Weight transfer?

**dpex** · 28th October 2008, 17:20

I had a couple of 'interesting' experiences today. Came around a sweeping RHer and cut in. Grandpa's head ws over the centre-line and a cage was coming through the same corner, albeit from the other direction. Oops!

Now I'm in the shit. Halfway through the corner (badly set up) and now needing to keep my head on my shoulders. Panicked, just a bit, and went stiff armed, which just set up a left/right oscillation (speed wobble). Ooops! Ooops!

Anyway. I survived the event but pulled over to have a wonder at what happened. Never done cornering speed wobbles before.

Turned around, went back past the corner and came at it again; albeit sitting quite upright and going a bit slower, just to see if I could notice what might have gone wrong.

Two things came out of this 'test'. 1) I noticed my arms were rigid (elbow locked) and realised that cvost me some control. 2) This was the biggie (I think). I noticed I laid the bike down to the right but moved my weight to the left.

So I stopped to consider these issues and consider a possible solution. Stiff arms and weight-shifting the wrong way.

"Maybe I need to get down on the tank?" Don't know enough about bike dynamics to reason it through, but somehow the idea seemed to have merit.

So back up the road I went and came back at the corner with arms very bent and weight hard down on the tank. At first if felt very uncomfortable till I realised two things (albeit in the parts of a second one gets to notice 'stuff' in a corner. 1) Bent arms meant I couldn't force the counter-steer, it just seemed to happen. 2) Being down on the tank my body was locked with the bike's angle.

So I went back and did it again. This time with a bit less worry on account of the first time actually felt both good but unnatrual...if you see what I mean.

Second shot, much better. So I did it again. This time with a lot more speed..and in a lower gear (3rd at entry speed of 100Kph..and a small bit more). Same result. Comfortable, in control. But still felt a bit unnatural. I think the unnatural bit was that my weight/position had to go with the bike.

Thought about that for a while, then went back and did it again. Felt really good. I realised I'd got into this stiff armed, opposite weight-shifting habit without realising.

Every serious corner from there to the rest of the ride it was chest on the tank, soft elbows, and to my great pleasure a sense that I had much greater control.

Your comments on the whys and hows of this would be welcomed.

**dpex** · 28th October 2008, 17:32

As I nearly always do having been confronted with an issue I don't understand, I went off to sundry to ask their expert opinion.

One thing which came from this was learning about 'trail-breaking'. Gavin, from Henderson Yamaha, a dedicated racer, mentioned this.

He asserts that "an" amount of rear brake pressure causes the arse-end to hunker down a bit and thus provide greater traction. I kind've understood the dynamics...kind've.

Notwithstanding, I have also learned, much to my heart's terror, that hard rear breaking in a corner is a recipe for bad shit happening.

But then later I asked Jason Godsmark (another dedicated racer) about it. He asserted the concept was good but hard to get right.

Anyone got any opinions on this issue?

**Hitcher** · 28th October 2008, 17:36

Sigh. I feel another "countersteering" thread coming on...

**Mom** · 28th October 2008, 17:36

Originally Posted by dpex

This time with a lot more speed..and in a lower gear (3rd at entry speed of 100Kph..and a small bit more). Same result. Comfortable, in control. But still felt a bit unnatural. I think the unnatural bit was that my weight/position had to go with the bike.

Here is my favourite thing about cornering, chose the right gear to go in makes life a whole heap easier. My advice is to actually slow down and think about what gear you need to be able to enter the corner safely and exit on power without hanging your head over the line. Your line into the apex of the corner is vital to where you head ends up. So, slow down, select a line, select a gear, and take that corner.

**FJRider** · 28th October 2008, 17:46

On both issues, life is a learning curve, if it works for you... who are we to say differently.
an "amount" of acceleration in a corner, also adds traction...

"Concepts" in motorcycling are not uncommon...(hence the RE5...) you choose what is good for you.

