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Old 06-05-2014, 09:01 AM   #1
phreon OP
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My 1st Motorcycle Exit. Help me figure out what the hell happened?!?!

My vitals: I've been riding about a year, took the MSF course last summer. My 1st bike was/is a Vulcan 500. I love that thing, I ride to work when I can, have taken extended weekend road trips on it, have fun on twisty roads, etc. I'm just comfortable with it. I got an old, beater Nighthawk 750 a couple months ago that I've been fixing up. Aside from feeling kind of top heavy at first, It feels very smooth, comfortable, well planted and much easier to handle at slower speeds, if not kind of "pig heavy" when transitioning side to side at higher speeds. I've been careful to be mindful of the additional power and lackluster front brake, but it seems very manageable.

This morning I was on my way to work, just leaving my neighborhood and heading down a hill that takes me to a main road that then leads to the highway. Morning weather in the high 60s at most. Maybe 3 minutes of riding tops. There's a little connector road with a semi-tight left-right I've negotiated countless times on my Vulcan and maybe a dozen on the '750, I leaned in to make a left and the rear tire just gave up. I couldn't have been going more than 10-12 MPH. Maybe it's lying to me, but my memory tells me I was down in first gear, had completed my braking before turning in and didn't do anything stupid like nail a brake, pop the clutch or goose/snap the throttle. Pavement was bone dry and I saw no evidence of oil, gravel, etc. I'm ok with nothing more than minor rashes and a purple, swollen pinky finger. My gear did the job and I didn't even burn through my jeans. The mirror & turn signal are smashed, the handlebar is tweaked and and muffler is scuffed up, but after clearing the flooded engine, she fired right back up and I rode it back home.

I'm trying to figure out what the h3ll happed? I have noted the Nighthawk's rear feels *much* more sketchy on the occasional gravel or sand than the Vulcan 500, but that's about it. Also, the '750 is wearing Metzler 880s, which do seem much easier to lock up with the rear drum brake when cold than my Vulcan, but I could swear I never touched the rear. Do the ME880s suck until warmed up? Any other ideas? I'm an engineer and can't stand not understanding what happened.

Thanks!
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Old 06-05-2014, 09:11 AM   #2
pilot
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Had you lubed the chain before the ride? It is easy to get some over spray on the tire causing the low side. An experienced rider would never do something like that, though.
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Old 06-05-2014, 09:45 AM   #3
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You may not ever know exactly what happened. I can draw from your story a few possibilities, but I wouldn't say any of them are "it" or such, just some possible variables.

Morning dew. It stays longer than many realize, especially in shaded areas. Just a wisp of it makes pavement surprisingly slick.

Road dust. All but undetectable, but it tends to be there, especially at intersections. From tire wear to pulverized sand, leaf detritus, etc.

Pushing. With comfort comes speed. That line between having traction and not can be easily pushed through, especially with a new bike, and especially a newish rider on a new bike.

More lean. A little different than the pushing mentioned above. This is where you lean a tire, especially an older tire, further than it's been leaned in some time. Where older harder surfaced rubber that hasn't touched asphalt in months now touches down. And, goes sliding along.

1st gear. That's a violent gear. Well known for exceeding traction limits. Be it a rolled on throttle in a turn (doesn't take much), or a clutch engagement where engine braking adds just enough force to push the tire outside the traction circle. That wheel hops when going straight, and tends to slide when in a turn.

Hard rubber. Old tires especially. They work fine in straight lines, but are much less forgiving in a turn. Especially if you lean further and are now on rubber that hasn't scrubbed asphalt in quite a while.

Washing and cleaning. Similar to the previously mentioned chain lube. This time with detergents and waxes and rubber dressings. Over spray happens, and it can be darn slick. Doesn't wear off the edge of a tire until you lean it over in a turn.

Just a few thoughts.
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Old 06-05-2014, 10:22 AM   #4
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All the above are good things to think about, and some slippery stuff like coolant does not show up on the road.
Some tires are hard and slippery also, and some bikes are a handfull at low speeds.
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Old 06-05-2014, 10:28 AM   #5
Merlin III
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Other than there being something slippery on the road, I don't see how this could have happened at a speed of only 10-12 MPH. One thing that caught my attention though was that you "leaned into" the curve? I'll have to go for a ride and observe what I do in that scenario, but I would never imagine my "leaning into a curve" at 10-12 MPH? Maybe it was the "Cocktail Affect" which is a little bit of many variables?
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Old 06-05-2014, 10:45 AM   #6
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A month ago I was on group ride down in Virginia.

On some very twisty 2nd gear turn roads. Day went well, fast riders.

We went over the top of a hill/mountain and started down the other side. Halfway to the bottom the lead rider suddenly slowed- just about when I felt like I had a rear flat tire.

Dry road surface, no dirt. But very slippery.

Perhaps pollen- it had been a very late winter and a short spring there.

