Spring calculation help for a loveable fat man

[Michael]

I think I need to replace my springs to compensate my weight. I've researched this forum and have read mixed reviews about the RaceTech.com spring calculator.

I'm a heavier rider -- about 250 pounds. I also enjoy curvy roads and twisty-filled road trips. I'm doing well losing a bit of weight, and as my weight goes down, the more I enjoy more aggressive riding.

So here is a link to the calculator I was talking about:
http://old.racetech.com/evalving/SpringRateCalculation/dirtspring.asp?brand=Ducati&yr=95-99&ml=900%20Monster&formuse=form1&SpringType=Fork

Here is what I am considering for my 1996 m900.

Front:
FRSP S3534095    RT FRK SPR 34.7x340mm .95kg    $109.99        

Rear:
SRSP S5818085    RT SHK SPR 58.2x178mm 8.5kg    $109.99

Any thoughts?

Do you think an 8.9 would be better for the rear, or am I way off altogether?

That's me in front, on the way to Prescott, AZ last month

[Speeddog]

I'd say 1.0 springs for the front, and an 11.5 for the rear.

RaceTech calculator is wrong for rear suspensions on Monsters.

[ducpainter]

If it's an ST framed monster I think the rear would be even stiffer. Like a 12.5...8.5 isn't stiff enough.

Check with gage. He has an S4 and weighs about the same.

[Speeddog]

'96 M900, so a hoop-style rear.

Those seem to go about 1.0 lighter than the ST framed bikes.

[ducpainter]

'96 M900, so a hoop-style rear.

Those seem to go about 1.0 lighter than the ST framed bikes.

Doh...

I missed that.

Speeddog is probably right.

I have the same bike and I run a 10.0 at 180 lbs.

[Michael]

You guys are awesome! 

So ...
-- 1.0 for the front
-- 11.5 for the rear

Is there a specific brand or distributor or online store that you guys recommend?

Here are some more pictures of my fat butt for your enjoyment.



I put in a brand new back insert that isn't quite broken in yet.

[ducpainter]

I have race-tech front and Ohlins rear

[scott_araujo]

I weigh about 220# without gear.  I recently put in .95 RaceTech springs and 5w oil in my fork on an '03 800 Monster Dark.  The site did not list springs for my bike but I gave them dimensions and they got me springs that fit.  For my weight and 'aggressive street' riding style it listed .95 for the m900, .90 for the m750 (the two closest bikes). 

I went with .95 and after riding for a while it feels a little stiff to me, even with the sag set correctly.  Looking back, the m900 weighs a bit more and the m750 is closer to the weight of my bike.  I probably should have gotten the .90 springs, I may switch them at some point.

I would recommend RaceTech springs.  From what I've read, RaceTech measures their spring rates before labelling.  Some other manufacturers don't and people have gotten springs that are softer than labelled.  I've also read that someone got springs from RaceTech, needed one more notch up or down on the spring rate after installation, and was given full credit when they returned the originals in good shape.  YMMV. 

It's a very personal thing but I'm tempted to tell you to consider .95.  No matter what you do for the front it will be better.  The stockers are really weak and the progressive nature doesn't help.  For only $135 in springs and oil it's amazing the difference it made.

Can't help with the rear, haven't swapped that yet. 

Scott

[Speeddog]

RaceTech has the springs.

Give me a call if you like, there are some other options. 

[Michael]

I think I'll just get both front and back springs from RaceTech.

For the rear, though, do I just need to get a spring and adjust the preload and that's it -- I don't need to get or do anything else?

I mean, the front needs new fork oil and seals, along with the springs, but aside from having all the right tools, the back seems pretty straight forward.

[ducpainter]

I think I'll just get both front and back springs from RaceTech.

For the rear, though, do I just need to get a spring and adjust the preload and that's it -- I don't need to get or do anything else?

I mean, the front needs new fork oil and seals, along with the springs, but aside from having all the right tools, the back seems pretty straight forward.

The back is easy. You don't even need a spring compressor on a 96.

You don't need to change seals and oil in the front if there is no leaking. If you want to change oil weight that's fine, but if the seals aren't leaking leave them alone.

[Michael]

Thank you so much for the advice and help.

The left fork is leaking a little, so I figured it would be good to switch out the seals on both forks.

What weight oil do you recommend for the forks?

I live in Arizona where the temperature never gets near freezing (if that matters).

[ducpainter]

I think I have US 2 (racetech) in mine. My forks also have racetech gold valves

If you're not revalving that may be too heavy. The 96 Monster, and IMO, all non adjustable Monster forks are under sprung and over damped. Some folks use 5w oil which I believe is US 1 with stock valves.

Are you doing the work yourself?

[Michael]

Are you doing the work yourself?

I want to.

With any luck I'll recruit the help of some ducati-savvy friends.

[Michael]

Just got off the phone with RaceTech.

I ordered the 11.6 kg rear spring.
SRSP S5818116    RT SHK SPR 58.2x178mm 11.6kg    $109.99

I'm going to do the front later, but I need the rear right away.

The one odd thing is that the spring is blue instead of OEM yellow. I kind of liked the yellow, but hopefully blue will look cool, too.