Quote:
Originally Posted by Navigator
I am seriously considering installing a steering damper now. I know these things are costly but don't want this slapper to happen again. Will a damper help? I have never ridden a bike with one before.
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A steering dampener help a little but I find in order for them to save you from this they have to be very tight and you may not like the ride the other 99.9% of the time.
If this was a surprise incident then its possible you slammed on the brakes bottoming the forks quite hard instead of applying the brakes quickly and progressively and as they reached the bottom of the stroke you were then at 110% braking power. We're splitting hairs here when you look at the difference between the two methods when in relation to time but both methods will have very different effects on the chassis response. For simplicity we'll slamming on the front brake in a panic method #1 and applying maximum braking power method #2
Method #1 becuase the ninja's front suspension is so soft and the chassis isn't as ridged as some the bikes it will respond differently to this method. When you slam on the brakes the forks with dive and immediatly bottom out cuasing the rear wheel to lighten up and try to lift off the ground. But while this is happening the torque in the chassis is still trying to catch up in a hurry a d if the rider is slightly heavier on one handlebar then the other or the road surface isn't perfect it can cause the chassis to flex in a horizontal direction instead of just purly lateral.
First road conditions could be anything for sand/debris to surface undulations and they only need to be minor in order to effect the bike when its being applied maximum effort.
Second handlebar input like road conditions only need to be slightly off to cause an influence and its nearly impossible to avoid this entirly for any rider so I would worrie about it to much. When your hard on the brakes you hand position of your left vs right are totally different because your right hand is holding a brake lever. This will cause the pressure being applied to the bars to differ slightly and when you rear wheel is nearly off the ground you no long have to points of stabilization to help compensate. Rear brake if used is also another variable but I'd say more so in relation to road conditions.
When your chassis flexes under load it acts like a spring and like any spring it will need to rebound eventually and this is where your tank slapper starts from. After the first slap it only gets worse because your still compressing the spring(bike chassis) by applying continuing to apply the front brake so the chassis continues to compress and rebound from left to right down the road.
A steering dampener like most rider aids act as a bandaid to act as dampener for rider or road impurities. In a perfect world you wouldn't need them but its not perfect so they are needed from time to time. Please to argue with me about how all racers use steering dampeners on thier bikes so they must be needed. First most pros have them because they are sponsored so it looks good to have it on the bike for said sponsoring company. Second even if we have it at the very lightest setting doing nothing 90% of the time it convenient to have it there just incase an imbalance in chassis setup occurres that can't be solved so we just give it a few clicks to help until we can solve the problem. Something's the problem is never solve so the dampener is always at a mid setting to keep things from getting out of hand. So a steering dampener may have saved you but at this point we will never know for sure and if you had responded just a little different you may also have saved it but at this point we will never know.
Method 2 has all the same effects as method 1 but the effects are reduced greatly because they were eased into instead of impacted. Method 2 is what you have to use going into every corner when racing fast on stock suspension. basically you apply the brakes in a progressive fashion so you ease the forks into the bottom bumper without shocking the chassis then you continue to apply most braking force loading the chassis progressively so the overall maximum load applied to the chassis is much less then when you impacted it from slamming the brakes in method 1. With less overall less load and no impacting force being applied to the chassis it won't have excess energy stored in it so it won't need to rebound while still applying brakes. So no horizontal defection and no head shaking.
Now onto why other bike are less prone to this outcome but not in any way immuned. Most other bikes with equally soft front suspension as the Ninjette typically have more rake in the front end(like a chopper) so the chassis dynamics are totally different and much more forgiving. As for other sportbike with similar chassis dementions, well they will normally have stiffer valving and springs. With stiffer suspension even when slamming on the brakes the impact when reaching the bottom of the forks is reduced because you had to first get through the suspension first. Also if we're talking a more modern sport bike then it will have a much stiffer chassis that's less prone the flexing so it won't have a rebounding effect. Now I will say that if you manage to flex a current generation chassis then the volatility of the energy stored is much greater then on the Ninjette and when released it can be very violent. For this reason most sportbikes come equipped with steering dampeners.
I know that was a long explanation and honestly I made all of it up as I typed based on theorems I thought of as I went but it all seems to make sense in the end so I hope to could find it useful.
If you want to help prevent this in the future
1. use method 2 by practicing it all the time by doing a trackday on the Ninjette, this is by far the hardest of the three options I'm going to give you.
2. Equip a steering dampener and hope it works, I can't say I'm fond of this solution but to each his own I guess.
3. Fix your front suspension to handle the extra load applied in an emergency and when paired with method 1 it works even better. As to fixing the suspension I have a thread in the works currently that reviews the changes I've made to mine last week that fixed every issue including the one you experience and many more. So keep an eye out for it over the next few days.
Best of luck with your full recovery.
Ps. I didn't proof rear this and did type it on my phone so.....well you get the idea
