Bike Nearly slipped from under me

Heffdan · August 14th, 2012, 07:54 PM

So Today on my way to work I came around what's best described as a "sharp turn left" thats angled downwards coming off a little bridge. It merges into a school zone so I was going especially slow - Well less than 30km/h. Anyway as I came around on a left lean - Not a ridiculous angle though just enough to go around the bend, the bike just slid from underneath me. As a immediate reaction I straightened the steering and by instinct used my left leg/foot too stop myself from going further and low siding.

Tyres were warm - had travelled about 20k's before the bend,
Running OEM tyres though with 2,200km's on them. I have been a total noob and not checked my PSI/pumped the tyres yet (Going to do that straight away after work now) but I would figure they would if anything have a Lower psi which would mean they would be "flatter" Which means more traction if anything? (obviously still not good compared to proper psi)

Any thoughts would be appreciated - Hurt my ego towards "flicking the bike" even in proper conditions.

TL;dr version - Went around downhill corner slow speed, bike slipped, used leg to stop, Worried about bike slipping now,

Panda · August 14th, 2012, 07:57 PM

Gravel, oil, sand? Anything on the road?

Jiggles · August 14th, 2012, 08:01 PM

Yea its not the tires that caused this but something that was on the roadway.

Heffdan · August 14th, 2012, 08:29 PM

Going to investigate on the way home - the angle is a real pain its literally hard to "watch the road" as such when trying to look ahead of the turn

Alex · August 14th, 2012, 08:34 PM

What did you find your tire pressure to be?

Heffdan · August 14th, 2012, 08:44 PM

Not sure - Time zone here is 1:45pm, I am still "working" :P will defiantly post results though.

lgk · August 14th, 2012, 08:52 PM

did you pull the clutch?

Heffdan · August 14th, 2012, 09:36 PM

No - maintained normal throttle acceleration through turn

lgk · August 14th, 2012, 09:43 PM

how steep is the down hill grade?

Heffdan · August 14th, 2012, 10:07 PM

its a awkward one to explain - the corner is sharp and pretty steep but its only a short bend.

Motofool · August 15th, 2012, 09:31 AM

Quote:

Originally Posted by Heffdan

........ the bike just slid from underneath me.......,

Do you know what tire?

If the front tire, it is possible that the downhill and the transfer bridge-pavement unloaded the tire enough as to reduce friction or traction.

A quick flick imposes some extra load to the front tire; in order to perform, the tire needs to be loaded.

I learned that one the day that I tried a quick flick while the bike was accelerating hard: a no-no.

Lychee · August 15th, 2012, 10:08 AM

Quote:

Originally Posted by Motofool

Do you know what tire?

If the front tire, it is possible that the downhill and the transfer bridge-pavement unloaded the tire enough as to reduce friction or traction.

A quick flick imposes some extra load to the front tire; in order to perform, the tire needs to be loaded.

I learned that one the day that I tried a quick flick while the bike was accelerating hard: a no-no.

Did you mean "the tire needs to be unloaded"?
If not, why does it need to be loaded?

Motofool · August 15th, 2012, 12:07 PM

Because friction force is directly proportional to the force that is normal or perpendicular to the surfaces in contact.

http://www.engineeringtoolbox.com/fr...nts-d_778.html

The more (vertical) weight over a tire, the more (horizontal) traction it is capable of.

flynjay · August 15th, 2012, 12:45 PM

I had a similar expirence on the turn to my street. Typical suburb four lanes divided by median turning onto single lane. One day there was construction closing the inside lane which forced me to go a little wider than usual. At mid-corner the tire slips about 3", which almost caused me to lowside. Luckly being light on the bars, the bike corrected itself enough not to tuck under.

Go back and look there was a 1" diameter spot of dirt that I just happened to run over mid corner.

Heffdan · August 16th, 2012, 04:00 PM

Had a look and couldn't find anything significant enough to explain the slip.

After checking my tyres though found my front was at 26 psi and the rear was at 27. Dayum..

Even though I don't think that would have caused the slip remember to check your psi weekly guys!

August 14th, 2012, 07:54 PM	#1
Heffdan ninjette.org member Name: Dan Location: Gods Country - Australia Join Date: May 2012 Motorcycle(s): 2012 Ninja 250 SE Posts: 42	Bike Nearly slipped from under me So Today on my way to work I came around what's best described as a "sharp turn left" thats angled downwards coming off a little bridge. It merges into a school zone so I was going especially slow - Well less than 30km/h. Anyway as I came around on a left lean - Not a ridiculous angle though just enough to go around the bend, the bike just slid from underneath me. As a immediate reaction I straightened the steering and by instinct used my left leg/foot too stop myself from going further and low siding. Tyres were warm - had travelled about 20k's before the bend, Running OEM tyres though with 2,200km's on them. I have been a total noob and not checked my PSI/pumped the tyres yet (Going to do that straight away after work now) but I would figure they would if anything have a Lower psi which would mean they would be "flatter" Which means more traction if anything? (obviously still not good compared to proper psi) Any thoughts would be appreciated - Hurt my ego towards "flicking the bike" even in proper conditions. TL;dr version - Went around downhill corner slow speed, bike slipped, used leg to stop, Worried about bike slipping now,

