Rear wheel slip, was this "shaft effect"

[Rory]

how cold was it out there? Snow in the mountains? I would be careful about lean angle + power when it's cold. The tires will not warm up if the pavement is cold.

 

[wabill]

Well I think I'm safe to assume from the responses that the slippage issue will be corrected at the next tire change.

My other bike which does the same roads wearing Dunlop RoadSmarts with confidence, is a Trimph Speed Triple which at only 470 lbs, perhaps 110hp at the rear wheel and a very "quick throttle" demands a sensitive right hand.

I really appreciate the discussion as this is my first machine with shaft drive. My thoughts on the shaft jack issue were that if the effect is to lift the frame of the bike up, then the tires should be pressed harder downward. But as Fred W pointed out, that when leaned over, downward is outward.

I think that the FJR is a tremondously fun and very capable bike. Last month while in NMex I had no trouble keeping pace with these two riders on their Daytona 955s and never a slip. Temps there were not hot but were a whole lot warmer than 36-47 deg. going over N. Cascade Hwy. Perhaps the lesson to be learned is not to play hard on these tires when the weather turns cold.

Thanks to all for your input.

 

[Bounce]

Sounds like grip between the tire and the road to me...not a question of how the power was delivered to the rear wheel...

+1 sounds like he applied more tq to the wheel than there was grip at the tread.

the FJR also has a lot more tq than the speed 3 so imprudent tromping on the throttle, mid-corner, has a different affect.

 

[ahchiu]

You most likely hit some gravel, I have riden that road and it is hard to see small patches of gravel, it happened to me on the same streach. The next time I rode this I was behind someone and saw gravel comming off his back tires.

 

[wabill]

You most likley hit some gravel, I have riden that road and it is hard to see small patches of gravel, it happened to me on the same streach. The next time I rode this I was behind someone and saw gravel comming off his back tires.

For those that know the road, it was at the bottom of the downhill coming from the Diablo Overlook and the corner was the bottom curve onto the bridge at Colonial Camp. No traffic and had an excellant line and the paving looked good so gave it mild thottle in the apex. No idea of what speed was being carried but don't believe it was too hot for conditions.

It doesn't sound like it had anything to do with shaft jacking, which was the question of the thread, and more like cold road and tires.

 

[Bungie]

For those that know the road, it was at the bottom of the downhill coming from the Diablo Overlook and the corner was the bottom curve onto the bridge at Colonial Camp.

You mean here?

Some more pics from Diablo Lake:

I actually have a pic of my bike on that EXACT corner, but its not on my photobucket! I bet your bike skipped out just as you enter the bridge. You can even see a dip in my pic.

What the hell were you doing hauling *** on that road! LOOK at the scenery.. JUST LOOK AT IT!

 

[Big Sky]

The discussion on shaft jacking (I wouldn't touch that one) is interesting, and reminds me of the first bike I ever purchased brand new ... when I was young and stupid: a 1980 Yamaha Maxim 650 w/shaft drive. Of course, I was into burnouts then... You could rev the Maxim up, drop the clutch, and it would lay rubber for three or four feet before the back end came up so hard and far the tire came off the pavement - no rubber, then another streak as the tire returned to earth. Funny I didn't destroy that bike; the friend I sold it to did, though.

 

[wabill]

For those that know the road, it was at the bottom of the downhill coming from the Diablo Overlook and the corner was the bottom curve onto the bridge at Colonial Camp.

You mean here?

I actually have a pic of my bike on that EXACT corner, but its not on my photobucket! I bet your bike skipped out just as you enter the bridge. You can even see a dip in my pic.

What the hell were you doing hauling *** on that road! LOOK at the scenery.. JUST LOOK AT IT!

Nice pics! Yep, that's the spot.

That 'dip' could well be the answer. Shoot,if the dip did it, confession, it could be the 'soft settings' on my suspension that I never tightened up after the last months road trip. As to stopping for pics, I really don't do enough of that as my pics are usually a disappointment to what was seen.

 

[wheatonFJR]

wow...what a beautiful area...tire slip or not.

