So today I was at a charity ride and the RaceTech support van was there doing suspension setups. I've been dicking with mine for a while and it's never been quite right so I figure the $20 was worth it to have someone look at it.
My main complaint is that on the highway the concrete seams beat the crap out of me. So the guy got it all measured and adjusted the front. He starts working on the rear and calls me over. His diagnosis is that the rear is too low, so it's sitting back and feeling unbalanced. His suggestion is that I add two full turns of preload to the rear to raise it up and even the weight distribution from front to back.
I'm a little skeptical about fixing the suspension with that approach, but I wanted to poll you folks to see what you think. Would it be more beneficial to spring for the adjustable ride height rod or is cranking down the preload a good-enough solution?
Note: I ride 100% street, mostly 'touring' type rides. I do ride canyons, but not as much.
Thanks for your input.
Can you reduce the compression damping and/or fork oil height on your bike?
Seems to me that will reduce the jarring somewhat.
Do you not have an adjustable ride hight rod?
I'd get that first, if you don't have it already.
Quote from: DarkStaR on November 21, 2010, 05:15:05 PM
Do you not have an adjustable ride hight rod?
I'd get that first, if you don't have it already.
no, the 620's have a solid rod.
The 748 adjustable rod will bolt right up.
To me, that seems a little counter-intuitive. If you are complaining of a harsh ride, I don't see how making it stiffer would help. I can however understand rebalancing the bike. In my opinion though, I think it would be wiser to go for the adjustable ride height rod in order to maintain the correct spring characteristics.
There just isn't enough information here to answer your question. What year and model is your bike? Is the sag correct? Is the spring correct for your weight? Do you have an adjustable link? If so, is the base setting correct? You might want to visit Speeddog.
Quote from: howie on November 21, 2010, 08:02:04 PM
There just isn't enough information here to answer your question. What year and model is your bike? 2004 620 Is the sag correct? it is now. Is the spring correct for your weight? According to nick it is and when I gave the Race Tech guy the spring weights he agreed they're correct. Do you have an adjustable link? No. If so, is the base setting correct? You might want to visit Speeddog.
you're right. I left a lot to assumptions. see above.
I would say re check your sag and adjust preload as needed to get the rear up to proper height, then see how it feels. I don't see how this will help with those expansion joints, but the bike should handle better. If not happy, try backing off on compression a couple of clicks. Oh, how many miles on the shock oil? May be ready for a change. My experience is those expansion joints are pretty horrible in about anything but a Lincoln Town Car.
Properly set suspension is witchcraft
dont argue with those who understand it grasshoppa
adj rod is a good idea however
I'm no expert, but from experience it is damping that makes a ride harsh or plush, not the spring.
When my monster was stock any 'sharp' bump would rattle my teeth...expansion joints, manhole covers, etc. I had the springs changed front and rear and the forks re-valved. I also went with an Ohlins. The springs installed were stiffer at both ends.
The bike eats up expansion joints with no harshness now.
I don't think adding preload will solve your problem.
Quote from: Privateer on November 21, 2010, 05:27:32 PM
no, the 620's have a solid rod.
Actually the 140mph 620 Capirex's do have an adjustable rod. The standard 620's do not.
Quote from: Langanobob on November 22, 2010, 06:09:47 AM
Actually the 140mph 620 Capirex's do have an adjustable rod. The standard 620's do not.
thanks for the clarification.
as for an adjustable rod, I found this reasonably priced one on ebay
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=250728107581&ssPageName=ADME:X:RTQ:MOTORS:1123 (http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=250728107581&ssPageName=ADME:X:RTQ:MOTORS:1123)
I other ones I found didn't look like they were adjustable while on the bike. nor were they this nice looking. Motowheels had a really nice one, but at $340, out of my budget.
I wouldn't mind spending a little more to support a sponsor, but didn't find one in my searching their sites. Any suggestions other than the one above?
thanks.
The ebay listing is for a lowering link/rod. Not exactly what you need?
If it's true, as posted above, that a 748 rod is adjustable and will bolt on - keep looking for that.
If your Monster suspension gives you a harsh ride, the advice you got might help - despite the more normal raise-by-rod approach. Adding preload is often needed to get the right sag numbers, it's done to get the most out of what you've got. Remember that it will also raise the rear to a geometry where weight is moved forward, which might make the front suspension perform better (not bouncing quite as much).
So, first get the numbers as close as you can - then maybe add an adjustable rod if still needed.
I have learned enough about suspension to know that it is best to get professional help. If you can afford an hour work at a good suspension shop, you will not regret it.
Someone correct me if I'm wrong, but I though the SBK adj. rod was of a diffenent length!?! (lower or higher)?
A stock one from any of the bigger monsters will fit sans 696/796/1100, and thry ARE adjustable while installed...it's just not fun to adjust. Even with some of the fancier pieces, it's still a pain to get to the lock nuts on either end, but possible.
buy a 748 adjustable dogbone on ebay. way cheeper than the $300 one mentioned. most lowering links have enough adjustability to raise the rear because they are made for a varity of ducatis. for example mine is a ca cycles lowering one and was about $75 brand new. it has plenty of adjustability up and down. don't mickey mouse one they can brake and then your ass is in trouble, saw it at the track [bacon]
I use the one below on my M695 - has been worknig great for several years. I think it was about $75 from (?) eastern cycle. Their normal unit is for lowering, but this one was made to accomodate standard ride-height to + one inch. The beauty of new is that you can load up the threads with antisieze so next time you try to adjust it it's not frozen solid!
