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Have You Ever Slid The Front Without ...


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#21 Jaybird180

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Posted 01 May 2012 - 04:29 PM

It seems tire manufacturers have an opposing Point of View on the subject. Personally, I'd like to see more data.

I have once experienced the "fun" of pushing the front tire beyond the limit of traction. It slid a few feet (or milimteters ?) gripped and steered me into the corner. It happened so quickly...scared me at the time, but now I miss that level of intensitey in my riding.

#22 mugget

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Posted 02 May 2012 - 03:13 AM

Hey Jaybird, your comment caught my attention with the way you describe pushing beyond the limit of traction... from what you describe there, it seems like you actually found the limit of that particular road surface, not the limit of the tyre. Posted Image On a good clean surface, with good tyres that are up to working temperature - if you turn quickly enough into a corner the rear tyre will actually slide before the front does. (Of course it's still possible to slide the front well before this if the rider makes a mistake such as locking the front wheel or making additional steering inputs.)

#23 Eirik

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Posted 02 May 2012 - 06:36 AM

Mugget, here is my experience on the front vs. rear issue:

My brother and I used to ride completely differently, but with the same pace. By different I mean that when I was leading on the road I would still be braking when my brother wanted to be hard on the throttle, and when my brother was leading he would be on the brakes when I still wanted to keep the throttle pinned for several seconds. My brother would also shift his weight inboard a bit (1/4 cheek off and head towards inner mirror).

According to the book, my brother was doing it right and I weren't. However, he experienc(ed) lots of front end slides and usually his front tyres wear out before the rear. I, OTOH, virtually never had any front end issues (unless I dug in hard parts heavily enough to unload the tyres) despite braking to the apex - and sometimes beyond. I also generally see the front tyre last 1.5 times that of a rear tyre.

Now. As of the past few years, I have changed my way of riding to something closer to what my brother does, that is braking earlier and getting on the throttle (usually fairly gently) earlier. And find that the front will let go before the rear. It's even more noticeable in the wet. When I used to turn on the brakes, the front felt secure and it was easy to know what was going on between the rubber and tarmac. The way I ride now, using gentle acceleration through most of the turn and turning in with the brakes either off or nearly off I lack the communication with the tyre and also grip seems reduced quite a bit.


Eirik

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#24 Cobie Fair

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Posted 02 May 2012 - 05:03 PM

Now. As of the past few years, I have changed my way of riding to something closer to what my brother does, that is braking earlier and getting on the throttle (usually fairly gently) earlier. And find that the front will let go before the rear. It's even more noticeable in the wet. When I used to turn on the brakes, the front felt secure and it was easy to know what was going on between the rubber and tarmac. The way I ride now, using gentle acceleration through most of the turn and turning in with the brakes either off or nearly off I lack the communication with the tyre and also grip seems reduced quite a bit.


Eirik,

Something awry here...I'd wonder if you were adding some lean angle at the same time.

CF

#25 Eirik

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Posted 02 May 2012 - 08:50 PM

I've tried to reconstruct the situations in my mind, but I honestly cannot tell. I'll pay attention on my next rides to see if I add lean now that I'm early on the gas. Thanks for the suggestion!

Eirik

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#26 mugget

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Posted 02 May 2012 - 10:16 PM

Interesting that you mention those different riding styles as a reason for the front losing traction before the rear... Looking past the fact that it's more noticeable in the wet (since low traction surfaces are the one situation where it is possible to loose the front purely by steering too quickly), let's consider the example of a racer on a dry track as the 'model example'. Have you ever seen a racer approaching a turn really fast, then as he turns in towards his apex the rear wheel slides to the outside of the corner a little bit? It almost looks as if they were backing in, but they're not. It can be hard for me to spot it on television, but having watched racing in person it really stands out. So under dry conditions on a good surface with good tyres - it's plain to see that the rear tyre will lose traction before the front (if the rider doesn't make unneeded inputs). Add in the fact that the same racers were also using the front brake while they were turning in and the rear was sliding... it just shows what is possible.

So then if one person can quick steer without sliding the front, but another person does slide the front - the person who is sliding must be doing something differently to cause the slide. This could be a number of things. To list some of the more common ones that come to mind:
  • holding on tight to the handlebars
  • making additional steering inputs while in the corner (making more than 1 steering input)
  • adding more lean angle (by making additional steering input)
  • using too much brake (locking the wheel)
  • changing body position (causing instability in the bike)
  • poor throttle control (causing instability in the bike)
If you're 100% positive that you're not doing any of those things, yet the front tyre still slides before the rear - then it must come down to the one final difference, which is the road surface.

You can watch any racing, YouTube videos, etc. and you won't see one single crash caused simply by steering too fast. It will always be due to the road surface, or the rider makes one of those above mentioned riding errors.

#27 Jaybird180

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Posted 02 May 2012 - 11:16 PM

Interesting that you mention those different riding styles as a reason for the front losing traction before the rear... Looking past the fact that it's more noticeable in the wet (since low traction surfaces are the one situation where it is possible to loose the front purely by steering too quickly), let's consider the example of a racer on a dry track as the 'model example'. Have you ever seen a racer approaching a turn really fast, then as he turns in towards his apex the rear wheel slides to the outside of the corner a little bit? It almost looks as if they were backing in, but they're not. It can be hard for me to spot it on television, but having watched racing in person it really stands out. So under dry conditions on a good surface with good tyres - it's plain to see that the rear tyre will lose traction before the front (if the rider doesn't make unneeded inputs). Add in the fact that the same racers were also using the front brake while they were turning in and the rear was sliding... it just shows what is possible.
.

I've seen this rear tire displacement before and was told this is what a counter steer looks like at that point of view when the rider flicks it over quickly.

#28 Eirik

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Posted 03 May 2012 - 07:47 AM

So then if one person can quick steer without sliding the front, but another person does slide the front - the person who is sliding must be doing something differently to cause the slide. This could be a number of things. To list some of the more common ones that come to mind:

  • holding on tight to the handlebars
  • making additional steering inputs while in the corner (making more than 1 steering input)
  • adding more lean angle (by making additional steering input)
  • using too much brake (locking the wheel)
  • changing body position (causing instability in the bike)
  • poor throttle control (causing instability in the bike)
If you're 100% positive that you're not doing any of those things, yet the front tyre still slides before the rear - then it must come down to the one final difference, which is the road surface.



I do not have lack of traction under turn-in, but at maximum lean. There is not much acceleration taking place at this point, but some. The only thing I'm not sure about is whether I continue to lean in a bit extra after applying the throttle or not. I do know that the way I used to ride, I would be braking or on trailing throttle until I stood the bike up and the front end grip was never an issue. The most plausible reason is that I continue to add lean after I apply the throttle.

Eirik

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#29 Jaybird180

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Posted 03 May 2012 - 02:33 PM

Try the steering drill. Setup a video camera and go directly to or away from it and see for yourself.

#30 khp

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Posted 03 May 2012 - 03:19 PM

Back in Ye Olde Days, when I wasn't using tire warmers and I was so slow that I could ride a full season (5-6 days) on a single set of tires, I found that I would slide the front tire in a specific hairpin on the first lap. I did this 2-3 times on the same day, but only on the first lap.

The slide would be very quite small, and (if I remember correctly) happen before the apex, just after getting to full lean. Thinking back to the incidents, I attribute the slides to several factors that I combined: Cold tires (no warmers), worn front tire, poor throttle control (most likely I either had a closed or neutral throttle), and a fairly cool track (maybe 18-20C, it was the last trackday of the season).

So by doing less-than-wise things, yes, you can make the front tire slide on a good dry track. Today I ride 7-8 seconds faster at the same track, with no front-end problems in said hairpin (I've had the rear spin slightly out of the hairpin when being too enthusiastic with the throttle at almost full lean).

Kai

#31 Eirik

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Posted 03 May 2012 - 06:59 PM

Chill may be a factor as it was well under 10C and overcast when it happened. I also think I had some cold tearing on the rear tyre - at least the surface was dimpled and felt like sand paper and I was not riding anything like hard. The rubber smoothed out after riding on a sunny 15C day. And not being a great rider no doubt count for quite a bit. Still strange that it doesn't appear to be a problem when loading the front, though.

Setting a video camera sounds like an idea, though. Would it be best to have it stationary or have a cameraman?

Eirik

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#32 Jaybird180

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Posted 03 May 2012 - 09:24 PM

Set it on the ground and ride away. The angle should be about right.




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