 

[Fred W]

The discussion on shaft jacking (I wouldn't touch that one) is interesting, and reminds me of the first bike I ever purchased brand new ... when I was young and stupid: a 1980 Yamaha Maxim 650 w/shaft drive. Of course, I was into burnouts then... You could rev the Maxim up, drop the clutch, and it would lay rubber for three or four feet before the back end came up so hard and far the tire came off the pavement - no rubber, then another streak as the tire returned to earth. Funny I didn't destroy that bike; the friend I sold it to did, though.

That's actually a slightly different fun phenomenon of shaft driven vehicles known as "Wheel Hop". It is caused more by the wind-up of torsion in a sloppy drive train and suspension than the shaft jacking effect at work.

It is however a really quick way to destroy a drive train and was always lots of fun with the crappy **** box cars of my youth.

PS - Props to Bungie for introducing some beautiful pics of the crime scene into this bench racing.

 

[Bungie]

wow...what a beautiful area...tire slip or not.

No ****! I said in my original post in this thread that its my new all time favourite scenic ride. Now you see why. I don't remember who suggested it to me, but the next morning leaving Winthrop it was all I could do to turn left out of the hotel rather than right and run that road again.

Take a look at my photobucket slideshow of the trip, theirs at least 30 or 40 pics of Hwy 20 in there. All are breathtaking. Caution, may cause acute depression with winters onset.

The Gap, The Skyway, The Cabin, etc. from this past weekend.

'No permissions to view'.

 

[wabill]

I do take some pics while on the road. Here's Rainy Pass on May 1, 2008 opening day.

My ride at the time gives the shot some perspective.

 

[ahchiu]

For those that know the road, it was at the bottom of the downhill coming from the Diablo Overlook and the corner was the bottom curve onto the bridge at Colonial Camp.

You mean here?

I actually have a pic of my bike on that EXACT corner, but its not on my photobucket! I bet your bike skipped out just as you enter the bridge. You can even see a dip in my pic.

What the hell were you doing hauling *** on that road! LOOK at the scenery.. JUST LOOK AT IT!

Nice pics! Yep, that's the spot.

That 'dip' could well be the answer. Shoot,if the dip did it, confession, it could be the 'soft settings' on my suspension that I never tightened up after the last months road trip. As to stopping for pics, I really don't do enough of that as my pics are usually a disappointment to what was seen.

The picture in your first post is a further down from the road from where you said you had the slip, same road different location so the dip could very well be what you felt.

 

[RossKean]

I was there this year too! Beautiful ride on the 20. Very cold for the first week of July.

 

[maddad]

Picture shows it all. Snow in the mountains means colder air, colder road, colder rubber, harder rubber.

I've broken free my rear wheel twice, both times in the fall when it's cold.

 

[Bounce]

Let's try this again

PS - Props to Bungie for introducing some beautiful pics

2 can play that game.

The Gap, The Skyway, The Cabin, etc. from this past weekend.

 

[wabill]

Bounce, The 20 really doesn't rank well on a scale of Twisty Roads like the one you've mapped. The weekends,with tourist and camper traffic can make it a piss poor ride in fact. I guess when that happens you're supposed to enjoy the sights and stop for pictures.

Achiu, Sorry if it caused confusion. The pic in the first post does say that the a pic taken this past summer and wasn't meant to indicate where the event happened. Just showing some nice scenery with the bike in view.

 

[bikerkash]

I assume they were Metzeler's Z6's. I have went thought many sets of Z6 tires and have always found them to have excellent traction. The PSI you have set the tires to may be effecting this also. At 7500 miles the tires have worn to the point where this factor will effect the feel of cornering traction. I usually only get 6500 to 7500 miles when the steel belt in the center starts to show. I only ride one up and I set the cold tire pressure to 36F 38R. The air temperature also has an effect on tire grip. MC tires are made to operate in a certain heat range. If they are under that range they will tend to not grip as well and if they are over they will start to get slippery. A new set of tires always make the bike feel like a new one.

 

[CaptainK]

This is a pic taken on the road this past summer.

Looks like "Liberty Bell" curve to me(SR20). That eastbound curve starts out down hill and off-camber. But it ain't no swept race track.