Never found out.
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Old 06-05-2014, 10:55 AM   #7
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You were probably going comfortably faster than 10mph. On the road, I never go back to first, unless I'm at a full stop.
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Old 06-05-2014, 11:52 AM   #8
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My vote is for old tire with hard rubber.
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Old 06-05-2014, 12:02 PM   #9
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I'll say I *think* I was in first. As a matter of course, I downshift to to match speed. Compared to my 6 speed Vulcan, 1st on the 'hawk is very tall. Where the Vulcan 500 has *strong* engine compression and 1st gear that I never downshift into until I'm going a few MPH (get a KLUNK if I do it too early), 1st on the 5 speed Nighthawk is useful for things like neighborhood corners.

And admittedly, I do lean the 'hawk deeper than my Vulcan on occasion. The Vulcan's pegs are a limiting factor and the 'hawk seems so much more planted as well as more stable/predictable at lower speeds. When I say "leaned in", I'm guessing 15-20 degrees at most. When the rear let go, it was utter shock. A quick flash of, "How is this possible?!?". I was going slow enough that the spill only caused a scuff on my jeans, it didn't burn through. In my life, I've received MUCH worse rash from being stupid on a bicycle or skateboard. Beyond the expected tweaked handlebar and destroyed lights/mirror, the only other significant damage is a rashed engine/crank cover. Quite irritating since I have engine guards in the garage I haven't installed yet.

We did have *heavy* rain yesterday, but the intersection looked perfectly dry and scum free.

There should be a date code on the tire somewhere, right? Has plenty of tread and no signs of crazing.

I'm not discounting that it was likely my fault and / or a new rider error. Given how smooth the bike feels, maybe I was more aggressive than I thought. I do know however I've pushed the Vulcan significantly harder with no problem whatsoever -or at least it feels that way. Regardless, I want to learn from this to make sure it never happens again.
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Old 06-05-2014, 12:13 PM   #10
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Throttle?

What was happening with your throttle through the curve? could be a little too much gas could spin it and create slide especially if the tires are old...did you put the Metzs on or were they inherited?
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Old 06-05-2014, 01:00 PM   #11
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The previous owners claimed they put the 880s on about a year ago. Given the tread, I have no reason to doubt them. Who knows if they sat in a warehouse though. I have heard these are comparatively hard tires.

Everything I've mentioned is from memory. It happened so fast, what I've recounted could be wrong. I don't believe I goosed the gas, nor am I in the habit of doing that in turns - this exact scenario is why. Also, the 750 really doesn't lay down power until it's above 3000 RPM or so. Comparatively, my little 500 is noticably torquier at similar speeds (lower rpm).

I will say that I've skipped my jacket a few times on really hot days. NEVER AGAIN.
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Old 06-05-2014, 02:22 PM   #12
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http://goo.gl/maps/JVYVe

The above should load a Google map street level view. Needless to say, the construction equipment and junk in the road in the picture isn't there.I was on the right side of the double yellow line and made a left. My bike came to a rest against the outside curb "behind" where the flagpole is in that view. My rear tire came loose *exactly* where the double yellow line resumes through the intersection.

Come to think of it, that's a huge coincidence, isn't it? Or maybe I was in the "scum line".


Thanks

phreon screwed with this post 06-05-2014 at 02:34 PM
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Old 06-05-2014, 02:42 PM   #13
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It can take a pebble to put a tire past it's traction limit and initiate a slide when least expected. The tough part is when you look for a cause that pebble got rolled to the curb. That's my "guess" and I am sticking with it!
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Old 06-05-2014, 07:29 PM   #14
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I had a similar off when I was a young lad on a borrowed Suzuki GN400. Very slow corner which I had done a hundred times before. I hit a small depression just at the apex of the turn while well leaned over. It was enough to compress the suspension a little and touch the pipe down. Instant lowside at about 15mph. The pavement went through both coats I was wearing and JUST touched my right elbow. I stopped with my left foot still on the peg, the clutch pulled in and the bike still running. I stood it up and continued on my way. Other than the well scuffed pipe there was no damage to the bike. I was a lot more careful on low clearance street bikes after that!
Regards....justjeff
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Old 06-05-2014, 08:32 PM   #15
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Quote:
Originally Posted by phreon View Post
http://goo.gl/maps/JVYVe

The above should load a Google map street level view. Needless to say, the construction equipment and junk in the road in the picture isn't there.I was on the right side of the double yellow line and made a left. My bike came to a rest against the outside curb "behind" where the flagpole is in that view. My rear tire came loose *exactly* where the double yellow line resumes through the intersection.

Come to think of it, that's a huge coincidence, isn't it? Or maybe I was in the "scum line".


Thanks
Painted lines can be really slick, especially with water, dew, oil, coolant, etc. Did you loose traction on the double yellow? Was that center section of the pavement darker like it is in the picture? That means 'don't lean it over here'.
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