Capt_Zoom
Raider Rider/xs newbie
How much sag/drop do you get in your front end when you sit on the bike?
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Fork sag
- Thread starter Capt_Zoom
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- suspension
jd750ace
Front Toward Enemy
Depends on your springs sir. Ideally, you will only consume 30-40% of your full travel. If it goes farther, more preload is needed, or your springs are shot. Springs are best set up to each rider's weight, front and back, to optimise suspension performance. Go to Race Tech's web site and read up a bit. Good site, good people, great products.
DirtyErnie
Renaissance Hick
Threads like this is why I cruise this forum. I didn't have any idea I wasn't running enough pre-load in the forks until I read JD's response.
My front end feels awesome now. THANKS!!!
My front end feels awesome now. THANKS!!!
jd750ace
Front Toward Enemy
No problem.
Capt_Zoom
Raider Rider/xs newbie
Really good information sources. Unfortunately I don't understand fork adjustments enough yet to use it all. I gotta go read the service manual and then check this out.
jd750ace
Front Toward Enemy
Zoom, put a zip tie around one of your tubes. lift the weight off the front till the forks top out. Have a helper slide the zip tie all the way down to the top of the dust seal. Set the weight of the bike on the forks as easy as possible, without over-travel. ease yourself onto the bike with your helper holding it upright. Dismount and unload the front again. Measure the distance the zip tie slid up, and that is your sag. Ideally, given the manual dimension of 5.9 inches for total travel, you want your static sag to be right about 2.5-2.6 inches. In order to maximize the benefit of the front working well, you have to get the back springs and preload nailed down as well, but we'll discuss that one after ya get some happy forks. You will appreciate the difference in handling.
If it does not drop enough,(less than 2.5 inches) you have too much preload, and need to shorten spacers, or if you have the adjustables, you can back off the top adjuster. If it goes down too far, you need a longer spacer, or use the adjuster if it's close.
If it does not drop enough,(less than 2.5 inches) you have too much preload, and need to shorten spacers, or if you have the adjustables, you can back off the top adjuster. If it goes down too far, you need a longer spacer, or use the adjuster if it's close.
Capt_Zoom
Raider Rider/xs newbie
JD,
Thanks for the tip. I'll do that. That's about how much I'm sagging now from what I can tell. It just seemed like a lot to me. More than I had before I changed the top clamp and put in new fork seals and oil. I'll use a zip tie and double check later this week.
Thanks for the tip. I'll do that. That's about how much I'm sagging now from what I can tell. It just seemed like a lot to me. More than I had before I changed the top clamp and put in new fork seals and oil. I'll use a zip tie and double check later this week.
bergoff
XS650 Addict
My forks need a lot of attention. I can bottom out my forks just by pushing hard with the front brake locked. Thanks for posting these tips.
jd750ace
Front Toward Enemy
I'd start with new springs if you can shove it down that easy. A lot of these older bikes have springs showing their age.
Another thing I reccomend is to use true fork oil and stay away from the ATF. Consistient damping over the life of the oil depends on the oil keeping it's original viscocity, or staying "in grade", as it's called. 7 to 10 weight seems to be the consensus, but generally speaking lighter oil delivers faster damping, which is desireable to most riders, as it keeps the tire in contact with the road better. But, if the damping is too fast (lighter oil), the tire can bounce up too hard on sharp bumps and at best, it kind or ratchets down, and you get chatter, at worst, you do it leaned over and loose traction. I would use either 7 or 10w. Should work fine for 95% of riders, as long as you don't add emulators, in which csa you should go with reccomendations. I do not have experience witm Mikes, but Race Tech as stated above, is a fantastic resource, even if you are not using thier stuff.
Capt_Zoom
Raider Rider/xs newbie
So with my 200lbs it drops 1.75 inches. I'm thinking with the wife it'll be around 1.5 (her bike) maybe less. So how do you adjust preload...is it that screw on the inside of the top nut of the forks?
I'd love for the bike to actually ride a bit higher in front. Right now I'm not getting the lean I want on the kickstand and can't shorten it anymore. Going to have to start bending it.
I'd love for the bike to actually ride a bit higher in front. Right now I'm not getting the lean I want on the kickstand and can't shorten it anymore. Going to have to start bending it.
jd750ace
Front Toward Enemy
The internal adjusting screw will raise your preload, but that might not be where your issue is. If it is compressing that hard under a cornering load, you might be under-sprung. Stock springs were .7kg-MM rate. At your weight, you probably need to be around a .85kg-mm, but that's just a guess. If you have new springs, What type are they, and what rate?
