Wet cornering gear selection?

[puddy]

First gear in corners, wet or dry! Doesn't even matter if it's 25 kph or 95 kph.

[codgyoleracer]

Wet riding/racing & Gears,
You will go through some corners quicker by staying in a higher gear & saving yourself the hassle of changing down the extra gear & destabilsing the bike on a slipperish surface ( + of course the saved gear upchange coming out).
Matching revs & gear choice on the down change becomes more important also.
Other matters relating to gearing & the wet in racing conditions is choosing the right gear ratio's to run in the wet that relate to your reduced corner entry/exit speeds.

Obviously there is a bunch of other stuff outside of "gear choice" to consider for confident wet weather racing.
GlenW

[Toast]

Interesting that most of the votes have gone to high gear/ low revs, but the comments don't necessarily reflect that.

The reason I ask this question is because I had a small low-side caused by loss of rear wheel traction while going through turn 3 of a soaked Taupo track last week. I'd had a few spin ups through other corners of the track, usually when in a lower gear with the revs up, and rode those out just by keeping the gas constant. This particular corner I'd been using 3rd gear with moderate revs, about 9k rpm. When the wheel did start to slide I used the aformentioned technique which has saved me many times (never had a high side, nor any crash I can think of that was caused by loss of rear grip), but the wheel was seemingly spinning so fast, so quickly that it wasn't going to come back (maybe cutting the gas slightly would help but it's not a course of action I'm used to).

There were other factors involved, including using a stiffer rear shock spring than I'd ever had in the dry prior to that day, but given other losses of rear wheel traction on other corners that day, I believe that it could've been saved a lot easier by using the higher end of the revs as opposed to the miid range. Free traction control, like Sully says.

[jrandom]

Interesting that most of the votes have gone to high gear/ low revs, but the comments don't necessarily reflect that.

Could be a difference between road and track riding focuses. I'd say that a lower gear and higher revs might make a small slide slightly more likely, but more controllable, whereas a higher gear would give you a lower chance overall of breaking the rear loose, with a greater chance of landing on your arse once it did. Perhaps I'd go for the former for the track, and the latter for the road. I don't really know; haven't been on a track yet...

I guess it'd make a huge difference what sort of bike you were riding, too. I'm spoiling myself by riding a K2 thou at the moment. At 'moderate' road speeds, gear selection and engine revs don't really matter.

[kiwifruit]

Could be a difference between road and track riding focuses.

good call babe

[Toast]

Could be a difference between road and track riding focuses. I'd say that a lower gear and higher revs might make a small slide slightly more likely, but more controllable, whereas a higher gear would give you a lower chance overall of breaking the rear loose, with a greater chance of landing on your arse once it did. Perhaps I'd go for the former for the track, and the latter for the road. I don't really know; haven't been on a track yet...

I guess it'd make a huge difference what sort of bike you were riding, too. I'm spoiling myself by riding a K2 thou at the moment. At 'moderate' road speeds, gear selection and engine revs don't really matter.

I'd hoped that posting this in the racing forum would have kept the focus on track riding, but yeah, I had suspected what you mention.

I don't know why you'd want to have an uncontrollable slide on the ride over having one on the track though. I'd way rather bin it on the track.

[jrandom]

I don't know why you'd want to have an uncontrollable slide on the ride over having one on the track though. I'd way rather bin it on the track.

More like, I wouldn't want any sliding on the road, so I use much lower revs to make sure that it's not likely to happen. A small slide is fine on the track, but on the road there's too much going on, too much chance of unknown variables. So many corners with random crap on the surface, so many cars that cross the centerline. Better not to have to deal with the rear wheel doing anything other than tracking straight and solid, and your best chance of keeping it that way without any 'moments' is to keep the revs down.

[Toast]

More like, I wouldn't want any sliding on the road, so I use much lower revs to make sure that it's not likely to happen. A small slide is fine on the track, but on the road there's too much going on, too much chance of unknown variables. So many corners with random crap on the surface, so many cars that cross the centerline. Better not to have to deal with the rear wheel doing anything other than tracking straight and solid, and your best chance of keeping it that way without any 'moments' is to keep the revs down.

