Lean angles; Dirt vs Road

[J Farrell / Speed Tech Motorsp]

Hmmm...... Maybe I should start a racing school? The question of why riding styles differ from dirt riding to roadracing.
It all has to do with center of gravity and the amount of traction available. On asphalt there is a bit more traction to be had than there is on dirt or ice. On dirt or ice you are always sliding because there is less traction available.

Senerio 1: On Dirt: If you were to hang off the bike towards the inside while the tires aren't gripping and the bike wants to slide towards the outside of the turn because your coming in too hot. You would fall down towards the inside because you don't have weight over the tires to keep traction. So sitting on top of the bike on the dirt while it is sliding only helps the bike gain more traction.

Dirt bikes are much taller than streetbikes.
So when you lean it over, your weight has more pull on the makeup of the center of gravity between you and the bike. So if you hang off the bike the center of gravity is futher away from the tires towards the inside of the corner and not over the tires where it needs to be. Because on dirt there is a whole lot less traction available so the center of gravity needs to be over the tires.

When you exit a turn on a dirt bike you need weight over the rear tire straight up and down to get it to bite into the ground to prevent spinning. Once it starts digging in then you transfer weight to the front to keep the front tire front coming up.

Senerio 2: On Asphalt Roadracing Bike:
Lets say you decide to ride like you were on your dirtbike while roadracing. Big problem which I see many begining riders do, leaning away from the inside of the turn. Again it is all about center of gravity and the amount of traction available.
You need to hang off slightly towards the inside of the bike only once up to speed. Why do I say once up to speed? Because for riders who want to just get that knee on the ground it limits their cornering speed because they think they are as far over as they can get.
Alright lets say you do hang off the opposite way through a turn at racing speed. You wouldn't make the turn at the same speed as when you rode while slightly hanging off the inside because the center of gravity is further away from the inside of the turn and the bike will have to be leaned over farther to make the same turn. Well if you were already leaned all the way over while slightly scraping your pegs normally and you decide to hang off the opposite way now! You wouldn't make the turn because you wouldn't be able to lean the bike over any further since it is scraping already.

You can lean off the inside of a roadracing bike because there is more traction available and the tires aren't sliding in the turns.
Think of it like this, lets say you are just flying around your favorite turn leading the race on cloud 9 when all of a sudden you hit a big ol water patch on the track! Oh no!!! The bike WILL fall down into a lowside. Why??? Not because there is water on the ground but because are going too fast for conditions! If you knew the oil patch was there and the races kept going with water on the ground or not. You wouldn't be hanging off in that spot of water like you do in the dry because there is less traction available to use.
No picture in that spot of water riding it like a dirt bike. #1 You would be going slower since there is less traction. #2 Your weight will be over the tires. #3 If and when it does slide you won't fall towards the inside. The whole bike will drift towards the outside of the turn until it scrubs offs speed to regain traction and pull it back towards the inside. Ya get my drift?

I'm pretty sure this post will start up some more replies. I honestly have a complete understanding as to how and why riding styles are a certain way. I have been riding bikes for 26 yrs now and I'm 29 years old. I have been racing for 25 years of which the last 12 have been roadracing and I am an accomplished AMA Pro Racer.
I haven't been on here in about a year and I saw this post and decieded this is something I know about so I decided to write up something on it.
I haven't re read this post so I might have left some things out. Please reply to this post and let me know your thoughts or questions.
There have been so many questions on this topic and I want to help anyone who is asking for advice.

Great to be back,
Jason Farrell
Speed Tech Motorsports
AKA 2 Wheel Authority
(920) 236-0000

[J Farrell / Speed Tech Motorsp]

D*mn,
I need to write a book on this. There isn't enough time for me to completely explain this! I think if I ever get enough time I'll write something about the topic with pictures and stuff and post i on my site.
 ;)
Jason Farrell

[Super Dave]

Start writin', Jason.

I understand what you're saying.

Now, here's your task... ;D

Explain why motard racers generally are riding in "dirt track" style while they have the traction of road race tires on asphalt.

Yeah, they can't ride the same way in the dirt section...too fast for conditions...but...

I'm just a big baiter in this thread... ;D

[J Farrell / Speed Tech Motorsp]

Ohh boy this is where I turn into a computer geek and get nothing done at work!!!  :o Hey who says you can't have any fun right!

Well that all has to do with center of gravity / traction available. When on dirt the bike has less traction so the weight needs to be over the tires because the bike is sliding.
When on asphalt where there is more traction, the rider has to lean in towards the inside because there is more traction available and there are more g forces pulling your body toward the outside of the bike which makes you want to fly off the bike so you have to lean towards the inside.
So basically put: on dirt you have less g-forces pulling you the rider towards the outside of the turn which also plays and effect along with center of gravity & available traction.
 :P
How's it going Dave?
Long time no see.
Jason

[J Farrell / Speed Tech Motorsp]

I guess I didn't explain your question after I reread it. Throw in the fact that a Dirt bike is taller and the center of gravity is higher on a dirtbike (or futher away from the tires towards the inside while leaned over) so there is less weight over the tires which in turn would make the bike fall to the inside and lowside.
 :D

[J Farrell / Speed Tech Motorsp]

Boy oh boy I better get back to work and get on the dyno. I've got motors to build!!!  :)

[J Farrell / Speed Tech Motorsp]

Hey Dave,
What does it take to be an expert around here on this thread? I just can't take this newbie status!!!!! ??? ;D

[Super Dave]

LOL, you've got to be a post wh0re...

