Some thoughts (possibly bad thoughts)

[Cigar Mike]

It never occurred to me that there was a motorcycle made in this day and age that rear preload was not adjustable. I did suggest that making small adjustments is the way to go. I would have changed the geometry by raising the forks in the triples to prevent harshness by adding a lot of preload in the rear. But that is just me. There are limits to adjusting your suspension with a wrench. But it does work within those limits.

There is also a difference in how to ride different types of bikes. I have had to learn how to turn a street bike. On bikes with larger front wheels like dual sport bikes, when I lean into a turn I push the bike down keeping my body close to vertical. That is how you make tires stick in the dirt. It has always worked on pavement also with that type of bike. It seems to be the opposite for street/sport type bikes. I am still learning and don't have the confidence I had with the dirt method. I wonder if not changing methods between different types of bikes is also a factor in the pushing that is experienced. I definitely would ride the 690 differently than the NC. And expect them to handle the same obstacles differently. For that matter different tires on the same bike will handle them differently.

 

[Antarius]

I had a look at Racetech Emulators. They do not seem to do one specifically for the NC. From which model of bike did you chose to adapt them ?

They do make a specific Gold Valve Emulator for the NC700x. I ordered online, but you can call them directly. When you purchase them, they give you a code which gives you access to their database of "settings" for the emulators for your specific bike, with oil weights as well as how many turns out of preload they recommend based on the type of riding you want to do. (Preload on the valve).

Here's the link to the emulators: RT - Digital Product Search

FEGV S4101 is the part number. I believe they recommend 5wt oil (in the brand THEY sell).

 

[drdubb]

When turning on a street bike, push the inside bar by kissing the mirror. This tip has saved me more than once on a blind decreasing radius turn.

 

[Therapy]

When turning on a street bike, push the inside bar by kissing the mirror. This tip has saved me more than once on a blind decreasing radius turn.

I need a class.
Even with all my miles I am sure I taught myself some things pretty wrong.

 

[wildeone]

I need a class.
Even with all my miles I am sure I taught myself some things pretty wrong.

yeah, generally miles don't make you better rider - specific training does.
you can ride 40 years yet still repeating the same bad habits.

 

[Beemerphile]

Practice doesn't make perfect, it makes permanent. Training makes perfect.

 

[dduelin]

Yes, pushing the bike underneath you is not how to round corners on the street. If taking a high performance street or track course isn't available books like Total Control by Lee Parks, Sport Riding Techniques by Nick Ienatsch, the Twist of The Wrist books by Keith Code can help develop good riding skills. Then rack up the miles.

 

[670cc]

I don't know much about motorcycle suspension (meaning - nothing) but when I look at rear shock absorber spring, it looks to me like the most common linear rate spring. So, I don't understand how this "preload adjustment" can have effect on spring sag?
What I see that by turning adjusting rings clockwise make a shock absorber longer (to some extents) effectively raising motorcycle, but not changing characteristics of spring . Amount of sag under my weight remains the same. Center of gravity goes higher and this might have effect on riding performance (not mine).
Am I missing something?

The preload adjustment changes the motorcycle's loaded ride height. The adjustment positions the loaded ride height relative to the physical limits of the suspension travel, in order to best utilize that travel.

You are correct in that the preload has no effect on the spring's stiffness. The "preload" term comes from the procedure of putting some compression on the spring prior to mounting the unladen spring/shock absorber assembly on the motorcycle. Then, when the motorcycle is laden, the spring will normally operate within the boundaries of the shock's and suspension's physical limits. The term causes confusion in that some people believe it stiffens or softens the spring, but that is not the case.

