Rear sag on 2000 R1100RT

[k7gle]

I understand I should set "race" (fully loaded) sag at about 30% of full spring travel, which is pretty straightforward on a standard two-shock system where I could measure the distance parallel to the spring travel.

The specs for the R11RT list max spring travel at 135mm. With paralever suspension the sag measured vertically between the rear axle and a point on the suspended frame doesn't necessarily have anything to do with the amount of compression of the spring due to the geometry of the system.

So how should I choose a sag setting?

Thanks

- Glenn

 

[bc1100s]

Welcome to the forum!

You're looking for a percentage of your total wheel travel, not spring travel. 30% is a good place to start.

Measure from your axle to a fixed point directly above it. Adjust preload as required.

 

[k7gle]

Thanks, but my question is, "30% of what?"

The BMW spec for rear suspension is the same dimension, but stated different ways in different sources:

"Travel / dimension = 5.31 inches"
"Suspension travel = 5.31 inch"
"Spring travel / Rear 135mm"

If this means "suspension travel" I'm good - 5.31"/135mm is my denominator.

If it really means "spring travel" I'm in trouble, as the spring travel is almost certain to be different from the suspension travel because of where it's located.

John Casebeer, proprietor of Motool, which makes the excellent Slacker digital sag gauge (featured in the current version of Motorcycle Consumer News), tracked this down for me and told me this a.m. that he is of the opinion that this spec actually does mean "suspension travel." I'll just go forward on that assumption and see if it feels right.

- Glenn

PS - the articles on this site and others led me to refill the preload adjuster over the weekend...the adjuster gets very firm now (indicating it's actually working) after about 2 clicks, compared to needing to be cranked down almost 50% of its travel before giving any resistance.

- G

 

[bc1100s]

"You're looking for a percentage of your total wheel travel, not spring travel. 30% is a good place to start."

Hopefully that's more clear. Looks like 5.3" Call it 135mm. Sag should be around 40mm. Start there and adjust to taste.

 

[k7gle]

Thanks. I understand that's what I'm trying to measure against...my confusion was around whether the 135mm dimension given was wheel travel or spring deflection - the wording of the specs I found were ambiguous.

 

[darrell]

Refilling Preload Adjuster Question

Thanks, but my question is, "30% of what?"

The BMW spec for rear suspension is the same dimension, but stated different ways in different sources:

"Travel / dimension = 5.31 inches"
"Suspension travel = 5.31 inch"
"Spring travel / Rear 135mm"

If this means "suspension travel" I'm good - 5.31"/135mm is my denominator.

If it really means "spring travel" I'm in trouble, as the spring travel is almost certain to be different from the suspension travel because of where it's located.

John Casebeer, proprietor of Motool, which makes the excellent Slacker digital sag gauge (featured in the current version of Motorcycle Consumer News), tracked this down for me and told me this a.m. that he is of the opinion that this spec actually does mean "suspension travel." I'll just go forward on that assumption and see if it feels right.

- Glenn

PS - the articles on this site and others led me to refill the preload adjuster over the weekend...the adjuster gets very firm now (indicating it's actually working) after about 2 clicks, compared to needing to be cranked down almost 50% of its travel before giving any resistance.

- G

What do you mean by this and how did you do this?

 

[m_stock10506]

https://www.youtube.com/watch?v=oN26VaJuZhE

Video showing refill of the preload adjuster.

Basic steps are:
Bike on center stand (no load on rear wheel)
Turn adjuster completely "off" - counter clockwise
Remove Adjuster from frame, turn upside down. Note orientation of the hose.
Remove hose, tie up so it doesn't lose oil
Push adjuster piston all the way down
Fill adjuster with "Jack Oil"
Reinstall hose with banjo bolt and washers. Make sure it is oriented as previously.
Attach adjuster back on the frame.
Adjuster should now engage at 1st or 2nd click.

 

[darrell]

https://www.youtube.com/watch?v=oN26VaJuZhE

Video showing refill of the preload adjuster.

Basic steps are:
Bike on center stand (no load on rear wheel)
Turn adjuster completely "off" - counter clockwise
Remove Adjuster from frame, turn upside down. Note orientation of the hose.
Remove hose, tie up so it doesn't lose oil
Push adjuster piston all the way down
Fill adjuster with "Jack Oil"
Reinstall hose with banjo bolt and washers. Make sure it is oriented as previously.
Attach adjuster back on the frame.
Adjuster should now engage at 1st or 2nd click.

Appreciate the response. My new to me Seatao has to be turned 50% of the way before it engages so hopefully this will take care of that.

 

[darrell]

Refilling Preload Adjuster Worked as You Described

https://www.youtube.com/watch?v=oN26VaJuZhE

Video showing refill of the preload adjuster.

Basic steps are:
Bike on center stand (no load on rear wheel)
Turn adjuster completely "off" - counter clockwise
Remove Adjuster from frame, turn upside down. Note orientation of the hose.
Remove hose, tie up so it doesn't lose oil
Push adjuster piston all the way down
Fill adjuster with "Jack Oil"
Reinstall hose with banjo bolt and washers. Make sure it is oriented as previously.
Attach adjuster back on the frame.
Adjuster should now engage at 1st or 2nd click.

It worked exactly as you described. Took 15 minutes. Hardest part was getting the oil in as need to evacuate air as oil is added. Used a small medical syringe adding 9 mls of jack oil and now it has contact at click 3 instead of number 20 of the 40 clicks total on the G650GS Seatao. Thanks.