"(50mm) be abit extreme?

what will be the changes to the rake and trail with a 50mm increase??? or more so what is it currently?
its a little hard to make comment without so figures to get ones head around the bigger issue.

there is some great free stuff (calculators etc) and some interesting reading articles on http://www.tonyfoale.com/ (as posted many times before)
most of which should be applicable...

[koba]

Also can anyone comment on ride height changes for a rear shock, as I understand a greater ride height (longer shock) puts more weight on the front and gives faster turn in (as this would also change the rake of the front). I feel as though a 1" (25mm) increase would be acceptable but would 2"(50mm) be abit extreme?

It's more about the rake/trail changes than the weight.

Play with raising and lowering the front to get an idea of how much effect changes have. Measure geometry and take notes.

Racetech website has some info on quite a lot of shocks/forks.

[koba]

Another interesting point worth noting: Rich used his iPhone level app to measure a selection of bikes in the pits, rake varied from mine at around 25 deg to Craig's at something like 19.

[quallman1234]

Another interesting point worth noting: Rich used his iPhone level app to measure a selection of bikes in the pits, rake varied from mine at around 25 deg to Craig's at something like 19.

Your's definitely does feel like 25 deg! I found it doesn't like initial turn in so much. But is very good mid-corner.
Played around with dropping the forks through anymore?

RS125R is stated at 23 deg. That would be at the standard setting of 13mm through the bars. I know in NZ almost no one runs that! As it is designed for sweeping long corners. In the manual it states you can run them up to 25mm through. I was running 18mm and was probably on the lesser side compared to everyone else. But then again my forks were mostly bottom out half the time!

Need to figure out a shock for the RS50. E/E probably not a great problem as i will need to create a mounting point anyway. You need a harder spring rate/dampening for a straight swingarm to frame connection, correct?

[Bert]

....

Need to figure out a shock for the RS50. E/E probably not a great problem as i will need to create a mounting point anyway. You need a harder spring rate/dampening for a straight swingarm to frame connection, correct?

think leverage; so yes and you will need to thing about oil weight as well.

[ac3_snow]

Another interesting point worth noting: Rich used his iPhone level app to measure a selection of bikes in the pits, rake varied from mine at around 25 deg to Craig's at something like 19.

Cool little app, got one myself last night. currently my bikes at 21deg, and by modeling a longer shock(chunk of wood under the rear wheel) it drops to about 19 - 19.5, but I could pull the tripple clamps up further towards the top of the forks to slacken it off if need be.

I like the look of the 04-05 gsxr600 shock as it has similar mounts and spring rate too mine, just don't know what valving would be like, no doubt way off. Got lots to think about and fiddle with in the mean time:scratch:

[F5 Dave]

I struggle to believe that app. Can someone check against a protractor based measurer? 19 deg is wicked super steep & I'd think you would have self steering mid corner (feels horrible) as well as cronic instability at that rate.


Anyway here's my grouchy comment; Think about what you are doing. you are talking about Holous bolous swapping shocks designed for 200kg bikes onto bucket race bikes weighing less than 1/2 the weight. Yes a 600 really does weigh 200kg when you put gas in it.

spring rates can vary a lot depending on leverage. But you are bound to end up with a shock that is terribly valved for a bucket & likely to pack down & spit you off over the bumps. Hope your race track is smooth. Oh right.

At a min you will need a revalve by someone that knows what they are doing. Too stiff a spring will be a bad thing too. There have been threads on measuring rates using a press, ruler & scales, but you have to be careful, energy in springs came be returned quickly.

[quallman1234]

I struggle to believe that app. Can someone check against a protractor based measurer? 19 deg is wicked super steep & I'd think you would have self steering mid corner (feels horrible) as well as cronic instability at that rate.


Anyway here's my grouchy comment; Think about what you are doing. you are talking about Holous bolous swapping shocks designed for 200kg bikes onto bucket race bikes weighing less than 1/2 the weight. Yes a 600 really does weigh 200kg when you put gas in it.

spring rates can vary a lot depending on leverage. But you are bound to end up with a shock that is terribly valved for a bucket & likely to pack down & spit you off over the bumps. Hope your race track is smooth. Oh right.