 

[wildeone]

Yes, pushing the bike underneath you is not how to round corners on the street. If taking a high performance street or track course isn't available books like Total Control by Lee Parks, Sport Riding Techniques by Nick Ienatsch, the Twist of The Wrist books by Keith Code can help develop good riding skills. Then rack up the miles.

another words on the street rider is hanging off the bike on corners but while off-road, motorcycle is hanging off the rider

 

[Deleted member 1183]

There is also a difference in how to ride different types of bikes. I have had to learn how to turn a street bike. On bikes with larger front wheels like dual sport bikes, when I lean into a turn I push the bike down keeping my body close to vertical. That is how you make tires stick in the dirt. It has always worked on pavement also with that type of bike. It seems to be the opposite for street/sport type bikes. I am still learning and don't have the confidence I had with the dirt method. I wonder if not changing methods between different types of bikes is also a factor in the pushing that is experienced. I definitely would ride the 690 differently than the NC. And expect them to handle the same obstacles differently. For that matter different tires on the same bike will handle them differently.

This is an interesting subject. Like you I have a 690. I rode Enduro for years (many moons ago) on Kawasakis, and now just do a bit of trail riding on it. However with a dirt bike there is also the aspect of weighting the footpegs to assist steering and particularly the weighting of the outside footpeg in a turn to put as much weight as possible on the inside of the tyre in contact with the track. There is also the aspect of getting as far as possible up towards the steering head to weight the front end in some turns etc etc. I am not good at conveying much of this as it comes automatically to me and I rarely think about it. However, while riding a road bike on grippy tarmac is quite different, I still utilise some of my offroad practices on my road bikes. They come in very handy when one comes across gravel or dust on a tarmac road, or when riding in the wet. Time and time again I have found that lifting my backside slightly off the saddle and thereby weighting the pegs, has brought more control to the bike on slippery or wet surfaces. That way the bike is much more controllable if either of the tyres let go. Adopting an offroad attitude in such situations is also useful as you are ready for whatever the chassis might throw at you. I also practice letting the bike get a little loose on gravel when I see it on a tarmac road. I head straight for it and then deal with whatever happens. But the key to this is being ready.

Here in Ireland the local road authorities lay down fresh tar on damaged roads and then a layer of fresh stone chippings on top. The chippings stay loose for weeks. If one applies Road bike practices in such a situation then one will have some bad experiences. I actually enjoy riding such surfaces as it is an opportunity to apply the offroad practices to whatever road bike I might be on at the time.

Lastly, when riding the 690 on the road I sometimes apply road practices, as in leaning in with the bike, but only when using a round profile trail style tyre like a Metzeler Sahara, which reacts like a normal road tyre. If the bike is shod with kobbies however, then the sit up and drop in style that you mention is only used.

Just some thoughts . Now I think I will off out and enjoy a little of what I have just written about

 

[Triumph 'n Shadow]

Thanks Michael. Did I mention that I do have a Triumph and it can go "hammering" into the same bends without the slightest problem. I also have a KTM 690 Enduro. Perhaps my point is missed. Not to worry.

Hey Griff:

Awesome!!

Enjoy them all my brother of two wheels.

I bet riding the roads of Ireland is fantastic on any of the three you have.

God bless!!

Michael

 

[Deleted member 1183]

I bet riding the roads of Ireland is fantastic on any of the three you have.

Thanks Michael. Seeing as you are a Triumph owner also then the attached pic will be appropriate........

View attachment 25856

The Triumph was more appropriate to the roads on the day as they deteriorated a bit more, but my friend on the Pan managed very well indeed.

 

[Beemerphile]

...when I look at rear shock absorber spring, it looks to me like the most common linear rate spring. So, I don't understand how this "preload adjustment" can have effect on spring sag?
What I see that by turning adjusting rings clockwise make a shock absorber longer (to some extents) effectively raising motorcycle, but not changing characteristics of spring . Amount of sag under my weight remains the same. Center of gravity goes higher and this might have effect on riding performance (not mine).
Am I missing something?

