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Coach Question - Front Tire Slide


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Coaches,

 

Corner Question:

Level-4 Rider, purchased Aprilia Tuono Factory few weeks ago, on Hwy-1 (across Golden Gate Bride) riding today (temp about 55 degrees, roads dry but cool) on two occasions I sensed the front tire pushing out a little on agressive turning. Had bike leaned over when conditions were dry, and no cliffs and had no sliding front tire, but did happen twice out of maybe 500 turns.

 

1) Maybe I was a little late on throttle, loaded the front tire when mid-turn.

2) Maybe my weight wasn't up on the tank enough, have caught my self a couple times a little back in seat, maybe 1-2 inches from tank.

3) Maybe I am imaging things.

 

Your thoughts?

 

Greg

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Gday Greg, there are a fair few potentials here, let's make a start: can I ask you to best describe the pressure sequence on the bars when steering the bike into a turn?

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Gday Greg, there are a fair few potentials here, let's make a start: can I ask you to best describe the pressure sequence on the bars when steering the bike into a turn?

 

Jason has already asked a question, but let's get some data on when you thought it slid: turned the bike and it slid right away? Were you still holding onto the bards? Turned and then slid later in the turn? What kind of tires? Had you cracked the throttle on yet? Riding by yourself I assume? Did the road appear clean? Were they any damp patches? What time of the day?

 

This might shortcut the process a bit, get some more data up.

 

CF

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Jason,

My input on the bars was consistant I believe, was hanging off and had my pre-turn set up initiated prior to quick-turn.

 

 

Cobie,

 

--Turned the bike then mid-turn felt a little slide, hands were on the bars, knee to tank and hanging off prior to starting turn, grip was medium on the bars after pushing bars to start the turn.

--If I remember correctly I just started throttle roll on just before mid-turn and felt the front slide.

--The tires are Pirelli Rossa Corsa, tire wear is even with about 25% of tread left.

--Road was dry, about 1pm, 55-60-degrees, no debris, I think one turn was left the other was right,

 

Hope this helps, I did catch myself about 1-2 inches from the tank on a couple of instances, maybe I needed to be up on the tank more with these two turns? Speed was maybe 30mph to 40mph.

 

Thanks - Greg

 

 

 

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Cool Greg, thanks for the fast response, I was away though so glad Cobie got the ball rolling on the other good data.

 

I need some clarification on your statement in reply to the pressure on the bars AFTER steering, but to avoid some back and fourth I'll make an assumption: You've stated the pressure on the bars was "constant", (read this next bit carefully) can I assume this means we have some pressure on the bars to "hold the bike in the turn" AFTER we've finished steering?

 

Would you believe me if I said we don't need to hold a bike into the turn after steering? I.e. Once we've steered the bike, we should relax the pressure on the bars as soon as possible. So the pressure sequence to steer a bike is best described as "Press, then release". The bike will maintain its lean until you tell it to do otherwise (via a new steering input).

 

Why would we want to do that? That's a whole sessions worth of great information which is best presented in person at a school day, but instead of going through all that, how about we try something so you can make your own decision on whether this works or not.

 

So let's give something a shot on your next road ride, on a easy road where you have little or no distractions (track is best), steer the bike to your desired lean angle, then, release the pressure on the bars. So long as you are not slowing down (i.e. doing a even, smooth and progressive throttle roll-on) your bike will maintain it's lean angle!

 

Write back once you've given this a try and we'll give you the info you need to understand why the slide occurred, sound good?

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Ok rode today, just north of Infineon Raceway. 65-70 degrees.

 

I think the issue is the front shocks, the Tuono has fully adjustable Ohlins. Suspension at factory/stock setting, front end is a little too soft/mushy. Aprilia forum states specs for aggresive riding, track riding, which are far from where the bike is today.

 

Out of 300 miles of twisties, and altitude gain of 3,000 ft, the front tire faded only once.......a little on a right hander sweeper at about 70mph. Followed level-4 protocol's ie, left knee to tank, hips, shoulders open to turn, was more up on tank, dropped right elbo to allow body weight to drop inside of bike, light on the grips, bike was leaned over, applied throttle roll-on, all fine.......at end of turn after into 60% of turn felt the front tire slip or (melt) felt more like it. I picked up the bike a bit, and I felt the tire plant a little better..........I wasn't leaned over that far, maybe knee 3-4 inches from pavement.