BK
(http://i34.tinypic.com/2dvu1d4.jpg)
thats the same one i have i think [bacon]
The 748 adjustable rod I'm running was sourced on ebay for $25. Matching the fixed-length original M800 rod was well within the adjustment of the 748 rod - only ~3/8" of threads showing at each end, with just a bit of extra height dialed in.
IMO, the amount of preload you'll have to add to the rear shock to get any appreciable additional ride height will severely compromise your setup and handling. Adjustable rods are made to adjust ride height, so that seems like the proper way to do it.
Quote from: stopintime on November 22, 2010, 07:40:38 AM
The ebay listing is for a lowering link/rod. Not exactly what you need?
I sent the guy a message and was informed it can be used to raise as well. I can read, I'm not a complete idiot.
Fixing ride height problems with pre-load isn't a good plan.
A longer pushrod changes the progression of the linkage.
I don't have the info here, but I'll try to check tomorrow.
But onto the original problem, harsh freeway ride is usually a high-speed damping issue.
Just to clarify, high shock movement speed, not high bike speed.
You could try reducing the compression damping with the adjust screw on the reservoir.
Unfortunately it's more of a slow speed adjustment, but it can help a bit.
Quote from: Speeddog on November 22, 2010, 10:49:51 PM
Fixing ride height problems with pre-load isn't a good plan.
A longer pushrod changes the progression of the linkage.
I don't have the info here, but I'll try to check tomorrow.
But onto the original problem, harsh freeway ride is usually a high-speed damping issue.
Just to clarify, high shock movement speed, not high bike speed.
You could try reducing the compression damping with the adjust screw on the reservoir.
Unfortunately it's more of a slow speed adjustment, but it can help a bit.
good info, thanks Nick.
On a plus side, the last two days I rode to work the ride was MUCH better. I need to sit down and figure out what he set everything at. There's a section of the 57N I ride almost every day that just beats the hell out of me. Coming home the last two days the bike was much smoother and manageable with only the worst parts really bouncing me around.
I also checked with CA Cycleworks because I couldn't find anything from them. They do have an adjustable link but out of my price range at $280. a beautiful piece but can't swing it right now.
(http://www.ca-cycleworks.com/shop/catalog/ducati/img/ag_902175.jpg)
I'll start looking on ebay (yuck) and see what I can find. Thanks for the tip on the 748 rod.
fork oil height won't have any direct relation with his issue, fork oil will play a major role when travels is @ it's last 1/3 of the stroke and more.....
do you have any idea how much preload you have on the front and rear to achieve your sag?
Quote from: battlecry on November 21, 2010, 03:51:41 PM
Can you reduce the compression damping and/or fork oil height on your bike?
Seems to me that will reduce the jarring somewhat.
Your comment may be relevant, or not, depending on how high those slab joints are. Around here, we soften up compression damping to reduce the bumps we get from the slab. The 620 does not have compression or preload adjustment on the forks. Raising rear height may be something he needed to do anyway, but it doesn't address his initial complaint.
Put zipties on the fork slider to indicate maximum fork compression on your slab rides and on your panic stops. If you are nowhere near full travel, you can start reducing the fork oil height in, say, 5mm increments until you soften it up and use more of your travel. Motion Pro makes a nice measuring syringe tool for the job.
You must keep enough fork oil to cover the damper assembly under the spring. If you are adventurous, you can try to experiment with (increase) the size of the holes at the lower end of the damper tube. You can look at what some of the SV folks have done for ideas. If you feel like spending some bucks, I'm pretty happy with AK20s and can recommend them. I still run them with zero compression "clicks" on some slab roads.
Good luck.
Quote from: battlecry on November 25, 2010, 12:12:02 PM
Your comment may be relevant, or not, depending on how high those slab joints are. Around here, we soften up compression damping to reduce the bumps we get from the slab. The 620 does not have compression or preload adjustment on the forks. Raising rear height may be something he needed to do anyway, but it doesn't address his initial complaint.
Put zipties on the fork slider to indicate maximum fork compression on your slab rides and on your panic stops. If you are nowhere near full travel, you can start reducing the fork oil height in, say, 5mm increments until you soften it up and use more of your travel. Motion Pro makes a nice measuring syringe tool for the job.
You must keep enough fork oil to cover the damper assembly under the spring. If you are adventurous, you can try to experiment with (increase) the size of the holes at the lower end of the damper tube. You can look at what some of the SV folks have done for ideas. If you feel like spending some bucks, I'm pretty happy with AK20s and can recommend them. I still run them with zero compression "clicks" on some slab roads.
Good luck.
I didn't anticpate this thread going this direction which is why I didn't add much info.