**MSTRS:Me** · 28th October 2008, 17:46

There is no need to 'hunker down' on the tank.
For road riding, leave your bum where it is on the seat, maybe shift your shoulders a little to the inside of the corner, Do your slowing as you approach that corner and change down a gear or two (that should provide enough engine braking without touching the brakes), move to the outside of the approaching arc, countersteer or lean to tip in, you will 'feel' the apex, now throttle on a bit, exit corner. Rinse and repeat.
It can help to tense your leg and push down on the outside peg too.

**dpex** · 28th October 2008, 17:48

Originally Posted by Hitcher

Sigh. I feel another "countersteering" thread coming on...

Aw, come on Hitcher, this isn't just about counter-steering. It's a whole dynamic I don't yet understand. I will, after I have questioned a whole lot more folk. But it would be good to get some opinions here.

**slofox** · 28th October 2008, 17:52

If you use rear brake in a corner, it is important to keep the throttle on as well. This stops loss of traction but allows some speed to be bled off safely. Better not to overcook your entry into the corner in the first place of course.....but if you are confronted with the unexpected, you can indeed use the rear brake - just DON'T throttle off....a delicate touch is good....

I always hunker down on the tank if I am out highway riding, especially on the sweepers or twisties. My weight is lower so COG is as well = better cornering. Besides which, it just feels right to me. I try to be part of the machine - let it do the work - all I do is direct it and that is mostly with body weight. I don't climb all over the bike either - I stay tight to the tank with knees and elbows in and just go with it...That way, I can relax .....one of the things I really like about riding a bike....it's like flying two feet above the ground.

**MSTRS:Me** · 28th October 2008, 18:20

Originally Posted by slofox

If you use rear brake in a corner, it is important to keep the throttle on as well. This stops loss of traction but allows some speed to be bled off safely. Better not to overcook your entry into the corner in the first place of course.....but if you are confronted with the unexpected, you can indeed use the rear brake - just DON'T throttle off....a delicate touch is good....

Good stuff

Originally Posted by slofox

I always hunker down on the tank if I am out highway riding, especially on the sweepers or twisties. My weight is lower so COG is as well = better cornering. Besides which, it just feels right to me.

Can't see the COG thing being lower by 'hunkering down'. Your weight is carried by the bike and is concentrated on the contact points...pegs and seat, and too a lesser degree the bars. By moving the bod about you are redistributing weight, certainly, but you are not lowering it.

**jrandom** · 28th October 2008, 19:14

Yo dpex, do the trackday on Friday, then read A Twist of the Wrist I and II, then do the next trackday, and all will become clear.

I have PDFs of the books if you want a copy, just PM me with your email address.

**R6_kid:Me** · 28th October 2008, 19:19

You should sign up for "Ride Right Ride Safe" - you're exactly the kind of person that will benefit from it.

**jrandom** · 28th October 2008, 19:24

I find a 2D visualisation the easiest way to start thinking about finding the center of mass (I think 'center of gravity' is an odd term).

Imagine a set of points on a plane. Say, a bunch of particles grouped together to form a solid body, although conceptually it doesn't matter whether they touch or form a 'cloud'.

The COM is the single point on that plane that has the lowest average distance to each of those points.

It should be intuitively clear (please don't make me prove it rigorously) that as you take your particles and stretch some of them out in one direction, that COM point will shift.

Extend that into three dimensions, and it then becomes clear that standing up on the footpegs and therefore moving your body mass further away from the existing 3D COM point will shift the 3D COM point upwards.

Therefore, moving your body around, regardless of the 'contact points' involved, can indeed change the COM of the bike-rider system, and the way it tips from side to side.

QED.

**beyond** · 28th October 2008, 19:35

Watch the rear braking thing in corners. Yeah it can work well but it's so easy to screw up and then you end up backing your bike into a corner which is good if that's what you want. Normally though, that's unexpected and causes people to shut off the throttle, the bike regrips and you get a nice highside with the resultant bonk on your block.

Cornering: relax your grip on the bars, keep your arms relaxed and drop the inside shoulder into the corner and everything else others have sai