What fluid are you running?
The more info you can give me, the more I can help.
Your wife's bike seems to be sprung a little on the stiff side, if she has less than 2" of static sag. Let me know what you have in each set, and we can get you tuned up.
Check the pre-load by turning them counter-clockwise and counting the turns, or portions of a turn, until they top out.
Let me know what you have.
Also, dragging the stand could have more to do with the rear than the front. Let's work through 1 end at a time, and we'll get it doing all it can for you.
What fluid are you running?
The more info you can give me, the more I can help.
Your wife's bike seems to be sprung a little on the stiff side, if she has less than 2" of static sag. Let me know what you have in each set, and we can get you tuned up.
Check the pre-load by turning them counter-clockwise and counting the turns, or portions of a turn, until they top out.
Let me know what you have.
Also, dragging the stand could have more to do with the rear than the front. Let's work through 1 end at a time, and we'll get it doing all it can for you.
On the stock adjustable caps, they have three positions. You presss down and turn right to lock into the next tighter spot. Push down and turn left loosens the adjuster.
jd you measure a bit differently than I do for sag. My first measurement is with the bike upright, no rider, measure from the top of fork lower to bottom of tree.
Then as you say have rider carefully mount the bike. Measure again from lower to tree, the difference is sag. Measured this way, about 35 mm wil give a cushy ride and handling, 25 mm gives a firmer ride and handling.
On the rear I measure from top shock mount bolt to lower shock mount bolt.
The sag should match front to back.
With a zip tie on the fork, leave it on the fork, start with it pushed down, after a normal ride. A 1/2 hour or more, doing some hard cornering and braking, rough roads the zip tie should end up about half way between the fork lower and tree.
If it is much lower then you have a bit much preload or to heavy an oil. The opposite if to high.
The Race Tech site has a lot of good info. Googling motorcycle suspension tuning will lead you to many good sites with lots of info.
As far as oil, a good fork oil is ok but AFT works just fine, The weight is about 10w and being for a transmission it has seal preservers in it as well as anti-foaming agents. All good things for forks.
Expermenting with several oils isn't to costly and you can tune the damping some what.
I have a set of the later 35 mm forks with adjustable caps. I did the Minton Mods to the dampers, didn't add holes just drilled out the four I had. I replaced the springs with a set for an early Harley 35 mm Showa fork. They are made from heavier wire, a bit longer. Can't recall the exact specs, got them wrote down some where.
With the adjustable caps on the lightest setting I get about 25 mm sag. With aft they work well, firm but not harsh.
Leo
jd you measure a bit differently than I do for sag. My first measurement is with the bike upright, no rider, measure from the top of fork lower to bottom of tree.
Then as you say have rider carefully mount the bike. Measure again from lower to tree, the difference is sag. Measured this way, about 35 mm wil give a cushy ride and handling, 25 mm gives a firmer ride and handling.
On the rear I measure from top shock mount bolt to lower shock mount bolt.
The sag should match front to back.
With a zip tie on the fork, leave it on the fork, start with it pushed down, after a normal ride. A 1/2 hour or more, doing some hard cornering and braking, rough roads the zip tie should end up about half way between the fork lower and tree.
If it is much lower then you have a bit much preload or to heavy an oil. The opposite if to high.
The Race Tech site has a lot of good info. Googling motorcycle suspension tuning will lead you to many good sites with lots of info.
As far as oil, a good fork oil is ok but AFT works just fine, The weight is about 10w and being for a transmission it has seal preservers in it as well as anti-foaming agents. All good things for forks.
Expermenting with several oils isn't to costly and you can tune the damping some what.
I have a set of the later 35 mm forks with adjustable caps. I did the Minton Mods to the dampers, didn't add holes just drilled out the four I had. I replaced the springs with a set for an early Harley 35 mm Showa fork. They are made from heavier wire, a bit longer. Can't recall the exact specs, got them wrote down some where.
With the adjustable caps on the lightest setting I get about 25 mm sag. With aft they work well, firm but not harsh.
Leo
jd750ace
Front Toward Enemy
I have used the weighted Vs empty sag technique you speak of before. It works quite well. I have found that with most bikes, the full travel to laden method works about as well, although it is more commonly used with a progressive rate spring. I could not remember if the preload adjusters went 3 or 4 position, and I think they are 10MM apart, if I remember that part correctly. If you have the proper rate spring for your weight, that should be plenty of room.