At a min you will need a revalve by someone that knows what they are doing. Too stiff a spring will be a bad thing too. There have been threads on measuring rates using a press, ruler & scales, but you have to be careful, energy in springs came be returned quickly.

100% Agreed! Although 250 2 stroker shocks are not terribly far off, being naturally soft standard and weighing in about 160kg, if not lighter.
I might just try save my old RS50 shock. I hope i have all the parts still

[ac3_snow]

I struggle to believe that app. Can someone check against a protractor based measurer? 19 deg is wicked super steep & I'd think you would have self steering mid corner (feels horrible) as well as cronic instability at that rate.


Anyway here's my grouchy comment; Think about what you are doing. you are talking about Holous bolous swapping shocks designed for 200kg bikes onto bucket race bikes weighing less than 1/2 the weight. Yes a 600 really does weigh 200kg when you put gas in it.


Will check it against a protractor and let you know, think I'm fairly happy with the 21 (ish) deg it is at now.

I'm not to sure about the valving issue's all fairly new to me, I had a good read of some info rob taylor has provided and kind of getting my head around the front suspension workings. http://www.kiwibiker.co.nz/forums/showthread.php/138637-Damper-rod-forks-emulators-intminators-and-progressive-springs

My only thoughts regarding something like a six hundred shock maybe working was the difference in linkage ratio's. My very simplistic theory was that if the spring rates where the same then the difference in linkage systems between the two bikes would mean that the movement on the swing arm would have a very different effects, which would maybe allow for a similar shock between two different weight bikes.
But after your comment Dave I imagine that the valving inside the shock would also have an effect on the spring rate used...
so perhaps I am heading in the wrong direction, but thats all good it's why I asked for opinions and experiences.

[richban]

Are you measuring these angle's when you are on the bike coz thats when it really counts. Ideally they should not change much. My old FXR was 24 degrees and it went around corners great. New bike is now looking like it will be at 22.6 when i am on it. Still need to sort the sag proper, but lots of adjustment there. Thing is it all has to be correct, spring rates, sag settings and then you can worry about rake. I think is much more important to get the springs and sag working. Say your rear spring is to soft. Rake might be fine when the bike is sitting in the pits but when you are riding it it could be 4 degrees different and you wonder why you keep loosing the front.

[F5 Dave]

Confusingly some very different bikes have similar spring rates. This can be to do with leverage & suspension travel. But it can also do to do with the curve of the linkage. On a roadbike this may be set to have a very progressive ride in an attempt to make pot holes more comfortable yet still not bottom out while travelling at a clip with a chunky passenger. Either way it gets cloudy as progression has to do with shock travel but the issue we are mainly concerned with it 'shaft speed' & a linkage can't help through the curve if the damping is too stiff the shock will effectively treacle at that spot too long.

Fish for example chaged to a 600 shock but it had to be radically revalved.

[jasonu]

What about an RS125 NX4 piggyback shock? I might be able to conger up a couple of them. Will be in the NZ$320 (delivered to NZ) range give or take.

[richban]

What about an RS125 NX4 piggyback shock? I might be able to conger up a couple of them. Will be in the NZ$320 (delivered to NZ) range give or take.

50ish mm stroke on them. Good for my NSR. But would still need 300 spent to re valve and service. Also customs are getting really pissy about bringing in gas charged item's like shocks.

[koba]

Your's definitely does feel like 25 deg! I found it doesn't like initial turn in so much. But is very good mid-corner.
Played around with dropping the forks through anymore?


Yep, tried her from lowest to highest, current spot seems to work best as the bike is currently.

[jasonu]

50ish mm stroke on them. Good for my NSR. But would still need 300 spent to re valve and service. Also customs are getting really pissy about bringing in gas charged item's like shocks.

They didn't come my way anyway. However, in the next week or 2 there will be some NX4 chassis and motor stuff available. PM if there is anything you need and I may be able to get it for you.

[F5 Dave]

yeah market an NX4 engine in a production roadbike & sell me that so I can sleeve it.:rolleyes:

[jasonu]

yeah market an NX4 engine in a production roadbike & sell me that so I can sleeve it.:rolleyes:

HHHHmmmmmmmmmmmm:msn-wink: