Lean angle vs G-force

**Cruisin' Craig** · 9th February 2008, 08:56

Originally Posted by Jantar

.....ACB is the right angle, not ABC.

AC is directed straight down, and CB represents the bike at some angle of lean. So ACB can't be a right angle unless the bike is horizontal.

**Jantar** · 9th February 2008, 10:49

Originally Posted by Cruisin' Craig

... So ACB can't be a right angle unless the bike is horizontal.

Of course it can. ACB = 90, ABC = 90-x, and BAC = x.

Also don't forget that the sum of All vectors must add to 0, otherwise the entire system will be unbalanced.

**Cruisin' Craig** · 9th February 2008, 11:26

Originally Posted by Jantar

Of course it can. ACB = 90, ABC = 90-x, and BAC = x.

Also don't forget that the sum of All vectors must add to 0, otherwise the entire system will be unbalanced.

Ah, I see. Quite right, ACB can be the 90 degree angle. If you do it that way the calculation ends up just the same except we have the bike leaning the other way.

I've also just done another calculation involving balancing torque moments and still get 45 degrees. I'll post that a bit later tonight once I've had a chance to check it to see what people think. Turns out it is a far easier calculation to do as well.

I'm still standing by my figure of 45 degrees, but I'm happy to reconsider if you can prove that the resultant acceleration vector being 26 degrees from vertical means that the lean angle must also be 26 degrees, as I believe they are not necessarily the same.

**cooneyr** · 9th February 2008, 12:14

I think you might be a little confused with all that analysis Cruisin' Craig. Like Jantar said AC is a component as is CD and the resultant vector is AD. Gravity is towards the earth's centre hence becomes one of the fixed axis of the system. We were also given that the 0.5 G is horizontal (meaning it is at 90 degrees to AC) hence the other fixed axis.

Think about what we actually know and are trying to work out not what we think we know and working backwards. Also dont worry about the algebra - we learn trig to make life easier and trig is less prone to errors.

Cheers R

**speedpro** · 9th February 2008, 13:37

Originally Posted by Cruisin' Craig

I've also just done another calculation involving balancing torque moments and still get 45 degrees..

Without being a genius, 45 deg would be obtained if both the vertical (gravity - 1G) vector and cornering forces vector were equal and therefore 1G as well. The resultant vector would be at 45deg and have a value of square root of 2. Simple trigonometry.

**Mikkel** · 9th February 2008, 13:39

Originally Posted by Jantar

Also don't forget that the sum of All vectors must add to 0, otherwise the entire system will be unbalanced.

Well, you don't want the sum of the vectors to be zero if you're trying to go around a corner now...

**madandy** · 9th February 2008, 14:06

This thread has enlightened me somewhat regarding the constant fuck ups Civil Engineers make .

**cooneyr** · 9th February 2008, 18:07

Originally Posted by madandy

This thread has enlightened me somewhat regarding the constant fuck ups Civil Engineers make .

Like this you mean?

Cheers R

**madandy** · 9th February 2008, 18:19

That's exactly right! Now they stand there for days 'discussing' how they fucked up so bad.
I have worked with mullet haired, jail tatt'd, toothless, chain smoking, compulsive cursing machine operators who make more sense and end up correcting the balls up's thier 'superior' Engineer supervisors create...
Now they argue about lean angles and come up with seemingly infinte reasons why they cannot agree.
Dont get me started on 'mechanical engineers'...

**dipshit** · 9th February 2008, 18:42

Originally Posted by madandy

This thread has enlightened me somewhat regarding the constant fuck ups Civil Engineers make .

haha... yes, they sit around with their calculators and slide rulers, but half the time haven't got a clue about reality in the real world.

**GSVR** · 9th February 2008, 19:10

I so like Google

http://www.msgroup.org/forums/mtt/to...p?TOPIC_ID=312

If your've got Microsoft Excel or the veiwer this is very good

http://www.msgroup.org/images/bike.xls

27 degrees is close enough.

**cooneyr** · 9th February 2008, 19:46

Originally Posted by madandy

..... I have worked with mullet haired, jail tatt'd, toothless, chain smoking, compulsive cursing machine operators who make more sense and end up correcting the balls up's thier 'superior' Engineer supervisors create......

Thats cause engineers never have perfect knowledge of a site and are always accountable to the accountants. Its easy to bitch about a design with the benefit of more detailed info - i.e. the hole in the ground that shows the subgrade is rubbish. You are right though most of those old toothless guys are bloody good to have on site - as long as you can work with them and not argue every 2 seconds.

Ever heard the saying "An engineer can do for $0.02 what any fool can do for $2."

Originally Posted by GSVR

I so like Google

http://www.msgroup.org/forums/mtt/to...p?TOPIC_ID=312

If your've got Microsoft Excel or the veiwer this is very good

http://www.msgroup.org/images/bike.xls

27 degrees is close enough.

And I though we were being geeky! That xls file is a bit excessive!

Cheers R

**speedpro** · 9th February 2008, 20:20

Yeah like the engineer who specified square roof penetrations on a job I was doing. My suggestion of specifying round holes so we could use a holesaw to make them hadn't been thought of. There were a few other "issues" as well. Me and a mate used to regularly pick holes in an engineer mates designs for all sorts of things, mainly his self designed sports car rear-end. ZZR1100 engined so kind of relevent on a KB thread. maybe. He just about always came round to our idea, after say all the teeth were ripped off both sprockets.