August 14th, 2012, 08:01 PM	#3
Jiggles Jigglin' your Jiglets Name: Sean Location: San Jose, Ca Join Date: Jun 2011 Motorcycle(s): 2009 K1300S, 2013 Ninja 300, 2011 Ninja 250R, Faster than Unregistered's ninjette Posts: Too much. Blog Entries: 1 MOTM - Apr '13	Yea its not the tires that caused this but something that was on the roadway. __________________________________________________ If the Ninja 250 doesn't have enough power for you, then you don't know how to ride it. AFM #676 Supersports are for n00bs

August 14th, 2012, 08:34 PM	#5
Alex ninjette.org dude Name: 1 guess :-) Location: SF Bay Area Join Date: Jun 2008 Motorcycle(s): '13 Ninja 300 (white, the fastest color!), '13 R1200RT, '14 CRF250L, '12 TT-R125LE Posts: Too much. Blog Entries: 7	What did you find your tire pressure to be? __________________________________________________ Montgomery Street Motorcycle Club / cal24.com / crf250l.org / ninjette.org ninjette.org Terms of Service Shopping for motorcycle parts or equipment? Come here first. The friendliest Ninja 250R/300/400 forum on the internet! (especially Unregistered)

August 15th, 2012, 12:07 PM	#13
Motofool Daily Ninjette rider Name: Hernan Location: Florida Join Date: Mar 2011 Motorcycle(s): 2007 Ninja 250 Posts: A lot. MOTY - 2016, MOTM - Dec '12, Jan '14, Jan '15, May '16	Because friction force is directly proportional to the force that is normal or perpendicular to the surfaces in contact. http://www.engineeringtoolbox.com/fr...nts-d_778.html The more (vertical) weight over a tire, the more (horizontal) traction it is capable of. __________________________________________________ *Motofool* *.................................Never ride faster than your guardian angel can fly* "Mankind is composed of two sorts of men — those who love and create, and those who hate and destroy. Love is the bond between men, the way to teach and the center of the world." - José Martí

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August 14th, 2012, 07:57 PM	#2
Panda not an actual panda Name: dan Location: philadelphia Join Date: Aug 2012 Motorcycle(s): 2008 Ninja 250, 2009 CBR600RR (Sold) Posts: A lot.	Gravel, oil, sand? Anything on the road?

August 14th, 2012, 08:29 PM	#4
Heffdan ninjette.org member Name: Dan Location: Gods Country - Australia Join Date: May 2012 Motorcycle(s): 2012 Ninja 250 SE Posts: 42	Going to investigate on the way home - the angle is a real pain its literally hard to "watch the road" as such when trying to look ahead of the turn

August 14th, 2012, 08:44 PM	#6
Heffdan ninjette.org member Name: Dan Location: Gods Country - Australia Join Date: May 2012 Motorcycle(s): 2012 Ninja 250 SE Posts: 42	Not sure - Time zone here is 1:45pm, I am still "working" :P will defiantly post results though.

August 14th, 2012, 08:52 PM	#7
lgk ninjette.org certified postwhore Name: Jason Location: Norfolk, VA Join Date: Dec 2011 Motorcycle(s): 2012 EX250, 2014 EX300 Posts: A lot.	did you pull the clutch?

August 14th, 2012, 09:36 PM	#8
Heffdan ninjette.org member Name: Dan Location: Gods Country - Australia Join Date: May 2012 Motorcycle(s): 2012 Ninja 250 SE Posts: 42	No - maintained normal throttle acceleration through turn

August 14th, 2012, 09:43 PM	#9
lgk ninjette.org certified postwhore Name: Jason Location: Norfolk, VA Join Date: Dec 2011 Motorcycle(s): 2012 EX250, 2014 EX300 Posts: A lot.	how steep is the down hill grade?

August 14th, 2012, 10:07 PM	#10
Heffdan ninjette.org member Name: Dan Location: Gods Country - Australia Join Date: May 2012 Motorcycle(s): 2012 Ninja 250 SE Posts: 42	its a awkward one to explain - the corner is sharp and pretty steep but its only a short bend.

August 15th, 2012, 12:45 PM	#14
flynjay ninjette.org guru Name: Jason Location: Houston, TX Join Date: Nov 2011 Motorcycle(s): 2007 Ninja 250 (sold), '06 Ninja 650R Posts: 455	I had a similar expirence on the turn to my street. Typical suburb four lanes divided by median turning onto single lane. One day there was construction closing the inside lane which forced me to go a little wider than usual. At mid-corner the tire slips about 3", which almost caused me to lowside. Luckly being light on the bars, the bike corrected itself enough not to tuck under. Go back and look there was a 1" diameter spot of dirt that I just happened to run over mid corner.

August 16th, 2012, 04:00 PM	#15
Heffdan ninjette.org member Name: Dan Location: Gods Country - Australia Join Date: May 2012 Motorcycle(s): 2012 Ninja 250 SE Posts: 42	Had a look and couldn't find anything significant enough to explain the slip. After checking my tyres though found my front was at 26 psi and the rear was at 27. Dayum.. Even though I don't think that would have caused the slip remember to check your psi weekly guys!