Tour de France 2009 - A Master Class in Down Hill

daviesee

dilemna wrote:

daviesee wrote:

What was unclear was using the phrase "keep centred over the bike". This read as keeping the bike upright during cornering. Due to centrifugal forces this cannot be good advice as the faster you are going the more you have to lean over to combat the centrifugal forces.

There comes a point at high speed where the tyres will lose grip on the side walls if you lean over any further but centrifugal forces will have you understeering. At this point dropping a knee will lower your centre of gravity without affecting the tyres contact point which will reduce the effect of understeer.

There is no such thing as a centrifugal force. You are confusing a machine known as the centrifuge with a physical force. I think you mean the centripetal force which is the force that a body is exerting toward the centre of a circle about which it is turning ie a bend or carousel.

Eh, sorry Dilemna but no. I do mean centrifugal force where a rotating motion forces the body away from the centre. You lean into the corner using centripetal forces to counteract the centrifugal force - I think :?

http://en.wikipedia.org/wiki/Centrifugal_force

PS Cycles can indeed understeer as I found out to my surprise one morning by going round a tight bend and found myself unable to stay on the left hand lane :shock:
White van man coming the other way was equally shocked and I dread to think what he was shouting as I bailed to the ditch :oops:

Anyway; Some guys are silky smooth, some are hashy and the rest are like me - scared

Jason Currie

There is no such thing as a centrifugal force.
The sensation of such is merely your body try ing to obey Newton's 1st Law, ie trying to continue in a straight line at a constant speed.
You need to hold on to a roundabout (for example) not to prevent yourself from being 'thrown' off by centrifugal force, but to provide the centripetal force necessary to produce circular motion.

I think the gyroscope effect of the wheels has a big part to play in cornering at speed. Ever seen the demo of a person sitting on a swivel chair with a spinning flywheel? When the wheel is tilted over the person spins. The same thing happens when the wheels of your bike are tilted over, the bike turns even though you barely moved the bars.

All of which has nothing to do with dropping a knee, of course.

Jase

nicensleazy

I have always applied to the principles of Road Craft which has served me well in cycling!

dilemna

daviesee wrote:

dilemna wrote:

daviesee wrote:

What was unclear was using the phrase "keep centred over the bike". This read as keeping the bike upright during cornering. Due to centrifugal forces this cannot be good advice as the faster you are going the more you have to lean over to combat the centrifugal forces.

There comes a point at high speed where the tyres will lose grip on the side walls if you lean over any further but centrifugal forces will have you understeering. At this point dropping a knee will lower your centre of gravity without affecting the tyres contact point which will reduce the effect of understeer.

There is no such thing as a centrifugal force. You are confusing a machine known as the centrifuge with a physical force. I think you mean the centripetal force which is the force that a body is exerting toward the centre of a circle about which it is turning ie a bend or carousel.

Eh, sorry Dilemna but no. I do mean centrifugal force where a rotating motion forces the body away from the centre. You lean into the corner using centripetal forces to counteract the centrifugal force - I think :?

http://en.wikipedia.org/wiki/Centrifugal_force

No you ARE wrong. No need to apologise for your ignorance. You obviously haven't studied pyhsics. This is standard A-level material. Don't believe all that appears on Wickedpedia :roll: .

daviesee

Well, they say that you learn something new every day.

As I have now learned something does that mean that I can switch the brain off now? It hurts

PS I did do physics. Unfortunately it was 33 years ago and is now buried very deep under all the useless stuff I have learned since :shock:

nicensleazy

Sorted!

nicensleazy

Its back

http://www.youtube.com/watch?v=j_wEG2RN ... L&index=11

dbb

and still a great piece of footage!