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Discussion Starter · #1 ·
Definition of \"Oversteer\" and \"heavy steering\"

Hey guys, as some may remember, I've been doing some chassis experimentation with my 02 1k since having race tech valves put in my standard forks and shock. Since the install the bike has never handled the same.

Initially the bike would ride fine straight, compression and rebound seemed fine and in fact more responsive to changes in the road. Turn in however was a whole different story. If I "leaned" the bike using body weight at speeds of around 30mph, the handlebars would heavily turn into the corner as if a ghost was forcing the tire to turn in the same direction of the corner, if I tryed to countersteer it more the bike would resist quite to the point where the bike would be unstable due to my fighting the bike's will. After some pretty indepth investigation with no good results, we stumbled upon a recall on the tire that was on the front of the bike, and replaced it. That helped tremendously, but didn't get rid of it fully.

Months have passed and I've set the sag 3 different times. This past sag setting session, I decided to set the front and rear to 30mm of rider sag as a starting point, and then planned on tweaking from there. We managed to get the rear to exactly 30mm, with a spring set length of 181 according to my notes from last month (although just previous to writing this it measured out at 185mm). The front was set at 34 mm with the preload maxed out completely.

Today, I took off the race tech valved forks and installed a stock set of forks, setting them to stock measurements, the preload at the 4th line from the top, 3 lines showing. Haven't sagged out the new forks yet, but going off of feel, neither full out or full in feels right, having it set at the fourth line seems to be as good as it gets for now.

It seems that in my trying to set the sag the same front and rear, that I've found that I had to increase preload in the front (and the race tech forks are going back the mechanic to add 15mm of internal preload by fabbing another spacer with the added length). This seems to be the exact opposite of what all the recommendations are that I've read to address heavy steering and oversteer.

Am I understanding the terminology correctly in that what Im feeling in the bike being heavy steering or oversteer? The bike is rideable, but when trying to turn the wheel wants to point in the direction of the turn rather then allow for the countersteer. It's weird.

The tire is new, so that can't be the problem. The Sportec M1's tire pressure is at 36-37, so that's out. The steering stem seems straight, and the bearings good and greased. The stem nut is set at the specified torque with about a quarter of turn out before securing the lock nut. The only thing left is the steering geometry. But since I've sagged out the big to 34 front and 30 rear, it should be handling quite nicely in theory. But it doesn't. My GF's current 600 reminds of that everytime I ride it. I set up the chassis on that bike and it handles awesome. A light touch of counter steer and the bike lays right over, moving as incremently as I choose, and the front wheel stays pretty much straight, and "turns in" only on the slooow turns...as it should, and as my bike should. But my bike is not.

If anyone can give some insight that would be helpful.
 

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Re: Definition of \"Oversteer\" and \"heavy steering\"

It sounds like your bike is set too nose heavy geometry wise. It is oversteering in the corners (heading to the inside of the turn).

I had EXACTLY the same problem after having my suspension reworked front and rear. The forks settled lower on their new springs, which lowered the front too much, making the bike feel like it wanted to "tuck" in the corners.

I ended up maxxing out the preload, which still gave me 36-38mm sag!! The quick fix was to raise the yokes up the forks so they sat flush with the top of the top bolt, raising the front of the bike. This returned the neutral feeling you are looking for. Slightly firmer springs were the correct and final solution....

BTW. My understanding of heavy steering is the opposite to oversteer....the bike being hard to turn and slow steering??
 

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Discussion Starter · #3 ·
Re: Definition of \"Oversteer\" and \"heavy steering\"

Hey thanks for the FB man...I always thought that heavy steering, based on the description sounded a lot like what was going on with my bike before...so Im over here pitching it forward and getting info to raise the rear.

Then I heard the word oversteer a few months ago, and find that to fix the problem (through trial and error) that the it's the exact opposite.

The bike does feel harder to turn when going slow, and oversteers like mad going slow on cold tires. As they heat up it subsides a bit, but still there.

But thanks again for helping me to figure things out. Lets see if the theory is correct now. My mechanic is going to increase internal preload which should help...but Im using stock springs still front and rear so I don't understand how putting in the valves and using lighter oil could make that much of a difference on the chassis setup.
 

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Discussion Starter · #4 ·
Re: Definition of \"Oversteer\" and \"heavy steering\"

So then oversteer is caused from the front end being too low, and heavy steering is caused from the opposite....then whats understeer?
 

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Re: Definition of \"Oversteer\" and \"heavy steering\"

So then oversteer is caused from the front end being too low, and heavy steering is caused from the opposite....then whats understeer?
Understeer is when the bike won't hold a tight line, and runs wide to the outside of the turn when on the gas.

This is down to the rear squatting too much under power, taking the weight off the front wheel and reducing the steering effectiveness.

If you think of the steering as "fast" or "slow", rather than "heavy" or "light" it makes more sense.

In summary, fast steering (quick and easy to flick onto it's side) and oversteer (running to the inside of the turn) will be caused by over-steep geometry (too much weight over the front).

Slow steering (slow to turn) and understeer (running wide on the power) will be caused by too much rearward bias.

What you felt as "heavy" steering when trying to stand the bike up a bit mid-corner, was you having to fight the bike's natural urge to "pull" to the inside due to what I think might be over steep geometry.

I hope you get it sorted soon, it was a couple of very frustrating months for me trying to suss out the problem, especially after having spent out to have the shock and forks "improved"!! Was worth it eventually though........
 
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