Yep. Cranking on the preload does not change the static length of the shock. It is out against the upper stop before and after. It changes the sag because it changes the force exerted by the spring - but not the rate. The force exerted by a uniform spring is kx - the spring constant in pounds per inch times the number of inches it is compressed. The spring constant is the "rate". Assume the spring k is 100 lbs. per inch. Preload is the free length of the spring minus the installed length. If the preload is increased from one inch to two inches, the spring force increases from 100 lbs. to 200 lbs. This will reduce the sag and raise the unladen bike. However, regardless of the preload, an additional inch of compression will give the same 100 lb. increase in force. Increasing the preload allows you to get the same sag (say 1/3) with a higher load (heavier rider and/or gear) on the suspension. The reason that changing a spring is better than adjusting preload is in what happens when the bike encounters a bump. In order for the suspension to react properly in use, the heavier rider really needs a higher spring rate. He might ideally need say 150 lbs. per inch in order to use his full suspension travel. With the lower rate spring, he will bottom out the suspension more often than the lighter rider on the same course.

Multirate springs are different. They have different k values in different places. The lower rate (closer wound) sections are compressed first. Once the lower rate coils are bound (touching) the higher rate coils take over and the higher K is in effect. Progressive rate springs have gradually increasing coil spacing and thus gradually increasing (vs. single or stepped) k values.

 

[Antarius]

Good to have you back Beemer.

Awesome post.

 

[dduelin]

Yep. Cranking on the preload does not change the static length of the shock. It is out against the upper stop before and after. It changes the sag because it changes the force exerted by the spring - but not the rate. The force exerted by a uniform spring is kx - the spring constant in pounds per inch times the number of inches it is compressed. The spring constant is the "rate". Assume the spring k is 100 lbs. per inch. Preload is the free length of the spring minus the installed length. If the preload is increased from one inch to two inches, the spring force increases from 100 lbs. to 200 lbs. This will reduce the sag and raise the unladen bike. However, regardless of the preload, an additional inch of compression will give the same 100 lb. increase in force. Increasing the preload allows you to get the same sag (say 1/3) with a higher load (heavier rider and/or gear) on the suspension. The reason that changing a spring is better than adjusting preload is in what happens when the bike encounters a bump. In order for the suspension to react properly in use, the heavier rider really needs a higher spring rate. He might ideally need say 150 lbs. per inch in order to use his full suspension travel. With the lower rate spring, he will bottom out the suspension more often than the lighter rider on the same course.

Multirate springs are different. They have different k values in different places. The lower rate (closer wound) sections are compressed first. Once the lower rate coils are bound (touching) the higher rate coils take over and the higher K is in effect. Progressive rate springs have gradually increasing coil spacing and thus gradually increasing (vs. single or stepped) k values.

Lee very effectively explains how preload reduces sag without changing the stiffness of the spring but goes off track saying changing the spring is better than using preload. This is only true if the spring rate for the heavier rider is too soft to begin with. If the spring rate is correct - a range - "in the ball park" - the shock can use most of it's available travel without bottoming or topping out in the range of operation the bike is normally used in.

Preload is an adjustment that allows riders of a given weight range to set sag to an acceptable level and still add add weight of passengers or luggage/cargo. The shock manufacturer has to choose a spring that can work adequately for a given range of weights and preload allows this adjustment. The goal is to adjust the shock so it sags about 25 to 33% of it's available travel and still have the shock operate in the middle 1/3 of it's travel, allowing the upper 1/3 and bottom 1/3 for bumps and holes, drop-offs, etc that move the shock in use to near to it's upper and lower limits without actually reaching them.

Definitions:

Static sag is the amount the suspension compresses under weight of bike and riders(s) plus any cargo.
Free sag is the amount the suspension compresses under weight of bike alone - no rider(s) and cargo. 5 to 10 mm is needed for normal street biased rear suspensions.

The relationship of static to free sag numbers indicates if the spring rate is correct.

If the bike has enough preload adjustment range to show acceptable static sag but then measures little to no free sag then the bike alone does not compress the suspension much at all. The shock is almost topped out without a rider. Adding weight of rider(s) and cargo blows right through the preload force -clearly excessive preload was required to set static sag. This shock spring is too soft, is likely to bottom out under hard use, and would benefit being changed to a stiffer one that needs less preload to set static sag. The shock will operate in the lower 2/3 of travel and give up the upper 1/3 of travel.