I'll have to google the Minton Mods. Sounds like it's to speed up the damping a bit.
Also, if you want to firm up a bit against front end dive under braking, raising the oil level helps with this by reducing the "free" compression time before the damping slows the rate down. Can make it a little bit harsh over smaller bumps for some, but if it was an infinitely adjustable suspension, it would be different.
I was holding up on the advise for the rear until I got him comfy on the front, but as you said, laden sag front and rear, and spring rates front and rear, should match, such that the bike squats straight down about 1"-1'25" with the rider in position.
Thanks for chiming in. Now I'm gonna look up them spring rates and the Minton mods!
I'll have to google the Minton Mods. Sounds like it's to speed up the damping a bit.
Also, if you want to firm up a bit against front end dive under braking, raising the oil level helps with this by reducing the "free" compression time before the damping slows the rate down. Can make it a little bit harsh over smaller bumps for some, but if it was an infinitely adjustable suspension, it would be different.
I was holding up on the advise for the rear until I got him comfy on the front, but as you said, laden sag front and rear, and spring rates front and rear, should match, such that the bike squats straight down about 1"-1'25" with the rider in position.
Thanks for chiming in. Now I'm gonna look up them spring rates and the Minton mods!
I also reccomend using the 6 inches down method for oil level. This give it more of the air shock effect than the stock specs. On most of the later forks that's an increase of about an ounce and a half more oil. This works well for me.
Minton Mods, go to 650central, scroll down the list on the left. They are there.
Leo
Minton Mods, go to 650central, scroll down the list on the left. They are there.
Leo
jd750ace
Front Toward Enemy
Thanks. 650 Central is in my bookmark pile!
Capt_Zoom
Raider Rider/xs newbie
I'm sure these are the stock springs. My wife, who will primarily be riding the bike weighs between 125-140 geared up.
Would something like the progressive springs be beneficial for someone who is as light as her?
The backs are going to be a little stiff. They are the burly slammers meant for 2003 sportsters. Not a lot of travel back there due to the design.
Would something like the progressive springs be beneficial for someone who is as light as her?
The backs are going to be a little stiff. They are the burly slammers meant for 2003 sportsters. Not a lot of travel back there due to the design.
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jd750ace
Front Toward Enemy
A lot of people like the progressive springs. They generally provide a more plush short travel than a straight rate spring. I personally can live with a little bit of feedback at slower paces, as long as I get the consistient feel I want under moderate to heavy braking, and spirited cornering. I don't like the front to feel like it's trying to squirm out from under the center of pressure, if you know what I mean. I ride the front harder than most people, and I'm in the upper percentile where mass is concerned, at 245 or so. For the simple fact that I do ride the front so hard, I'm a big fan of straight rate springs and cartridge emulators. Fresh oil, serviced correctly and progressive springs seem to make the overwhelming majority of people happy, on most bikes.
On straight rate springs, the stock springs, assuming they are good, and judging by the number you posted earlier for laden sag, may be a bit strong for her size, in which case I would think the progressives would be a good choice.
Leo, I went and checked out the Minton Mods. Good stuff! Thanks!
On straight rate springs, the stock springs, assuming they are good, and judging by the number you posted earlier for laden sag, may be a bit strong for her size, in which case I would think the progressives would be a good choice.
Leo, I went and checked out the Minton Mods. Good stuff! Thanks!
The stock springs are a dual rate progressive. They're rated at about 27 lb/in for the 1st 4", 36.4 lb/in for the last 2". If you need something softer, you might try stock SR500 springs, they're rated at 22.4/28. With no fender or brace on the front, you're going to have major fork flex problems so spring choice probably doesn't matter much. Adding to the problem will be that stiff rear suspension. That can transfer to the front as a wobble. She'll be too busy hanging on for dear life to worry about the ride quality, lol.
jd750ace
Front Toward Enemy
Ya gotta give both ends equal attention for a balanced ride, that's for sure!
When the rear is too stiff, suspension "non-travel" converts into leverage on the front varying the pressure on the tire and front suspension. That, combined with the accompanying occilation of the rake and trail geometry, equals wobble.
If you want to ride a wild one, try a rear monoshock with blown damping! full time job just holding a line!
When the rear is too stiff, suspension "non-travel" converts into leverage on the front varying the pressure on the tire and front suspension. That, combined with the accompanying occilation of the rake and trail geometry, equals wobble.
If you want to ride a wild one, try a rear monoshock with blown damping! full time job just holding a line!
