[ironsurfer129]

motorcycle tire slip?
I have 00 yamaha r6 with dunlop qualifier tires.
Today when i did a hard brake at 50ish miles, my rear started fishtailing and skid toward one side, and i reapply the brake and kinda got the bike straight but i was out of the line at the red light, lucky it just turned red from yellow.

What could be the problem? Tires or brake?

 

[snowbizx]

are u keeping the bike in gear as u brake? once u pull in ur clutch, ur gonna drag that rear wheel pretty easily.

 

[tasmike]

Is it the first time this has happened?
Might just be some road grime and when downshifting/braking the rear has lost some grip, gone into a skid and the bike will start going to one side.

Just my 2c.

 

[ironsurfer129]

Actually today is the first time it happened, and later on that day it happened again.
I think like other said, i use my rear brake too much because my front brake is really weak. I really need to get that fix. But from what a shop said, my front brake was just coated with fork oil because it was leaking. I changed th fork seal and cleaned the brake rotors. but one of the rotor still has grease on it while the other is dry. What other way to clean that oil off or should i be safe and go with a new rotors + pad?

 

[VTchemist]

careful releasing the rear brake if you lock the back tire. if the bike isn't straight, that's a recipe for a highside. if it goes sideways, keep the rear locked until you stop.

 

[mojo]

Get your front brakes fixed asap this is where most of your braking comes from. Replace the pads as they are probably soaked in fork oil and use some brake cleaner to clean the rotors.

It is easy to lock up the rear brake no matter what type of tire you have on a sport bike especially if you are trying to use it as your main brake. The reason for the fish tail is to much rear brake.

 

[gravis86]

I've gotten the rear to slide quite a few times under hard braking. ut the first time I pitched it sideways was yesterday at a stop light. I was only going 10 mph, so the only thing I could think of that would make it lose traction that bad is all the oil on the ground.

 

[ironsurfer129]

Could going downhill be one of the problem too because i was going downhill
In theory, more weight in front because of downhill. Now i remember the 2nd time i did it last night was at a downhill as well.
If thats the case, is there better way of braking while going downhill?

 

[gravis86]

Normally when I go downhill, I downshift and use the front brake. The slipper-clutch usually does its job pretty well.

When I locked it up yesterday I was going downhill, and the road was slightly sloped down on the right. That's why my tail end kicked out to the right. I normally wouldn't have used my rear brake in that situation, but I had to stop as soon as possible. The guy in the car next to me gave me a weird look, too.

 

[fyrefyter0143]

remember about when you apply the brakes hard, all that energy has to go either up (stoppie) or sideways.

 

[Jrjones]

You can lock up the back tire at any speed, even walking speed. Bad habit to rely on your rear brake b/c in an emergency you'll likely stomp it, causing you to skid around.
I only use mine on inclines and slowly coming to a stop, (ie. stop and go traffic).
Colder your tire is the easier it is for it to skid too

 

[maxx rs4]

You can lock up the back tire at any speed, even walking speed. Bad habit to rely on your rear brake b/c in an emergency you'll likely stomp it, causing you to skid around.
I only use mine on inclines and slowly coming to a stop, (ie. stop and go traffic).
Colder your tire is the easier it is for it to skid too

Maybe I misunderstood your post but that doesn't sound right to me. I always use the rear brake AND the front brake. That way if I'm in an emergency I can hit BOTH brakes without hesitation to minimize my braking distance and have a better feel for the limits of both. If I didn't always use both brakes, I bet I'd be more likely to under use or stomp on the rear !

 

[Mr. Bigg]

get new pads and clean you rotors with brake parts cleaner. It is about a dollar at o'reilys

remember about when you apply the brakes hard, all that energy has to go either up (stoppie) or sideways.

actually most of the energy in converted into heat.

 

[Oregon R6]

Maybe I misunderstood your post but that doesn't sound right to me. I always use the rear brake AND the front brake. That way if I'm in an emergency I can hit BOTH brakes without hesitation to minimize my braking distance and have a better feel for the limits of both. If I didn't always use both brakes, I bet I'd be more likely to under use or stomp on the rear !

You can still lock up the rear if you use the front brake. That will cause the rear to get loose.

You can also get the rear loose by using so much front that the rear becomes unweighted - it will float around if that is the case. Happens to me here and there on the track if I brake harder than normal for some reason - but easier to diagnose there as I know what is causing it...the rear end getting light from heavy front braking

Other factors come into play - suspension, grip of tires (function of pressure, temp, condition of tire), grip of surface, body position (how much you are weighting the F or R), etc.

It can also be (and likely is) attributed to a variety of factors working together, so very hard to say what the root cause is just by the description you gave.

Any way you cut it, the bike is giving you feedback - that the rear is losing traction. Harder part (since, like I said, we can't say "It was caused by X") is figuring out how to incorporate that feedback into your riding. But that is the normal maturation of a rider - figure out what the bike is telling you and figure out how to adjust your style to compensate...if you can do that, you are well on your way to becoming an accomplished rider.