"It Never Rains in California...", NOT! (tire traction...)

[CHPBike]

Okay, so it's a tire related thread. I rode on Saturday for 150 miles and part of that was over a 5,000 foot peak near Palm Springs. On that peak I hit tons of twisties, hard rain, fog, and blistering winds. I have a new set of Metzler Z6s on both the front and rear and the RT didn't falter. I hadn't had a chance to try them out on wet pavement before since I only had about 300 miles on them. As I was riding I was wondering just how much traction is lost on a very wet surface as compared to totally dry? Would one loose 10%? 30%? I haven't a clue and wished I'd known the answer as I was slicing through those tough conditions.

Anyone? :help

See you in Lima!

Scott

Dana Point, Southern California, USA, Planet Earth...

[Mike1]

I have Metzler Z6s on both the front and rear of my '02 1150 RT. I think a standard factory tire will have about 80% traction in the rain, and Metzlers much better than that. Metzlers are made for the Autobahn in Germany. My experience is the roads there are often wet. Although I do remember fishtailing through a stream over a mountain road one time, but managed to keep the bike upright. I think we all have a tendency to slow down some in the rain, but not as much with my Metzlers. :brow Lima, yes.

[BobFV1]

I have Z-6's on my 04 RT. Last Tuesday I was riding from Phoenix to LA and got caught in the big SOCAL rain storm - started raining in Yucaipa and finally had to stop in Pasadena because of lack of visibility - but my tire grip was fine. I have never lost enough grip on the Z-6's in the rain that I had a significant loss of traction. I think they say sticky enough in al conditions to match and in most cases exceed my riding skills. Great tires!

[knary]

There isn't a pat answer. A wet road, as you know, is often not just wet but has debris or other substances mixed in with the water. So how much traction do you have? dunno. less. :D

A better question: if you only have, for example, 80% as much traction, what does this translate to in real riding terms? Can anyone answer this? I'd bet that even Rossi doesn't know - he just rides the bike a little differently.

[DarrylRi]

Knary has it exactly right. I lived in Seattle and rode all the time in the rain. I never let it bother me much, and while I didn't get down to the valve covers in the turns, I didn't tip toe through them, either.

But late one afternoon, I was cruising home along WA-9. I didn't see anything in the road, but it was a dark and rainy day and the road was reflecting what little light there was. Suddenly, as I was setting up for a turn, I had no traction. The front tire locked up (R90S, no ABS -- if you've ridden a /6 you know that those first disc brakes aren't real strong). I got off the brakes and managed to save it, but now the turn was coming up and I needed to lean over. But it felt like I was on marbles. (I still didn't see anything in the road!) I braked, more gently, and then leaned, but I ended up on the valve cover anyway. It turned out that there was a fine spray of asphalt gravel distributed through the turn, the water was deeper than the gravel, so it didn't poke through the surface, and the reflected light hid it completely.

Up until that point, and after it, I had fine traction on the old tube-type Metzlers (ME-33 / ME-88) on that bike. I wouldn't worry about normal traction in the rain. I would worry about stuff in the road, or fuel or oil on the road.

[Mr. Frank]

I've seen that 80% figure a number of places. It's important to note that that assumes a clean surface (no mud, oil, sand, etc.) and no standing water. That would most likely be the case with a wet road after a hard rain has ended. Whenever it is raining hard, there is going to be some standing water.

[billyfields]

I have been driving beemers since 75. Even did a trip to Panama from Montreal in 1980 - so I have a lot of road experience. Over the years I have on several occasions experienced hydro plane-ing - always at highway speeds in fairly heavy rain when suddenly coming upon surface water. Scary but at least I can understand it.

Well last fall I had an experience that has me questioning everything I thought I knew about driving on wet roads. I drove to Niagara Falls for a Sunday morning ride. Over breakfast (Falls Manor, Lundy's Lane - recommend it highly!) it started to rain. I though that I would wait it out so I languished over coffee. Well finally I'd had enough coffee and even though it was a blooming deluge, I set out for the 100km drive back to Hamilton. It was raining VERY hard and I was nervous about the traffic so I got off the (secondary) highway and started to take concession roads home - these are the grid roads that pass through the farm country - straight, paved and usually quiet.

The rain had eased somewhat and I was on a well crowned two laner. The asphault was the "grainy" type (slightly bumpy from the gravel mix) and apparently new from the lack of cracks and patching. I have always come to associate this type of surface with better traction because the sight roughness should give tires more to bite into. I was watching the surface carefully, it was wet but clear of water accumulation. At a very modest 60 km/hr (less than 40 mph) the motorcycle (R1100RT) started to do something I have never before experienced on a bike - it began to oscillate very slowly from side to side, literally pointing its nose from one ditch to the other even as it continued straight ahead. At the extreme pitch of this oscillation, I was literally sitting straight upright on the bike while sliding sideways down the center of the road and staring at the ditch in front of me. I was actually afraid that at any moment the tires would recover their grip and send the RT and me into a side over side roll. What was happening made no sense. Anyway, my instinct (or was it terror?) was not to flinch - not try to steer or brake - all I did do was ease off on the throttle e-v-e-r so slowly. I went through 2 or 3 full cycles of this. 10 or 20 seconds.Then the oscillation just damped out and I was pointing ahead.

Here is where I am still a little ticked with what I did next. I just kept driving - I think I was in shock. What I should have done was gone back to the site and examined the road. I still have no idea what caused this to happen so I am no wiser. I am left with a theory - the surface was greased. Oil, manure, clay - what ever it was I could not see it.

BTW, the tires were nearly new Metzler M6's.

Anyway, live and learn - or perhaps its the other way round?

[Mr. Frank]

Wow! I'm guessing you destroyed a good pair of pants. As slow as you were going with good tires, it probably wasn't hydroplaning. Your hunch about some kind of surface contamination is probably what happened.

[BiffsR]

I seem to have always get stuck with a rainy day when I am on a trip, and the first 20-30 minutes in the rain are the slickest. All of the oil, grime, etc is being washed off of the street in that time frame. After that the wet road is not much of a problem.

BTW, I had a Z6 rear tire on my old 1150R with a Z4 front. I thought the Z4 was a little better in the rain, but the Z6 was still superior to the Mich Macadams. FWIW, I had the mixed pair because the Z$ rear got a big nail when it had about 1500 mi on it.

It seemed like the metzlers would get a little squared off after a long trip on the slab, but a day in the twisties would round them out again.
:thumb