Riding up and down hill

[Motofool]

Originally Posted by Misti

Many of you have said that you roll on the gas while going up the hill but what are you supposed to do with the throttle while you are riding down hill? Do you coast? Do you maintain, do you roll on?

Originally Posted by choneofakind

Because you still need to transfer weight to the back wheel.

The acceleration you experience from going downhill is one that does not cause weight shift. It is the acceleration experienced uniformly by the mass of you+machine as you both go down the hill........

Cornering or going straight?

No all road grades are the same:
https://en.wikipedia.org/wiki/Grade_%28slope%29

Downhill like this?

[choneofakind]

cornering


I understand how grades are determined.

[allanoue]

I live in a very hilly area 15 miles from a ski area with many steep curves and I can not think of one corner I would coast though.

However: there is one road I drove down in a car that I was on the breaks the whole way down, I think I would have done the same on a bike but IDK.

Anyone go down this road on a bike?

[snot]

Originally Posted by allanoue

I live in a very hilly area 15 miles from a ski area with many steep curves and I can not think of one corner I would coast though.

However: there is one road I drove down in a car that I was on the breaks the whole way down, I think I would have done the same on a bike but IDK.

Anyone go down this road on a bike?

that looks like fun!

[Misti]

Originally Posted by choneofakind

Because you still need to transfer weight to the back wheel.

The acceleration you experience from going downhill is one that does not cause weight shift. It is the acceleration experienced uniformly by the mass of you+machine as you both go down the hill.

Because of this, you need to use the throttle accelerate the machine IN ADDITION TO this downhill acceleration to get proper weight transfer. Without the weight transfer to the back wheel, you're loading the front wheel heavily and are asking a lot of your front tire.

Many riders only slow as much as they do on flat ground when setting up entry speed for downhill curves. If they do the proper roll-on, they end up at a much higher corner speed and exit speed than they planned... then crash. If they skip the proper roll-on, they ask too much of the front tire... then crash. If they're lucky enough to not have crashed, they've at least scared themselves a little and/or lost control of lane position.


Rule of thumb for all corners for me when riding unfamiliar roads or under unfamiliar conditions: set entry speeds a little lower than normal, keep it wide, turn in late, and rail the throttle, as applicable. This works for uphill, downhill, flat, new roads, familiar roads, bad weather, etc. It's always better in my mind to take a corner a little slow than it is to scare the poop out of myself and/or bin it.

Excellent.

Originally Posted by allanoue

I live in a very hilly area 15 miles from a ski area with many steep curves and I can not think of one corner I would coast though.

However: there is one road I drove down in a car that I was on the breaks the whole way down, I think I would have done the same on a bike but IDK.

Anyone go down this road on a bike?

Lombard street in San Fran. I rode down that on my 2001 Kawasaki ZX6r :dance cool:

Super fun. And of course I had perfect throttle control all the way down, rolling on the gas and all.. lol! Actually I think I was on the brakes the entire way down as there was a non stop line up of cars.

[Alex]

Originally Posted by allanoue

Anyone go down this road on a bike?

Fun for pics. Not so fun for riding. It's almost always packed, so you're trying to keep upright at a walking pace while taking full lock corners downhill.

[akima]

@choneofakind
@Misti

Originally Posted by choneofakind

Your oil pressure varies greatly based on engine speed.

So let's say you're coasting down a hill at 55 mph with the clutch pulled. Your gearbox is spinning like mad. Your engine is idling at 1500 rpm, when it normally would be running 6000-ish rpm at that speed.

Seeing the potential for issue?

I learned something new! I'd never previously thought about which side of the clutch plates the gearbox sits on. I've also never thought about how a disconnected clutch effects the oiling of an engine when the bike is moving.

I'm now thinking about the -- recently popularized by vloggers -- sport of down-hill, super-sport, neutral races!

Link to original page on YouTube.

Are these guys all doing a bit of damage to their gearbox?

Would the damage be worse if the bike went from being off (for an extended period) to coasting in neutral like this? Presumably if the engine had been on for a while there would be more lubrication in the gearbox. (I have only a very basic understanding of motorcycle engines, so I might be missing something here).

