if you goin to fast maybe try to engine brake to.

 

No, nothing wrong with the bike. It's just a matter of not having enough weight focused on the rear wheel to maintain grip under even moderate braking. As you brake (with either wheel), your momentum wants to keep going forward past where the bike is. This turns the front wheel where it comes in contact with the ground into a fulcrum and and the rest of the bike into a lever. Momentum is the force acting on the lever trying to rotate it around the fulcrum. Under normal braking, the front loads and the rear lifts a little bit, but stays planted. The thing to remember is that the rear wants to keep moving forward any way it can around that fulcrum, over or around. So long as the bike is upright, traveling in a straight line, and both wheels are on the ground, you're fine. As soon as there's any lateral motion (i.e. a turn, slight variations in the road, minute movements by the rider), that's enough to nudge the rear into a fishtail.

Hope that's what you were looking for.

 

That technically has the same affect as too much rear brake. They're both slowing down the rear wheel. If the rear is light from the front loading too much, either one will cause a fishtail.

 

Assuming everything is in working order, you guys prolly need to practice braking in a parking lot. It sounds like y'all are too heavy with your right hand. Sounds like you're grabbing the brake. Not enough to lock the front wheel. But more than enough to overload the front suspension while the rear hasn't settled.

 

Well thank you kowen and kuroshio! To the Parking lot! ill ease up on the rear brake and as kuroshio said Im not giving enough to lock up but enough to overload...hopefully this fixes your problem as well choleaoum!

 

Sportbikes get 90% of their braking power from the front. Applying front brake loads the front, lightens the rear, and it takes much less to lock it up or lose traction. The rear brake is great for grass and gravel, very slow tight turns and some advanced techniques, but in normal riding it can end up causing issues.

If you do a stoppie unintentionally, you grabbed too much front brake.

Cruisers and touring bikes need the rear brake much more than we do, and MSF teaches its use, but we're on sportbikes, which behave differently. In reality, on the street, I rarely even touch the rear. On the track, I use it, but we teach novice and intermediate track students to use front only. Not until very fast advanced training do we introduce the rear (and we don't introduce turning and front trail braking until experienced intermediates...and of course, don't try trail braking and advanced techniques except under the supervision of a qualified instructor, and always practice new techniques in a controlled environment).

 

Thanks for bringing that up. A little more on the topic:

Sport bikes have a relatively high center of gravity, which works to amplify the unwanted effects of braking. A cruiser, for instance, has a longer wheelbase, shorter overall height, weighs more, and places the rider further back between the wheels. All of this helps improve stability and keeps the rear planted. The drawback, of course, is agility.

 

Funny thing...before my lowside I used the rear a lot. Now, I barely touch it. Only when the light turns red and I don't think I'd make it. Of course my foot is on it while lane splitting. CA ftw!

 

Go watch a motoGP race. Half the time the rear wheel is just barely coming off the ground from braking with the front. Stop using your rear brake. Once you get completley comfortable braking with the front only then start practicing your rear application. The only time I put any real effort into the rear brake is when Im riding 2 up and need to stop very quickly.

 

There are practical reasons to practice using both brakes. In panic stops people rarely think. They rely on muscle memory. If using the rear brake isn't part of that muscle memory, it may not get used and they might not stop in time because of it.

MotoGP is a horrible example to a street rider. They have expertise most of us will never get close to, ride bikes that have been tuned beyond most our wildest dreams and ride on in an environment most of us won't get to. And randyjoy will tell you they do use the rear brake regularly. How they use it is an advanced technique that really has no application on the street and must be practiced carefully. But in this particular case, these guys are fishtailing when using both brakes in a straight line. That doesn't bode well if they have to emergency brake for real.