Why do dirt trackers and ice racers lean the bike down and keep the riders upright - where road racers (excluding motard) lean over to help the bike stay more upright?
Why do the ice racers and motards use riser bars? Aren't those better suited for control on jumps and bumps? Could an ice racer benefit from lower clipons?
Basically - why is there such a difference in style between an ice racer going around a corner and a road racer?
Haven't ever you tried riding a street bike off-road and with a few jumps? ;D
It's far easier to use my DR650 for that.
A lot of has to do with leverage. It's also a lot easier to deal with the inevitable sliding.
This year I've done a few roadraces on my DR650. Up to now I've have been using the OEM Bridgestone Trailwings which are fairly knobby. I consistently went 4 seconds per lap faster when I rode it like a dirtbike. I will be trying out some BT45s next and will re-evalute how I ride it.
First, dirt bikes and motard bikes have more ground clearance than do street/roadrace bikes. By leaning the bike and the rider more upright requires more clearance. By the rider moving to the inside, the bike has to be leaned less than if the rider didn't.
The biggest differences between dirt and road is traction and the size of the bumps. Offroad it is much easier to control the bike by staying upright and leaning the bike. In higher speed offroad cornering, the rider tends to lean with the bike or actually move their upper body towards the inside of the corner (especially if there is a fairly large berm). In dirt track and ice riding (flat, slick corners), it is easier to control the sliding of the bike by sitting more vertical.
As far as the bars, in off road riding, the rider needs to be able to move forward and backward more than a roadracer. Higher bars make this far easier than would clipons.
I have seen motard riders do it like dirt trackers or roadracers (I have seen pictures of Nicky Haden dragging his knee on a motard bike). It may be more of a function of what the rider is used to, especially dirt trackers.
Road Race and Off Road tracks have very different properties from a physics point of view, so tire manufacturers make different tires for dirt and for road.
With Road Racing, the track is a solid, immovable object that the tires work with...
With Motocross/Supercross etc. the track is a fluid, moveable object that the tires work with...
That said, the tire manufacturers have designed tires to take advantage of the surface...
Dirt tires (mx/sx) have larger knobbies on the sides to take advantage of the more fluid/moveable track... i.e. digging the bike in results in MORE traction as the knobbies can be larger and pull the bike more...
For Road Race tires traction is rubber vs asphalt.... and knobbies wouldn't help because they provide a smaller surface contact area (if you road raced knobbies you'd low side out sooner than DOT's... and that's why slicks have more traction than DOT's... more SURFACE contact area).... on the track traction is a funtion of chemistry rather than physical shape (rubber bonding to the track rather than a knob moving dirt).
Dirt and track are very different beasts... but riding in the dirt sure seems to help riding on the track.
The upshot is that in the dirt... digging the bike in (with knobbies) results in MORE traction... and on the road race track.... hanging off and keeping the bike more upright results in MORE traction (and less tire wear).
8)
QuoteWith Road Racing, the track is a solid, immovable object that the tires work with...
With Motocross/Supercross etc. the track is a fluid, moveable object that the tires work with...
That doesn't explain why motard racers, with a whole lot of asphalt that is solid and immovable, aren't riding like road racers.
I've been doing a little dirt track racing lately and it's alot easier to slid the back end of the bike around sitting on the opposite side of the seat than the way you are turning.
Example: Going around the dirt track (You know, go straight, turn left) turning left your butt is on the right side of the seat.
This was hard to figure out at first because I'm more used to road racing.
It's a wonderful feeling sliding the a$$ end of a motorcycle around a race track. I love it!
TT racing is fun to, you actually get to turn right!
STEVENACERACING.COM (AMA Sanctioned Events)
Brian is the Physics proffesor, so take his explanation of why you do what to make the bike do this and why why why why....
Crap I don't know, I just do this and the bike does that. That's good enough for me!
Dirt track (not MX or SX I suck at those two) is different. You steer with the throttle and counter steer with the bars. Want to turn more..give it more gas. You need leverage for this, not a selling point for clip ons Also your pegs need to be low and centered again so you can adjust traction between the front and the rear wheel making clipons uncomforatable. Since most dirt trackers don't have front brakes (at one time no brakes were allowed) if you nail the rear brake you just go straight on dirt so you have to wiggle the front bars to get the back to pitch out or use body english or engine pull to get the back to go out thus being set up for the corners. This helps you deselerate into the corner and puts you in a position to accerate hard out of the corner. Folding the inside peg is very common.
QuoteThat doesn't explain why motard racers, with a whole lot of asphalt that is solid and immovable, aren't riding like road racers.
Original question was...
Why do dirt trackers and ice racers lean the bike down and keep the riders upright - where road racers (excluding motard) lean over to help the bike stay more upright?
Excluding motards...
And my answer was from Gaetano Cocco.
(hey, I'm not smart, I just know who to ask).
QuoteThat doesn't explain why motard racers, with a whole lot of asphalt that is solid and immovable, aren't riding like road racers.
My understanding is they are sliding the bike to preserve the suspension geometry. When you lower a bike too far (like going from a 21" wheel to a 17") you lose a ton of trail.