[Super Dave]

I guess I didn't explain your question after I reread it. Throw in the fact that a Dirt bike is taller and the center of gravity is higher on a dirtbike (or futher away from the tires towards the inside while leaned over) so there is less weight over the tires which in turn would make the bike fall to the inside and lowside.
 :D

This is a good topic.  

I'm just gonna take you away from the dyno more...LOL!

Ok, yeah, a dirt bike has a CG that is higher than a road racer.

But, when you set up a street bike for road racing, almost generally, it gets set up so that its CG gets set up higher than stock...longer shock, different tires, fork mods, etc.

But now we add a rider on to the whole thing which changes the combined CG.  

You can't race a dirt tracker riding it in the manner that some ride a road racer.  And, then again, you don't ride a dirt tracker like a speedway bike either.  You want and need the dirt tracker to get as much traction as possible for the fastest laps.

So, back to motard, high traction tires, high CG of the dirt bike, ride in a way that the combined CG is like that of a dirt track style, low traction.

Some road race in the rain in more of a ditr track fashion, low traction, others don't...

[J Farrell / Speed Tech Motorsp]

I was waiting for you to talk about rain riding!!!!!!!!! >:( ;D
Alright now senerio rain riding:
Rain Riding is a tough one to explain.
Now baseline is optimum traction adhesion in the dry with your smoking gun fastest lap times ever. Now we throw in the water to play with!!
There is obviously less traction in the wet than say in the dry.

Here let me first start off by giving you an example of what happened to me when I first had to ride in the rain ever on a race bike. First I was freaked out to say the least. This is back in 1995 on a FZR 400 at Blackhawk Farms. Amatuer Lightweight Supersport race my second weekend ever. I had never raced in the rain and my only practice ever was 2 laps in the rain the weekend before. Well I only made 2 laps... I crashed coming out of the bus stop going to the left when the rear tire spun out and I lowsided. I didn't know and FZR400 had the power to spin the rear tire even in the dry!!!! ;D
Well race time is coming up and I decided to go back to my roots and ride the thing like I only knew and that was to ride it like a dirt bike. I don't care what anyone thinks of me I going to do it. So starting on the last row I pass everyone to take the lead on the first lap. Well I rode the bike with my foot down around every single corner sliding the thing everywhere. I can still recall spinning the rear tire all the way through turn 5 with the foot on the ground.  :o(That was actually one of my funnest rain rides ever.  ;D)
Well I ended up lapping all the way back past 4th position. Riders wanted to protest my finish stating that you couldn't ride with your foot down while racing. I called them crybabys and took my trophy.
Why can't I do that anymore???  ;D

Well the safe feeling of me keeping my foot down the whole time was nice and I didn't care if the rear stepped out because I could control it with my foot. It's kind of like your knee being on the ground. But the problem is you can't get your knee down most of the time. And when you do it's so brief and light that you can't keep any weight on it if you lose the rear or front, you'll still lowside.
So they change the profiles on the rain tires to keep more tire on the rode when your leaned over but you can only lean over so far.
I don't ride like that now because the speeds are higher? and I just don't have that attitude I used to have when I was a kid. I would like to try putting my foot down again on a practice day. There is a fine line of traction in the wet of knowing how far to push it before you push it too much. So adding speed takes very small increments of changes from the previous lap. Riders are usually getting faster when they race in the wet because they are developing that feel throughout the race.

So you ride dirtbike style in the wet you better put your foot down. If you ride hanging way off to the inside with your knee out it will work good because when the rear tire slips under acceleration and your hanging way off the inside, if it goes to highside you won't get thrown over the bike. You will basically land on the bike. If you sit straight up and down like most riders, when it steps out you will most likely get thrown over the highside. Bye bye!!!  :-/
The rain tires are now made with narrow side walls and more tire on the road to achieve more traction. If you lean past that angle you will now just have less tire on the road. So I believe since they make the tires with that profile you will have to hang off like a monkey to get the bike to handle better in the rain.
Gotta get back to work!!! :P
Finish it later

[Super Dave]

Rain...

Ok, a bike highsides because the CG of the bike moves out of its spot where it can be controlled.

Often a person's will intuitively move their body inside of the bike to attempt to counter the bike's CG with their body to move the combined CG in an attempt to control it.

Unfortunately, that is usually done too late... ;D

[x2468]

on dirt you weigh the outside peg to slide. if you lean in and slide you will low side. If you want to slide you street bike out of a turn weight the outside peg like u see in the dirt pictures and give it a fist full of gas and steer with the rear. thats what i read, so its theoretically speaking. probably harder than that.