For the record, while I do ride a 620, it has S2R1000 forks and a S4 shock, both with comp/rebound adjustments.
When I get some time, I'll measure up my sag and get all the adjustment points documented. I did have them all down but the Race Tech guy didn't document anything so I didn't ask.
OK. Measured the rear today.
Static sag, 30mm
Free sag, 4mm
I have about 7mm of thread showing above the preload adjuster.
finding a suspension guy and getting him to stand behind the work he does with you is key if you want to make steps into strides. find a shop/suspension guy you trust and invest the time and money. once you find the spot that you want you'll be in astonishment that you didn't just do it before like that. it also makes the next bike that you own easiser to set up because you have a better idea to know where to start. my 2 cents [bacon]
Quote from: humorless dp on November 22, 2010, 04:50:19 AM
I'm no expert, but from experience it is damping that makes a ride harsh or plush, not the spring.
When my monster was stock any 'sharp' bump would rattle my teeth...expansion joints, manhole covers, etc. I had the springs changed front and rear and the forks re-valved. I also went with an Ohlins. The springs installed were stiffer at both ends.
The bike eats up expansion joints with no harshness now.
I don't think adding preload will solve your problem.
With suspension, balance is the key. Everything interacts. Spring rate, compression/rebound, pre-load, ride height. Something as insignificant as the difference in ride height between a 180/55 and a 190/50 tire can affect it, I've experienced it personally.
As for expansion joints, the ones around here are affected by something as insignificant as tire pressures. ;D
Quote from: Privateer on November 28, 2010, 05:10:54 PM
OK. Measured the rear today.
Static sag, 30mm
Free sag, 4mm
I have about 7mm of thread showing above the preload adjuster.
Those numbers are fine AFAIK.
Plan on measuring the front? (reg balance as commented)
Quote from: atomic410 on November 30, 2010, 02:45:19 PM
finding a suspension guy and getting him to stand behind the work he does with you is key if you want to make steps into strides. find a shop/suspension guy you trust and invest the time and money. once you find the spot that you want you'll be in astonishment that you didn't just do it before like that. it also makes the next bike that you own easiser to set up because you have a better idea to know where to start. my 2 cents [bacon]
+1 on that. Over the course of several years I learned everything I could and experimented with the entire gamut of parameters, including fork oil viscosity and height, sags, ohlins, penske, matris, 4-5 different shock springs, geometry, etc. I approached everything very systematically. It was quite a journey and I learned plenty. Recently I took it to the local guru and $20 later the bike was "balanced" in a manner that I could never quite achieve on my own. I was trying to do things by the book, which is all I knew, but the guru could draw on his many years of experience to get everything to a happier place with some final tweaking of spring tension and hydraulics. The same guru/tuner, Dave Moss, does the trackside tuning on my SBK. Great local resource. A suspension that works for you is a wonderful thing, but at the same time any given setup is always a compromise!
BK
yeah, i paid the $20 and it feels great (well, as good as it can be). I was only questioning the "increase preload to raise ride height and balance out the front/back."
It seemed counter intuitive to me to use preload to raise the ride height when really I should use an adjustable ride height rod to raise the rear to get the same result without compromising the preload settings.
He wanted to do it himself but it's a pain in the ass to get to the adjusters because of my rear shocks reservoir.
Then I don't get it. It feels great, but you don't trust your tuner? Maybe you should find a new tuner that you trust? Sometimes tweaks need to be made that might seem counter-intuitive, but it sounds like the guy was simply trying to make the best of the current setup before recommending new parts. An adjustable rod is a good investment and every monster should have one, especially if you've already gone to the trouble of replacement forks/shock.
BK
Quote from: Privateer on December 02, 2010, 07:01:26 PM
.......... I was only questioning the "increase preload to raise ride height and balance out the front/back."
............
With the numbers you've got now, I'd say it's a bad idea to increase preload.
If, on the other hand, your sag was much deeper - then fixing that would also raise your ride height.
Maybe that's what he was thinking....
Quote from: battlecry on November 25, 2010, 12:12:02 PM
Your comment may be relevant, or not, depending on how high those slab joints are. Around here, we soften up compression damping to reduce the bumps we get from the slab. The 620 does not have compression or preload adjustment on the forks. Raising rear height may be something he needed to do anyway, but it doesn't address his initial complaint.
You're mixing two different things, compression damping and air spring, the two of them have different roles on an hydraulic system.
Those "slabs around there" will have to be as big as a motocross track woops in order for the oil level to play a role in that ecuation.
Anyways, I'm in LA area, that's my "around here", the 405 "king of slab joints area....."
Quote from: Privateer on November 28, 2010, 05:10:54 PM
OK. Measured the rear today.
Static sag, 30mm
Free sag, 4mm
I have about 7mm of thread showing above the preload adjuster.
you mean 30mm rider's sag and 4mm static.....
how much preload you have (amount of mm the spring is compressed, if the free length is 120 mm and it measures 100 installed then you'll have 20mm preload)
I usually start @ 10mm static and 30mm rider, by those numbers IMMO your spring is weak since if you reduce preload to achieve 10mm static your riders will be around 35mm, just some inputs to consider.