# setting up my bike, what do these numbers mean?

23 replies to this topic
• # peezy

Posted 06 May 2012 - 04:06 PM

So my last trip to the desert my bike was riding like crap, kept bouncing around in the whoops and just little bumps making it bounce like it was a jump. My friend thinks i need oil in my shock etc. When the bike is on the ground, i can move the back of the bike up and down pretty easy.

I took some numbers for the sag, here they are.

R1*bike on stand =24 3/4in = 628.65mm
R3*bike on ground, no rider = 24 5/8in = 625.48mm
R2*bike on ground, with rider = 21 3/4in = 552.45mm

Note: I was standing on the bike instead of sitting, is there a big difference?

Note: I am 5' 9" tall and about 160lbs

So, from those numbers i understand you do R2-R1=Race Sag and R3-R1=Static Sag correct? So with these numbers do i need a new spring what do i need to do to make it more set up to me. Oil weight, springs, etc.

Also i measured my forks to.

F1*Bike on stand = 35 1/8in = 892.17mm
F2*Bike on ground, with rider = 34 1/4in = 869.95mm
F3*Bike on ground, no rider = 33 1/4in = 844.55mm

I do not know what to do with the fork numbers to figure out what i need?

So if anyone can help me set my bike up for me that would be great. I ride in so-cal area, plaster city desert so hard pack, sand, and i also ride track.

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• # 2strokeDude

Posted 06 May 2012 - 04:18 PM

Your supposed to be in the same position as you ride when you measure sag. something has to be screwed up with your numbers.  Your saying your bike sits lower on the ground with no rider compared to on the ground with a rider?

• # peezy

Posted 06 May 2012 - 04:51 PM

I think messed up the front fork numbers,

it should be

F3*bike on ground, no rider = 869.95mm
F2*bike on ground, with rider = 844.55mm.

i will re do the front forks tomorrow to double check, are you saying the rear numbers are wrong too?

i read somewhere you can messure them standing if you wanted to? whats better setting riding position or standing riding position?

Edited by peezy, 06 May 2012 - 04:52 PM.

• # crf150f guy

Posted 06 May 2012 - 04:57 PM

I think rear sag is supposed to be around 100mm so I believe you need a softer rear sping.  Im not so sure about the front though.  I cant remember the recommended sag for that one.

• # kan3

Posted 06 May 2012 - 05:05 PM

Your rear spring should be fine.  Go out on the preload collar until you get to 100mm with rider and do the 3 measurements again.

• # peezy

Posted 06 May 2012 - 05:05 PM

ok i will do it again tomorrow, i will set the rear to stock settings if it is not stock and let you guys know. So when you subtract r2 from r1 is it supposed to be a negative number?

Edited by peezy, 06 May 2012 - 05:07 PM.

• # kan3

Posted 06 May 2012 - 05:11 PM

No, it should be positive.  You use R3 to verify that you have the correct spring after everything is set.

• # peezy

Posted 06 May 2012 - 05:15 PM

then my numbers are way off? So i will set up everything to stock and take the numbers again tomorrow if i have time. This is a pain in the *** lol

• # 2strokeDude

Posted 07 May 2012 - 04:46 PM

peezy, on 06 May 2012 - 04:51 PM, said:

I think messed up the front fork numbers,

it should be

F3*bike on ground, no rider = 869.95mm
F2*bike on ground, with rider = 844.55mm.

i will re do the front forks tomorrow to double check, are you saying the rear numbers are wrong too?

i read somewhere you can messure them standing if you wanted to? whats better setting riding position or standing riding position?
I'm sorry my head was not in the right place yesterday.  Lets see if I can get this right tonight.  If I calculated correct your sag right now is 76.2.  You want a sag between 100-110 so you need to soften your preload until you get to at least 100.  After you get to the correct race sag you will want to check static sag.  Remeasure R3 and then subtract R1-R3.  This should fall in between 25-45mm.  Less than 25mm usually means a stiffer spring and more than 45mm usually means a softer spring.

• # peezy

Posted 17 May 2012 - 12:31 PM

Ok, sorry for reply so late. I have been busy. So when i soften my preload, i adjust the nut up instead of down to compress the spring correct?

Also if i don't want to spend so much money on re-doing my whole suspension, could i just re charge the rear shock, and change the oil in the forks?

Thanks for the help. I will post the numbers when i get home and adjust the race sag.

• # peezy

Posted 17 May 2012 - 07:13 PM

ok, i got my new numbers in, they look bad. well to me at least.

a=bike on stand
b=bike off stand, with rider
c=bike off stand, no rider

a= 635mm
b= 536.70mm
c= 622.3

so i figured my race sag is 98.3 and my static i am not to sure of yet. i think i got 12 but not sure.

My friend thinks my shock is blown, could it just might need a new spring? or maybe should i try re-charge it and go from there?

• # kan3

Posted 18 May 2012 - 04:57 AM

What's the condition of your shock and linkage bearings?  You gained 22mm of rider sag but only 9mm of static.

• # peezy

Posted 18 May 2012 - 06:59 AM

about 3 rides ago i re greased the linkage. the shock i am no to sure. my friend told me it is blown, witch i am not sure. but i can push down on the bike with my hands and it will go down pretty far. like there is not a lot of compression. should i get it re-charged?

• # arnego2

Posted 19 May 2012 - 05:06 AM

Sounds like a good idea

• # peezy

Posted 19 May 2012 - 09:42 AM

if i have rebuilt the engine before, do you think i can teach my self how to change the oil in the shock and forks doing it by my self, then just take the shock in for the charge? any good guides?

• # YHGEORGE

Posted 19 May 2012 - 11:00 AM

I do not mean this to be rude. Have a fellow rider with a lot of experience or who is a racer go thru the measurement process with you. Most guys you meet at the track or your riding area will be glad to help. Someone other than your buddy. I think you need to be sure of the EXACT measurement before you do something that is not necessary. And borrow or buy an OEM SERVICE manual.

• # peezy

Posted 19 May 2012 - 11:27 AM

Don't think you are being rude. I don't have anyone that can help. only local shops witch would most likely charge for it. I don't think the oil in the rear shock has never been replaced and its a 03 so almost ten years with the same oil. don't you think its time for new oil and new charge of nitrogen?  I will check with a few friends that do ride a lot and see what they think and if they will help.

• # YHGEORGE

Posted 19 May 2012 - 01:10 PM

Yes, it is ready for a service. I'll bet thats all it needs. Good luck.

Edited by YHGEORGE, 19 May 2012 - 01:10 PM.

• # peezy

Posted 20 May 2012 - 09:26 AM

thanks, can anyone show me to a good guide on how to change the oil on a rear shock?

• # MX Tuner

Posted 20 May 2012 - 10:36 AM

A fresh nitrogen charge isn't going to help a thing. There can be safety issues *learning* how to rebuild a shock, even with a manual. You tube videos are a joke.  Nobody was born knowing it but you need to have someone show you the correct way to do it with quality parts. The MSR, Moose, and All Balls replacement parts are marginal at best. there are plenty of readily available good quality replacement parts available on line and at local shops.

Finding someone who can show you may be your biggest hurdle. If you were local to here, I'd be glad to show you and I have all the normal rebuild parts in stock for 98% of the components out there made in the last two decades. I'd suggest not relying on your neighbor but someone who does it for a living.

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