Low siding

J

jeff96

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Did a slow speed low side today which was completely unexpected and I'm still not sure I could have seen it coming.
CBR250 with Michelin street pilot rear tire, stock size with a few hundred kms on it. I've ridden this bike for about 30,000 km but recently I've been riding a GL650 most of the time. I've low sided this bike once: in snow. Today, hot dry roads, had ridden about 50 km before the spill.
Right hand turn at a stop light. The light was green, so coming in at a normal speed, not from a stop.
Mid turn, the rear just slipped out under me. It was a complete surprise. No extreme speed or lean angle. Minor damage to bike and gear.
I walked the intersection after. The older pavement had no sand, but pebbles flush with the pavement offered little friction when I dragged my boot over the surface. Could that be all it was to cause this?
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Likely oil - are you making sure to stay out of the centre of the lane at stop lights?

Could also be paint strips but mid turn more likely oil.....were you braking mid turn at all.?
This kind of heat asphalt is just plain treacherous.

Glad you are okay.
 
Not paint. No visible oil and it was beyond where cars stop and drip. I don't ride in the center of a lane generally.
I do notice coming to a stop sometimes that the asphalt is slippery under my foot, but I can't distinguish the slippery stuff from the good kind visually

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having put 18k on the same tires on a similarly sized bike: Michelin Pilot streets are a very hard tire that definitely sacrifice grip for longevity. That being said they are extremely forgiving - if you end up losing traction they are not very dramatic and unless you cranked the throttle or tried to throw a ton of additional lean angle on them they will hook back up again with minimal rider correction. As much as people hate on them they are a great tire to learn on because of this.

However if these are the original tires that came on the bike they are now 7-8 years old at least. These tires are rock hard when fresh and i'd imagine they would have turned to hockey pucks by now. This would be my initial guess as to why you had the issue - check your date codes to see how old the tires actually are.

Were you maintaining a constant throttle level while taking the corner or did you roll off/on as the bike was leaning? Based on your chicken strip you were approaching sort of the "danger zone" with that tire. I found anytime you lean it past the Michelin man's head would be the point where that tire would slip much more easy. IF you were maintaining a constant throttle (no roll off/on) while leaning in you may have pushed the tire past the traction limit. Consider that as you lean you are changing the gearing of the bike, your motor will naturally spin up faster (increasing torque) while leaning as the diameter of tire decreases at lean compared to vertical:

 
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Inspect tire pressure, wheel, steering head and swing arm bearings, frame cracks, then you pretty much checked everything it could be bike related imho.

Ride all of it ready for it to be slippery. Ya I know easier said then done.
 
Glad to hear you weren't hurt.

You mentioned it was an old road surface, around a right turn in an intersection. I've sometimes found it to be almost polished (for lack of a better word) from all the stopping and turning across that section. My theory (no scientific thinking here, just a guess) is that over time the surface wears, smoothes out and loses some of its "grip". I've felt that slight sidestep from the rear tire a few times in similar situations. I'm wondering if that contributed to the slide.
 
what r3 said
the OEM tires that come stock(especially on low displacement learner bikes) are garbage when they new, because they so hard, the tread doesnt really show signs of wear, and especially on new small displacement learner bikes, guys ride them for a season, and pass it on, rinse and repeat

Wouldnt be surprised if it has those crappy old tires that came stock with the bike

I had to replace a front tire on my recently purchased bike, it passed safety, had lots of tread left, but was ancient.
 
Take a car key and try to push it into a thick part of the tread, how big of an indent can you make, it's sort of a Brinell bush test for rubber,
they look hard as **** from here.
 
Those are hard tires, but given the 50KM traveled and the heat yesterday they should have been as grippy as they get. I've slid RP4s rounding right turns a couple of times on paint. You would need a lot of pebbly debris to cause slide on a city street.

Low slide is one or a combo of too much braking or too much speed, or slippery surface. If you are off the throttle in gear through a hard right, weight transfers forward and traction is reduced to the rear wheel. Engine braking and a small amount of slippery surface can cause the rear to slide out - a panic brake grab on the front exacerbates the problem

Something else that can happen on really hot days is tarmac bleed, this happens when the tar in the road gets really hot and expands and softens over the pebbles in asphalt -- it usually makes patches of the road look shiny. It can make the road sticky in a straight line, and slippery during turns.

I presume you lost the rear?
 
Slide it around just for fun once in a while ?
some tires inspire confidence when you do that, others feel like they are going to pitch you into the ditch at any moment.
The confidence inspiring tires have Radial written on the side, they are expensive, available in a very limited selection of sizes and wear out quickly.
 
I did mention I've ridden this bike for approximately 30,000km and have a few hundred km on this tire. So no, not original rubber.
Date code 2819
Measured psi at 30
Key pushed into the rubber leaves an indentation for a few seconds.
I must have been pushing the bike harder than I realized. I have broken traction when I had kenda tires on it, but no sudden loss of traction like today. It does feel like a bicycle compared to my bigger bike.

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Definitely wasn't on the brakes. Maybe on the throttle a little but as I said I didn't feel like I was pushing the bike

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Michael0124 said:
Glad to hear you weren't hurt.

You mentioned it was an old road surface, around a right turn in an intersection. I've sometimes found it to be almost polished (for lack of a better word) from all the stopping and turning across that section. My theory (no scientific thinking here, just a guess) is that over time the surface wears, smoothes out and loses some of its "grip". I've felt that slight sidestep from the rear tire a few times in similar situations. I'm wondering if that contributed to the slide.
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As far as I can tell, that was the biggest factor

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is that little rubber mould things still all over your tire surface? That thing isn't broken in yet, hit it with a belt sander :LOL:
 
Trials said:
is that little rubber mould things still all over your tire surface? That thing isn't broken in yet, hit it with a belt sander
Click to expand...
I've heard that before. Never done it. I might now. Most of the miles have been on kenda cruisers, but they were out of stock

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IIRC the entire sand your tires when new is a tip from a bygone era. Manufacturer's used to need to spray the injection machines with a release agent to get them to release from the molds, as result you'd end up with new tires with a slight oily coating on them. Modern manufacturing has solved this issue and breaking in a tire is more about getting used to the new compound/profile/etc. than exposing a fresh layer of rubber.

The only people who still sand their tires sit around at Leslie and Lakeshore comparing chicken strips.
 
I had a brand new set of Pirelli tires do that to me once, it felt like a slow motion crash, didn't slide far,
when I stopped I was still sitting on the bike :/ except very parallel to the road surface. FT500 so yes that was bygone era.
 
I like the ride harder idea, glad you suggested it and not me (y)
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