My problem with that is if you hit random crap such as a tar snake or some oil, you will be spinning up in any gear, at any revs if you are rolling the gas on. Since it's going to happen anyway, I'd rather have it be more controllable.

[jrandom]

if you hit random crap such as a tar snake or some oil, you will be spinning up in any gear...

Not necessarily.

The likelihood of the rear spinning up at a given speed on the road is proportional to the torque being exerted through the drivetrain. More twisting force applied to the wheel at the same speed of rotation makes it both less likely to stall, and more likely to lose traction.

Higher revs, geared down, means more twisting force at the axle for the same speed of rotation. 'Torque multiplication' is the applicable phrase, I think.

Therefore, all other things being equal, a loss of traction at a given speed on a given surface is more likely in a lower gear at higher revs.

The physics don't lie, and if you think about it, it matches the average rider's 'seat of the pants' experience, too.

[Toast]

I agree that a loss of traction is more likely in a lower gear, at higher revs, as I stated in the very first post.

My experience is that on a wet tar snake or some oil there is effectively, for a bike with more than 15 degrees lean on, zero traction to be had. So once on such a zero traction surface and with the throttle being rolled on, you're losing grip and the back wheel is accelerating however little 'twisting force' you've got going to the back wheel. And unless your throttle hand is perfectly matched to or below rear wheel speed, then the back wheel is going to go sideways quickly.

But road riding and hitting patches of shit in the wet was not the point of this thread.

[jrandom]

... road riding and hitting patches of shit in the wet was not the point of this thread.

Yes. I know. Sorry, I'll shut up now.

And agreed re. having SFA chance of maintaining traction at any sort of lean if the wheels hit road spooge.

[slowpoke]

I remember reading an article about the 500cc boys using the clutch to modulate wheelspin. Something about better dexterity with your hands, the clutch isn't as on/off etc.

[Sully60]

I remember reading an article about the 500cc boys using the clutch to modulate wheelspin. Something about better dexterity with your hands, the clutch isn't as on/off etc.

Yeah the clutch can be a really usefull way to limit torque and therefore control traction. I never used it on a 500 (cos talking about them is as close as I ever got) but I have used it in extremely slippery conditions on and off road. In quite a few situations off road the clutch lever is right in and I'm just bicycling through them, these are situations were you cannot use any torque being it under power or throttled off and using the back torque (from 4-stroke enduro and MX bike experiences) Though I did crash my YZ motarding on a wet kart track from not carrying throttle or freewheeling clutch in, got to the apex with a closed throttle and spun around like a top and ended up facing the way I came. Too much back torque, I might as well had jammed the back brake on mid corner from the way it "spun out".

As I said in my earlier diatribe this technique might not apply to all situations and it's probably not as necessary on the race track, but when the shit has totally hit the fan it's an easy way of keeping the bike a bit more balanced front to back so you can concetrate on keeping the thing going were you want it.

If you haven't already got one or have access to one get a dirt bike and go ride in the rain, you will fall off, lots but if you stick at it you gain skills that make riding on wet tarmac seem like a doddle. Practicing is the best way to improve but you don't want to trowel your road/race bike trying stuff like out, do it on the dirt at 1/4 the speed so stuff (like your legs and arms etc) doesn't break.

So as the experienced heads have said earlier in this thread its all about being smooth and applying the torque (forward or back torque) in a smooth and predictable manner.
Another two cents spent on this thread, well spent if you take away one thing that helps you out.

[James Deuce]

Jrandom has hit the nail on the head.

OAB posted a vid of him crashing his GSXR on track. In the dry, but bear with me. OAB was using surprisingly few revs to go very quickly. When the rear lost traction it spun up blindingly fast and as it went through the engine's peak torque output the bike spat him off.

Same thing happens in the wet. If you ride around in the broadest, flattest part of the torque curve it all feels a great deal less twitchy. It means using more revs than you'd think sensible though. Niall McKenzie spoke about the very same technique in a recent issue of TWO magazine, along with pointing out that you need to be reasonably committed in the wet to keep your tyres in contact with the road. You can also brake just as hard in the wet in regard to peak braking force, but you have to be gentle and build up to that peak a little slower than in the dry.