If the bike requires little to no preload to set acceptable static sag and shows 5 mm or more of free sag then the spring is too stiff and is likely not to use all of the shock's travel and will give up the lower 1/3 of travel - too stiff.

 

[lootzyan]

...Cranking on the preload does not change the static length of the shock. It is out against the upper stop before and after...

Thank you Lee for clarifying that. I was under wrong impression that turning adjusting rings changes overall length of shock, something I didn't want to do because I already lowered a frame. Turning rings CW is adding compression to spring and of course is effectively changing deflection rate of spring under the same weight.
NC's maximum weight capacity is 461 lb. With my pillion ballast and "stuff" we are about 350 lb so I shouldn't be afraid of bottoming out or should I?. My wife is already complaining on bumpy ride (poor dumping). I just wonder if changing compression (preload) would improve ride comfort to some extent?

 

[670cc]

If you were sitting on the bike and adjusted the preload rings, the spring length would NOT change at all. It would simply raise and lower the rear of the bike.

Picture a spring sitting vertically on the floor. You put a weight on top. The spring compresses some. Now for the preload adjustment, you slip a 2 inch block under it. Now the weight just sits 2 inches higher in the air, but the spring does not compress any more.

 

[Antarius]

Turning a preload collar does compress the spring. It's "preloading" the spring.

 

[Beemerphile]

Lee very effectively explains how preload reduces sag without changing the stiffness of the spring but goes off track saying changing the spring is better than using preload. This is only true if the spring rate for the heavier rider is too soft to begin with. If the spring rate is correct - a range - "in the ball park" - the shock can use most of it's available travel without bottoming or topping out in the range of operation the bike is normally used in.

You are correct Dave. I made the assumption (with comments such as riders of up to 280 lbs. and "cranking the preload all the way") that the spring was out of range. It may or may not be. Your method of determining that is spot on (as usual). I have seen riders try to treat the two as interchangeable and that was the error I was attempting to illustrate. Extra preload doesn't fix a too soft spring without creating other issues. I'm wondering what the free sag is with the preload cranked to the max, and am thinking it might be pretty close to none - indicating a too soft spring. It is amazing how a correctly tuned suspension can be both firmer and plusher at the same time. It seems counter-intuitive, but a firmer spring with less pre-load can be both more compliant in the top third and more resistant to bottoming in the lower third. The too soft spring, cranked tight, can be less compliant because the preload that was added in an attempt to prevent bottoming makes it unresponsive at the top.

 

[dduelin]

You are correct Dave. I made the assumption (with comments such as riders of up to 280 lbs. and "cranking the preload all the way") that the spring was out of range. It may or may not be. Your method of determining that is spot on (as usual). I have seen riders try to treat the two as interchangeable and that was the error I was attempting to illustrate. Extra preload doesn't fix a too soft spring without creating other issues. I'm wondering what the free sag is with the preload cranked to the max, and am thinking it might be pretty close to none - indicating a too soft spring. It is amazing how a correctly tuned suspension can be both firmer and plusher at the same time. It seems counter-intuitive, but a firmer spring with less pre-load can be both more compliant in the top third and more resistant to bottoming in the lower third. The too soft spring, cranked tight, can be less compliant because the preload that was added in an attempt to prevent bottoming makes it unresponsive at the top.

Well, you and I shouldn't have to crank the preload to the max to achieve good static sag so the end result is that free sag is in an acceptable range. However, using the example 280 lb rider now that would probably require max preload and yes, the spring would be too soft for him. Like any other adjustment if all of the adjustment is used up in the adjustment than the thing being adjusted is not the right application.

IIRC the free sag after set up for my 150 lb weight was about 8 mm. It's buried somewhere in this forum about a year ago.

PS I'm going to be passing through Danielsville Thursday between 12 and 2 PM as best as I can guesstimate, northbound in great haste but if you are up for a bottle of water I'm buying.