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Can somebody explain suspensions to me?


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For the past 6 years I have been riding a 2006 Vstar 650 Classic,  It's pretty much the only bike I have owned besides my starter bike which was a 2009 Honda Rebel which I traded off for the Vstar.  Suspension was never anything I worried about or even discussed because a cruiser isn't really something where different suspensions and suspension settings are a big deal except for comfort.  But switching to an adventure style bike such as the FJ-09 I am finding that there is whole new world out there.  One aspect of this world that is totally alien to me is suspensions.  I notice that many people change out their suspensions and do a lot of tweaking and tuning their suspensions.  Why is that?  Is it a comfort thing looking for a nice cushy ride?  Or is it a handling thing where the bike handles better going around corners at high speeds and stuff.  I mean when I bought my FJ-09 the first thing I did when I got home was put the rear shock on the softest setting hoping to get a little less seat hight because I have really short legs and it sucks feeling if there is a pothole or uneven ground when I put my foot down i'm screwed.      Other than that I dont know jack shite about suspensions.  Can somebody explain what this is all about?
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For the past 6 years I have been riding a 2006 Vstar 650 Classic,  It's pretty much the only bike I have owned besides my starter bike which was a 2009 Honda Rebel which I traded off for the Vstar.  Suspension was never anything I worried about or even discussed because a cruiser isn't really something where different suspensions and suspension settings are a big deal except for comfort.  But switching to an adventure style bike such as the FJ-09 I am finding that there is whole new world out there.  One aspect of this world that is totally alien to me is suspensions.  I notice that many people change out their suspensions and do a lot of tweaking and tuning their suspensions.  Why is that?  Is it a comfort thing looking for a nice cushy ride?  Or is it a handling thing where the bike handles better going around corners at high speeds and stuff.  I mean when I bought my FJ-09 the first thing I did when I got home was put the rear shock on the softest setting hoping to get a little less seat hight because I have really short legs and it sucks feeling if there is a pothole or uneven ground when I put my foot down i'm screwed.      Other than that I dont know jack shete about suspensions.  Can somebody explain what this is all about?
Sometimes ignorance is bliss. Most people complain about hitting a sharp edged bump at speed. It feels rather harsh. Another thing is the tendency to get some front end wiggles going at about 80mph, leaned into a turn, and hit a bump. Both things are corrected by an upgraded suspension. If you don't ride fast or mind the occasional teeth shattering over sharped edged bumps, you will be fine. My bike railed just fine going very fast, but I like to tinker.  
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2015 FJ-09, Seat Concepts seat cover and foam, Cal Sci medium screen, rim stripes, factory heated grips, Cortech Dryver tank bag ring, Modified stock exhaust, FlashTune with Graves fuel map, Cree driving lights, Aux power socket.
2012 Street Triple type R (Wifes)
2007 FJR1300 (Sold!)
 
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Shadow- I want to echo what ULEWZ said- the suspension action on the FJ-09 is fine for most. I found some head shake at certain times and leaned over, mid-corner bumps upset the chassis more than I'd like. Also, for two-up, I had to firm up the rear, using pre-load only and it made the bike harsh. With a proper spring, I can made adjustments to the compression damping and get a smoother ride for me and my passenger. I can also firm up the bike, on the fly with my new setup. For about $1300 and a day or so of work, I found a setup I like and I'm pleased.
 
And yes, I like to tinker, too.
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Yes, there is a lot to motorcycle suspension, but the good news is that there is a lot of material to help you understand it. One very good source is www.motorcyclistonline.com, MC Garage, and videos by Ari Henning. Or any of the motorcycle publications really. Dave Moss is also a very respected authority on motorcycle suspension. Once you understand the basic theory, you will have a basis to start tweaking your bike's suspension.
 
You don't just want to "set it to it's softest setting" because that will not allow the stock parts to come close to working the way they are capable of. Baseline setup is very much dependent on your weight with gear as it allows the suspension to get to it's middle position so it has travel to accommodate both bumps and dips. At a minimum, get your preload set up to get you proper sag measurements and then tweak from there.
 
 
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So from what I am gathering with these bikes suspension is pretty important. Not sure how much though. I am not a huge speed demon but then again riding around on a Vstar 650 there isnt much there to work with. From what I have been reading suspension seems to be something that factors greatly on high speed cornering like going through the twisties and such. Its not so much about the softness of the ride going down the road but keeping your tires in contact with the road at all times no matter what. (I think that what this all means...) Once I get my lowering links I will probably tweak my suspension and get the proper sag set up to be on the safe side. Right now I go thru corners just fine and feel pretty safe but then again my inexperience to this style of riding it could be way off and I just don't know it. Am i getting any of this right or am I way off?
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you can get away with 'murder' at up to modest highway speeds and rational lean angles. Given your ownership history you don't know what good suspension can do or feels like. That's ok. If you're <200lbs the stock components will function "just fine" for many people's definition of "fine". And I'm sure there are plenty of folk who wonder what these suspension nuts are blathering on about...
 
