BMW R1200R R1150R/T F800 K1200R R1100R/T R1250R RnineT Message Board

I kind of gave myself an unintended shot of adrenaline Wednesday morning. It had rained the night before, but had stopped several hours before I rode, around 9:00 AM. The temperature was probably in the high 40's/low 50's. The roads were still wet but it wasn't raining - I've ridden on these roads when it is raining, so no big deal. I rode about a half mile - I full stopped at the stop sign and then turned left. These are streets obviously very close to my house, so I've done this many times. I'm leaned into the left turn and moved it up into second. I let out the clutch and my rear tire lost traction, slid out what felt like a fair amount to the right, then regained traction, almost violently. The rest of my ride (to work) was very slow.

My tires aren't worn - fairly new Avon Azaros with about 2,000 miles on them. Ironically I chose them because they're Brit and I figured they must be good on wet pavement. I didn't see anything obvious on the road - I actually went back to take a look. No oil slick, no wet leaves (I live in Massachusetts), etc. I don't think I let the clutch out too quickly or over-revved the throttle. Could it be that my tires were somehow cold and not yet grippy? I ride a '99 R1100R (with ABS although the brakes were not a factor in this). It was modified by the previous owner with a performance chip and exhaust system (no cat) - don't know if this makes the bike more torquey and this was at least part of the deal?

It was you....and also wet roads often hide little surprises in them...

DJ

What do you think I did wrong? I've taken that left turn hundreds of times including when the road's been wet.

From what you wrote, I take it you shifted into second gear while in a turn? IF so, thats a bad idea in dry weather and rain all the more. Textbook says rollon throttle thru turn. Shifting during a turn in rain is asking for trouble.
Glad you were able to ride thru it tho!

Just timing...It's never a good idea to upshift or downshift when leaned even a little into a curve on wet surfaces. Even a slight change of torque in rear wheel can reduce the already low friction to nothing and make the rear wheel slide out. At least have fully engaged the new gear before you're leaned even a little.

Silverr wrote:From what you wrote, I take it you shifted into second gear while in a turn? IF so, thats a bad idea in dry weather and rain all the more. Textbook says rollon throttle thru turn. Shifting during a turn in rain is asking for trouble.
Glad you were able to ride thru it tho!

So, keep it in first, even though it's for a longer time than I normally would? There were cars coming and I wanted to get up to traveling speed.

Yeah, i would keep it in first and get thru the turn and headed straight, then get up to speed. Even better, give yourself more of a gap to be safe. Either way, its good to have steady throttle with slight acceleration rolling out of the turn, improves rear wheel traction. Coasting out of a turn or shifting hinders rear wheel traction.

When it hooked back up, did it almost high side you? Cheap thrill i bet

Yes, keep steady or slightly increasing power through the turn. As soon as you pull the clutch in you'll lose traction if you're leaned over in a turn. What rpm are you shifting from 1st to 2nd? The Roadster has a pretty tall first gear. You should be able to get going pretty good in 1st.

Any gear throttle munipulations will be exaggerated in the wet. I nearly lost a company car on a ramp I do all the time last week on a diesel spill.

Once I turned right after a rain at a turn I do all the time and felt the rear wheel slip once, twice. Looking back, I realized I had been leaned over going over the painted cross-walk lines, which are slick when wet!

Yep, I've done the painted line "dance" already. Definately woke me up! After a quick stop in the nearest bathroom , I was ready to go again!

GJBushman wrote: What rpm are you shifting from 1st to 2nd? The Roadster has a pretty tall first gear. You should be able to get going pretty good in 1st.

I'm shifting around 4000 - 4500 RPM. Should I shift at higher or lower RPM in the wet?

Jimfromdover......

I see two possible scenarios, which compound each other.....the shifting that has already been talked about and maybe the presence of a little oil and water on the road surface.

Those two will make things happen very quckly.....so if your street or the streets you travel have a lo of traffic, specially trucks, be in the lookout for the above......

I'm shifting around 4000 - 4500 RPM. Should I shift at higher or lower RPM in the wet?

That sounds about right although I find myself shifting at lower revs when it's wet.

It's more about how you shift and where...ie..not while leaning..not while crossing painted white lines or tram tracks..and not while doing a tight turn or anything off camber.

Also you need to be very smooth with the clutch..almost feathering it..expecally when changing down...I once got a tip about running with the fast idle on in the wet and I sometimes did that and it seems to work also.

I'm no expert..it's just my personal thoughts..take it easy..ride safe..nothing beats experience.

DJ

I get out of 1st gear as soon as I can. Sometimes I shift 2 gears at once to keep in the torque range. Maybe the 4-4,500rpm is too high. I dont usually get anywhere near those rpm, I just use the torque, 2,500rpm-4,000rpm, even on the open road.
Experience will tell you how to ride to suit you.

This may have nothing to do with your slip, but here in Florida the slickest road conditions are caused by very light rains that float the accumulated grease and oil from the pores in the pavement and emulsify them without washing them away. The road surface, especially at intersections where oil drips from cars waiting at lights and stop signs (and especially at toll booths), can be as slick as Virgina black ice and will put you down in a heartbeat. As David Hough mentioned in his excellent riding manuals, "Proficient Motorcycling" and "More Proficient Motorcycling", you've only got a finite amount of traction available at any the time, and in corners much of it is used to keep the bike turning, so other traction-using actions, like braking, accelerating and shifting (which upsets the balance of the bike on the front and rear wheels) should be avoided if possible.

These bikes are so torquey that sometimes the throttle needs a very light touch!

DJ's trick to use the high idle to keep from decelerating too hard might work well down here...I'll keep it in the memory bank for future use. Thanks Mate!

I use the high idle trick every time it rains, for me it works.

Silverr wrote:When it hooked back up, did it almost high side you? Cheap thrill i bet

It did feel like a high-side kind of motion, but I don't think the rear tire was out of line far enough (or maybe I was going too slow) to really high side. But it did get my attention, for sure.

[quote="DJ Downunder
Also you need to be very smooth with the clutch..almost feathering it..expecally when changing down...I once got a tip about running with the fast idle on in the wet and I sometimes did that and it seems to work also.
[/quote]

DJ

I like your tip about running fast idle. The thought has crossed my mind in other situations, like trying to make a tight U-turn - the 'torqueyness' (I think I jsut invented a word) of my bike makes smooth tight turns difficult.

So, in my loss of rear wheel traction, my RPMs were too low?

you might think of traction as money. the amount of traction you have available is the sum of the grippiness of the tire plus the grippiness of the road surface. riding on wet roads costs you some (this is probably the biggest factor). turning costs you some, more at higher speeds. accelerating or braking (even engine brake) costs some. This is especially true in the lower gears because torque amplification at the wheel is greater.

you surpassed your available traction limit, with the combination of all three.

it sounds like as you let out the clutch you applied just enough engine brake to put you over your available traction limit. you just slightly, briefly exceeded your traction limit. just enough to let that wheel slide for an instant. it took a second for the tire speed and the engine speed to match up, at which point you regained traction. when the tires regained traction they were out of alignment. they abruptly aligned themselves and gave you the quick "high side" jolt.

the best advice was probably to get yourself in a staight line before the shift. slightly higher engine rpms(as second gear is engaged)and delicate clutch finesse may also have kept your traction account in the black.

My system is to shift early,,,in another words make all the shifting tall. In the rain you dont want that wonderfull R torque to bring you down. Also it sounds like where shifting in the middle of a turn..mmmmmm a no no for sure! Hey you now what you learn and it made you a better rider right!