Also: There's something really special and satisfying about coasting down hill! Good feeling.

Originally Posted by Misti

Many of you have said that you roll on the gas while going up the hill but what are you supposed to do with the throttle while you are riding down hill? Do you coast? Do you maintain, do you roll on?

If one of the main points of rolling on through a turn on a flat, is to transfer most of the weight and force to the rear tyre, then presumably it's equally if not more important to roll-on in a turn going down hill. While corning down-hill, I imagine that the front tyre will be under more force than if you were cornering on a flat. This would be because more of the weight of the entire bike will be shifted onto the front tyre on account of the angle of the bike on the z-axis. So if anything, I'm guessing you need to slow down far more than you would for an equivalent corner on a flat so that:
1. you can accelerate even harder through the turn as to transfer the proper amount of force away from the front tyre and onto the rear tyre.
2. so that your entry speed is slower than for the same corner on a flat, as to account for the fact that the bike will accelerate through the turn much quicker than on a flat: the pull of gravity + the additional acceleration generated from point 1.)

(obviously I'm talking about riding close to the traction limit. If you're puttering through a turn well within the traction limit, you can bounce up and down on the suspension springs, joyfully saying "boing boing boing" in your helmet, while simultaneously chirping the brakes... and you'll maintain traction, or at least get it back almost as quick as you loose it.)

Does my reasoning hold-up?

[dcj13]

Hmm. I thought the gears were dipped-in-oil splash-fed.

[choneofakind]

Akima, It's the internet and I'm just another poster. There's as good a chance that I'm wrong as there is that I'm right.

I remember there was a post a year or two ago that talked about towing a motorcycle with the rear wheel rolling on the ground, and there was a very similar discussion to this one. Consensus was to not roll the back wheel like that without the engine running, even in neutral.

I bet once or twice doesn't hurt anything. I'd rather not do it regularly though; not something I'd do every ride on hills.

[akima]

^ you're not just another person on the internet. You're an engineer who has successfully changed a carb-ninjette into a fi-ninjette. I defer to your better judgement

Also: you're the 3rd person on the internet I asked. I asked these guys and they came up blank:

confused-cat.jpg

[choneofakind]

Lol. It was a kit. The impressive one is Greg737. He did his fuel injection setup from scratch.

[csmith12]

Originally Posted by akima

Does my reasoning hold-up?

[toEleven]

I'm now thinking about the -- recently popularized by vloggers -- sport of down-hill, super-sport, neutral races!

vloggers? I'm surprised the popularity isn't attributed to, say, "The Fine Art of Braking" which seems to be attributed to Keith Code. I hear he has a solid readership, and he definitely beat any youtuber to the punch.

[Misti]

Originally Posted by akima

@choneofakind
@Misti

If one of the main points of rolling on through a turn on a flat, is to transfer most of the weight and force to the rear tyre, then presumably it's equally if not more important to roll-on in a turn going down hill. While corning down-hill, I imagine that the front tyre will be under more force than if you were cornering on a flat. This would be because more of the weight of the entire bike will be shifted onto the front tyre on account of the angle of the bike on the z-axis. So if anything, I'm guessing you need to slow down far more than you would for an equivalent corner on a flat so that:
1. you can accelerate even harder through the turn as to transfer the proper amount of force away from the front tyre and onto the rear tyre.
2. so that your entry speed is slower than for the same corner on a flat, as to account for the fact that the bike will accelerate through the turn much quicker than on a flat: the pull of gravity + the additional acceleration generated from point 1.)

(obviously I'm talking about riding close to the traction limit. If you're puttering through a turn well within the traction limit, you can bounce up and down on the suspension springs, joyfully saying "boing boing boing" in your helmet, while simultaneously chirping the brakes... and you'll maintain traction, or at least get it back almost as quick as you loose it.)

Does my reasoning hold-up?

Yes, yes. Exactly

And Keith Code developed the concept of the No Brakes exercises when he used to have coasting races with his friends many moons ago. The idea of racing in neutral is no new concept....and it's a great way to get a real grasp of perception of speed when you aren't using any form of brakes.