If possible I might recommend a different saddle solution vs just throwing lowering links at the problem but I don't know how much height deficit we're talking about nor your comfort zone. My solution to potholes and uneven ground is don't stop where you'd put your feet in one and scan the road to identify such features. :)
 
But if you can't solidly put the balls of both feet down on flat pavement, then sure, I can appreciate your anxiety.
 
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BTW, Pattonme is also a very good source of suspension information, and he's right here on this forum!
 
The reason setting up and adjusting suspension on a motorcycle is so important is simply because of the weight of the vehicle versus the weight of the rider. Your FJ-09 weighs, say 450 pounds fully fueled and with bags. Your weight is say around 200lbs fully geared up. Someone else's weight may be 150 pounds whereas a third person may be 250lbs. That's a 100lb swing which equates to almost a 20% difference in total weight of vehicle & rider. Throw a passenger into the mix and that ratio can double.
 
Rider weight is a much larger component in the vehicle+rider equation for a motorcycle than it is for a car (an order of magnitude different), so the adjusting a motorcycle's suspension for a particular rider is much more important than doing so for a car. The lighter the bike, the more pronounced the difference is (Ninja 250 = 300lbs), and the heavier the bike the less pronounced the difference is (Harley-Davidson Electra Glide 950lbs). That's why motorcycle guys talk so much about suspension.
 
The same principles apply to cars, but the driver's weight is a MUCH smaller component. Ever throw a bunch of 50# bags of water softener salt in the back of your car and notice how different the car/feels driving home? Same thing as adding a passenger to your motorcycle.
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If possible I might recommend a different saddle solution vs just throwing lowering links at the problem but I don't know how much height deficit we're talking about nor your comfort zone. My solution to potholes and uneven ground is don't stop where you'd put your feet in one and scan the road to identify such features. :)
 
But if you can't solidly put the balls of both feet down on flat pavement, then sure, I can appreciate your anxiety.

 At the moment as the bike sits stock I can't put both feet down.  If I stretch as far as I can, I can get my tippy toes of both feet down, but there is no stability at all as far as keeping the bike upright.  I can rock over to my left side a little and get my left foot down on the ball of my foot.  As well balanced as the FJ is that is all I need.  If the surface is uneven or there is a hole and I am unaware of it, it gets kinda scary.  Last thing I want to do is look totally stupid dropping my bike at a red light.  Having to maneuver the bike around while sitting on it is out of the picture completely.  I have to maneuver it around by walking it around.  I'm getting the lowering links in today and I just ordered a lowered seat off ebay.  Surely that will make the bike much more comfortable as far as sitting stopped and moving around.  I have been in the market for a new bike and I loved how I get the best of all worlds with the adventure style bike.  A little sport, a little cruiser, and the FJ-09 was the only one I could actually throw my foot over and rock it up off the kickstand which was completely impossible with the Vstrom, BMW or Versys.  Being short sucks, but when you are built like a giant midget like me (5'6" with a 25" inseam) it really sucks.
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The primary purpose of suspension is to keep the wheels on the road. That is important because you can not brake, steer or accelerate while air-born. The secondary reason is to reduce the jarring (and so increase the comfort) from bumps and other imperfections on the road.
 
Things that push the wheels off the road include bumps and wheelies. Things pushing the wheels onto the road include gravity acting on the weight of the bike and rider. The spring is there so a bump can push the wheel up out of the way and only some of the force goes through the spring to push the rest of the bike of the road. When the force from the bump has gone away, the spring then pushes the wheel against the weight of the bike to push the wheel back onto the road. The damper is there to stop the spring from behaving like a pogo stick.
A spring has a strength, which is how much force is required to compress or expand it a given distance. Changing the preload does not change this force, it just changes how much force the spring is already under and so how much more force is required before it starts to move. Setting "Static Sag" is adjusting the preload for the weight of the bike and rider so it is in the middle of the springs working range. If you have too much preload, the spring cant compress to absorb shocks. If you have too little, the spring cant expand to put the wheel back on the road.
If the bike is too heavy for the spring then it can't absorb enough force from the bump and the bike will be jarred. If the bike is too light, the inertia of the bike wont let the spring compress to absorb the force.
Too much damping means stops the spring from doing its job. Too little damping means the bike will bounce up and down after the bump has passed. This is a serious problem for cornering because the rate of turn is proportional to the length of the forks, and if the bike is bouncing, the length of the forks is changing.
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