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Race sag:effect on cornering??

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#1
Just wondering how would too much/not enough race sag effect cornering. I know Ive got too much right now just havent gotten around to resetting it yet. Im a little guy 5'7"-5'8" 130lbs geared up. I was messing with tire pressures and found when I ran on the low side it made a huge difference in railing sandy berms but was wondering if the sag was also a factor.

The bike rides great on whoops, doesnt bottom on jumps so im hesitant to change it. But if I get a response that proper sag will make it corner better ill get on the adjustment.
 
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#2
Leave the tire pressure work to nascar guys. Your manual says 15, 15 it is. You are trying to get it to corner? The same people who came up with the 15 psi in the tires, tell you to run the sag at 4 inches. Smoother tracks run more ,and the rougher gets less sag. After you get your 4 inches of race sag, check the static sag. I am sure you will need softer springs.
 

IndyMX

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#3
whenfoxforks-ruled said:
Leave the tire pressure work to nascar guys. Your manual says 15, 15 it is. You are trying to get it to corner? The same people who came up with the 15 psi in the tires, tell you to run the sag at 4 inches. Smoother tracks run more ,and the rougher gets less sag. After you get your 4 inches of race sag, check the static sag. I am sure you will need softer springs.

Huh.. I like my pressure around 13 psi..
 
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#4
IndyMX said:
Huh.. I like my pressure around 13 psi..
Let me guess, the ex bridgestone guy? Tube pincher! A couple pounds probably would not hurt? The tire and the book usually tell you 15 psi. It helps the tire from spinning and pinching. the rest is form and set up. And fear! Springs and sag, then fiddle with the clickers. It will corner, its up to the rider.
 

SpDyKen

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#5
I alter my tire pressure based on conditions. I would only run my tire pressure as high as 15 psi. in rocky, or high-speed hard-pack conditions.

It is my perception that many off-road racers do the same. I think pro MXer's do, also, but rely on the tire mfgrs. to provide them the proper pressures for each track & conditions.

As a former road racer, I varied tire pressure to affect traction and wear, all of the time, but used the tire maker's recommendations to start.

I'm pretty sure that that dirt-trackers alter their pressures, as well.

I can tell the difference in 1 to 2 psi., when I am riding. Different tire & tube combinations require different pressures, also, IMHO.

Your suspension sag greatly impacts your bike's steering. This is why the factory teams spend so much time testing. There are many, many, variables that need to be tested, in conjunction with each other. :nod:
 
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#6
So did I read anywhere how too much/not enough sag will affect cornering?
 

James

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#7
I read where you mentioned tire pressure first :)

Sag will affect cornering. Too much slows the steering, too little steepens the steering. Both affect the way your suspension reacts. You will have to experiement to find out whether you corner better with more/less sag.
 

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#8
I ride almost exclusively in roots and square edged rocks and sometimes run as low as 10 lbs. no pinch flats yet.
 
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#9
I'm with SpDyKen 100% on his tire pressure views.

If you don't have enough sag the bike can become twitchy and unstable. It can even cause headshake. Too little sag and you'll be pushing in corners.

Proper sag is very important in overall suspension performance as well. Some guys claim they can feel a 1-2mm change. I'm not that good, but I keep my sag right around 102mm all the time. I don't change sag for conditions, only the compression/rebound settings.

The only time you should really change sag is riding mud, where the extra weight of the mud will effect the sag. Otherwise pick a number and stay with it.
 
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#10
Ken is right on, for trails and what not. Kawraper sure did not specify. Specify what you are intending on riding , before the trials guys get on this! But I took it at MX racing, 13 to 15 is good. Trails are a lot different than a nicely groomed MX track. Set the bike up as called for in the manual, its a very good baseline. Learn to ride it, then see if it is pushing the front end, or knifing. And do not go with too much sag that you are bottoming a lot on jumps and what not. The more sag the better it will set in the corner and power out! You get fast enough and bottoming in the corner starts happening. When you get that fast, you will see why new tires are appreciated every week. Sell the old ones to the trail guys? 4 inches outdoors and 3 3/4 for sx.
 
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#11
Ok that was a little more what i was looking for. I know I have too much sag for sure. It pushes in the corners but was wondering if that pushing could be due to the sag. I ride mostly mx so railing the berms is what i want. A little more oversteer. Ive been washing out alot and dumping the bike and it needs to stop. I want to be good enough to do a little racing b4 the end of the season but got a lot of work ahead of me. That means I need alot of seat time and the right setup.
 
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#12
Baja should have some open practice coming up, Redbud is this weekend, 4 hour drive? Unless you are a computer, get a log and keep track of what works better and where at. 130lbs with gear? Try Jeremie's spring calculator, that is step one, I am sure you need a few sizes smaller springs. http://www.mx-tech.com/
 
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#13
I dont think im ready for red bud yet. Baja is on the list. I just started riding in like june of last year then sprained my ankle and lost a month and blew up my bike in sep so it was a short one. I rode mostly holly family track last year so far this year a private track out by the palace and another on the east side. Only been out about 5 times.

I leave for nyc for 2 weeks 2morrow for work wich sucks but it just snowed for 2 days and the tracks were pretty much a disaster any way. Hopefully its nice and dry when i get back.

I think ur right on gettin some different springs. I cased a jump the other day and smacked my chest off the bars but didnt even bottom the forks out....
 
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#14
Riding a bike with too stiff a set up is dangerous to say the least. I would much rather ride a soft bike, and just slow down for the gnarly stuff.
 
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#15
Most bikes race sag is 100 or 105. I tend to always run 102mm on my Hondas 450.
Tire pressure. Just about every magazine recommends 12psi for racing. Yes the manual says 15psi to protect the rims from getting a flat spot. I always run 12psi and never have an issue. On tracks that I am having traction issues I run as low as 10psi and it does help in traction. I only weigh 178lbs and have not had an issue. Heavier riders might have to stay with the 12-15psi range. I also check the tire pressure before and after motos becasue the pressure creeps up during a ride.

Sag: sag at 105-108mm helps the back end feel a bit plusher on small edge bumps and braking bumps. the trade off is the wt on the front tire is less so can wash out on flat turns. I run 102mm to ensure I have enough wt on the front tire to grip on flat turns.
Also note, the less sag also makes the front end a bit rougher also due to the extra wt on it. If you have a good fork it ok to run 100-102mm.

Spokes572
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