 

We have local guy who was one of the top Factory Honda mechanics that worked on suspensions, I'll have him look at the bike. He has a big questionaire I need to fill out, then we'll discuss before I bring to him.

 

Your thoughts?

 

Greg

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Greg,

 

Jumped in on this late, wondering if you are adding a little lean angle and throttle at the same time?

 

CF

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I believe I may have identified the problem............I have fully adjustable ohlins, front fork felt a little mushy as I mentioned earlier.

 

I contacted James Siddall/Super Plush Suspension in San Francisco, see www.superplushsuspension.com James has worked with the Honda Factory Team, said I have more than likely exceeded the pre-set factory suspension settings. With the front end loosing traction as I gain more speed, the tire patch has reached it's max for the current suspension set up. ( I can only give detail in layman terms, he was speaking a different language)

 

Filled out rider form on his website, and now scheduling appointment to have him turn the suspension..............will keep you posted as to what he said and what we did.

The aprilia forum thru AF-1 Racing in Texas has a number of Tuono Factory Race Settings that others around the globe have done with the onlins. Will do my research before seeing James next week.

 

Greg

 

 

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Cobie, Jason,

 

Visited James Siddall/Superplush Suspension today, by-the-way he said to say hi, I think he is done some work for you and Kieth.

My suspension was really off, by a long shot, without typing "war & peace" hear are brief details.

 

After Before

Front Pre-load 8-Out 8-Out

Front Rebound 11-Out 10 on one fork, 17 on other

Front Compression 10-Out 7-Out

Rear Pre-load 9-Out 8-Out

Rear Rebound - 26 16

Rear Compression -12 11

 

Front Ride Height - 8mm 4mm

Rear Ride Height - 4mm 4mm

 

Front end now turns much better, feels rock solid, now will test.

 

Greg

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Good stuff Greg, keep on testing, if you're 100% that the problem is suspension and not one of those things we do to upset the bike in motion then I'll bow out, there are much wiser suspension techs than I. A good source of suspension is the "independent suspension forum". Made up of a few suspension gurus worldwide.

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Front Rebound 11-Out 10 on one fork, 17 on other

 

 

Wow.... just this one maladjusted setting is enough to make the bike handle poorly.

 

On a side note, I like a working suspension. B)

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James S. has been around a long time, i didn't know he had his own shop, I had known him from the AMA circuit.

 

CF

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Cobie,

 

James said to say hello to you and Keith, he worked on one of your bikes in the past is that correct? He's located behind the Giants Stadium in Mission Bay Area, San Francisco.

 

Two more months to April 4-5, can't wait.............Bill Young and 4-5 of our friends will be there.

 

Greg

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Oh no, not Bill Young and cronies!!!! :huh:

 

OK, I admit, I like having you guys around, keep us on our toes.

 

James worked on a few race teams, and way back when on one of the 250's, think that was where I first met him.

 

CF

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Greg, just a side note, keep in mind when working forks, the individual legs can be on different settings no problem, as once they're bolted together into the triples they work as a single unit. I.e. you can put a .95 spring in one and a .90 spring into the other, even have rebound clicked 6 out on one leg and say, 2 out on another... the spring and rebound in this instance will work as a concatenation of the two settings, like having a 0.925 spring and a rebound setting of 4 out.

 

So if this was the problem, it wouldnt be that the two are different, it's that the two are adding up to an incorrect setting for you on your equipment at your laptime band.

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Thanks Jason, the overall new set up is brilliant!!! glad we made the change, there is so much to learn, unreal.

 

Cobie, As for the cronies, yeah, a bunch of old guys now doubt, but we like to have fun and we enjoy the coaches too......inside we're all very competitive, so when we go to Code Race again in October I want to make sure we're separated, don't want the other guys to know what I'm working on. (Bill crashing wasn't my fault......Will gave me a look.....I said it wasn't me, I was on the other side of the track, Will said "we have to keep you guys separated" kidding of course) Next Code Race we will have four of us, that will be really fun.

 

Pete, good to hear from you, see you in two months.

 

Greg

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