If the rear is sliding the front isn't compressing so much, preserving trail.
Of course, we are working on a solution for this.
I'm learnin' ;D
Dave, call the shop sometime. x133
Hey, Andy...
Yeah, I've always thought of that.
Some people seem to like 19's at some local stuff...so I've heard. But it's not common in top level motard for anyone to have 19's.
Slowing down a bike in motard with the back hung out would allow the chassis to maintain an amount of trail that it would otherwise not have when leaned over lined up.
Probably so they can run motard and dirttrack with the same bike.
Although the record up Pikes Peak this year (all dirt) was set on a KTM motard with 17" rains.
Now was that a motard bike that came with 17" tires OEM?
In 1987, we raced a GSXR1100 Superbike in endurance. We thought we'd be cool and get a 17" front PM wheel to reduce mass etc.
Really turned very, very different from a regular GSXR with 18's front and rear, obviously. But we could get better slicks for endurance racing.
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
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
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
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
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
Boy oh boy I better get back to work and get on the dyno. I've got motors to build!!! :)
Hey Dave,
What does it take to be an expert around here on this thread? I just can't take this newbie status!!!!! ??? ;D
LOL, you've got to be a post wh0re...
QuoteI 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...
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
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
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.
It is.
Ok... heres a question... Might sound dumb but here goes...
My first track day at MAM I high sided my zx6rr in the last turn (T14?). It happened so fast I thought I had low sided. After I picked myself up I realised I had gone farther than my bike. So I was like WTF?! How did I pass my bike if it weighs more? Then they told me I high sided. Pretty spectacular photos if you haven't seen them already, lol.
So the last day I was at the track this season I feel the back end slide WAY out coming through that same corner. I just ride it out and make it just fine leaving a nice big black mark.
Now I realise there were different certumstances... I was a bit more skilled than my first track day but I didn't think enough to be able to drive through a slide like that. I also had brand new Bridgestone 002's on the first track day and the last one I had 002's on that had 3 track days on them and were worn down to the ware marks on the sides. The first track day was before I had the PC tuned to have a smoother power dilivery on the roll on, and it was also before I spent 2 days with Dave tuning the suspention.
Now... my question... Why could I feel the rear slide out and ride it out, avoiding a high side, the 2nd time and the first time I was thrown off before I even knew what happened?
Is it because the set up? Is it the way the worn tire was gripping or not gripping?
Having had experience with your set up, yeah, that's going to be part of feel.
When anything happens, it's going to take you a moment to recognize that something is happening, then you've got to decide what you're going to do, then do it.
Given that your previous set up didn't have "a lot of feel", your chassis was way out of shape when you started to realize that things weren't right. By then, the CG of the bike past a point where it could not be pulled back into alignment to keep it upright.
Your new chassis set up supported you better, and it offered feel. So, your recognition of something going wrong was just a bit sooner where you could stay in control.
Certainly, a little experience for you can help over come some of the sensory overload that you had the first time our. Can help your reaction times being a little familiar with things.
One can still beg a set up issue:
If your surrent set up supports you on worn tires with the spring rate you have....
When you add the extra traction of a good new tire, the chassis can get loaded more...
Sp, do you really have the correct spring rate for your set up?
QuoteNow... my question... Why could I feel the rear slide out and ride it out, avoiding a high side, the 2nd time and the first time I was thrown off before I even knew what happened?
Is it because the set up? Is it the way the worn tire was gripping or not gripping?
LOL!!!! I'd say you got Lucky....
QuoteFirst, dirt bikes and motard bikes have more ground clearance than do street/roadrace bikes. By leaning the bike and the rider more upright requires more clearance. By the rider moving to the inside, the bike has to be leaned less than if the rider didn't.
You'd be suprised how little ground clearance a motard bike has. The pegs drag almost instantly. and if you hit a bump mid corner it's nothing to drag the frame.
If you look at one on a stand they seem super tall, but once you get all that suspension compressed in a corner they start dragging parts real fast.
QuoteNow... my question... Why could I feel the rear slide out and ride it out, avoiding a high side, the 2nd time and the first time I was thrown off before I even knew what happened?
Is it because the set up? Is it the way the worn tire was gripping or not gripping?
A highside happens when the rear tire comes out far enough to go past the steering lock. If you could turn your front wheel 90 degrees to the rear wheel, you'd never highside. That's why dirt trackers always lowside when they go down. They have a ton of lock to lock travel.
The second time you probably just reacted faster or the tire didn't step out far enough.
Your first crash may have been rider interference too. Most of the time if a rider crashes and has no idea why, he was riding over his head...
QuoteA highside happens when the rear tire comes out far enough to go past the steering lock.
No, it isn't. Re think it.
You can put the bike to the steering lock and go down on the low side.
QuoteNo, it isn't. Re think it.
You can put the bike to the steering lock and go down on the low side.
True, there are other variables, I'm just saying that as long as the front wheel is pointing straight, you won't highside. You might get kicked out of the seat, but the bike won't highside.
It's all reated to where the bike's cg is at and traction.
Riders usually highside way before the bike ever reaches the locks.