Reddit Reddit reviews Motorcycle Dynamics (Second Edition)

We found 9 Reddit comments about Motorcycle Dynamics (Second Edition). Here are the top ones, ranked by their Reddit score.

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Automotive
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Engineering & Transportation
Motorcycle Dynamics (Second Edition)
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9 Reddit comments about Motorcycle Dynamics (Second Edition):

u/myVisionIsAugment3d · 3 pointsr/motorcycles

There are literally books written on the subject
https://www.amazon.com/Motorcycle-Dynamics-Second-Vittore-Cossalter/dp/1430308613/ref=mp_s_a_1_3?keywords=motorcycle+dynamics&qid=1573548435&sprefix=motorcycle+dynamics&sr=8-3

edit: for more interesting topics bike-trike hybrid that cannot steer https://youtu.be/rNQdSfgJDNM

and bike that self balances without gyroscopic forces and trail https://youtu.be/YdtE3aIUhbU

u/1esproc · 3 pointsr/motorcycles

Nope. That's the whole point, vibrations, bad frame geometry, incorrect suspension settings, stuff like that can cause the rear end to do things like what's seen in the video. You should also consider that the front and rear tires are independent and of different radii, and can track independently which can be exacerbated based on surface, inflation and other factors

Check out a book called Motorcycle Dynamics. Just a cursory glance will show you motorcycles and the physics involved in a chassis are very complicated.

u/kin670 · 2 pointsr/motorcycles

You don't want the front wheel to lock up; this is why ABS is so popular. Also contact surface area does not affect traction. Weight and how the energy is transferred plays a more significant role in how a motorcycle stops.

Source

u/random_echo · 2 pointsr/Justrolledintotheshop

numbers come from this book, i'll scan you the page if you'r interested, maybe I did'nt got it right

http://www.amazon.fr/Motorcycle-Dynamics-Edition-Vittore-Cossalter/dp/1430308613

but we are not talking street application, the accident occured on a track, there is a lot more of grip, rear matters a lot less.

u/BendersCasino · 1 pointr/MechanicalEngineering

I ordered this book and it showed up yesterday - haven't gotten through much of it but it looks like it has most of the dynamic formulas you could ever need for a motorcycle.

u/canyonchaser · 1 pointr/motorcycles

> However, the use of the rear brake will not pull the back of the bike onto the ground.

You are so wrong. It's rotational mass. There is this great book that proves that you are totally wrong. It's called "Motorcycle Dynamics" and it even has the math equations to prove that applying the rear brake pulls the back of the bike down. The point is, the rear tire is far less likely to lift into the air if you are putting pressure on your rear brake pedal.

You can even try it yourself. Do a hard stop from about 45mph using just the front brake. Feel what the chassis does, then do a hard stop from the same speed using both brakes, you will feel the bike "squat" keeping the rear brake on the ground.

Of course the front brake can overwhelm these forces in the example you state. But that doesn't mean there is no advantage to learning how to use it correctly.

u/703Sumo · 1 pointr/MTB

> The BB height that varies by like 30 mm is going to be negated by you squatting down and bringing the CG lower. -you are completely wrong here. In my experience 5 mm of drop is very noticeable. 30 mm is massive. I lowered my bb last summer by swapping the linkage on my enduro, it dropped ~ 12 mm. Afterwards, I had to increase my tire pressure ~ 4 PSI, because I was rolling the tire off the rim on the same trail I'd been riding for 2 years from cornering that much harder. A lower BB allows you to corner harder all other things being equal - full stop. Even a small difference is VERY noticeable to an experienced rider.

Hah. Thats actually not to the bb being lower, its due to the fact that by dropping the rear, you have slackened your head angle and increased the geometric trail, which will make your bike feel much more planted in corners. Same reason why you get on a DH rig with a 63 head angle over your 66-68 trail bike, and it feels weird in the parking lot, but once you start going downhill you feel like you can just put it in corners and it stays there.

>Likewise, moving your weight back lets you corner much more aggressively because it creates stability in the front. -wrong again. If this were the case, Pro Riders would be way off the back of the bike in every corner - they aren't. Also, if you don't weight the front wheel you risk having it slide out. I'll concede that skilled riders will shift their weight front to back depending on the turn, but always shifting back is not the magic skill.

That is because the DH bikes that rail through corners already have a rearward weight bias.

And the point is that you can simply move your body weight back and forth to achieve cornering characteristics.

>Your example of riding with no hands is off - you don't understand the effect. But my first year physics knowledge fails me here - can some other internerd assist?

I 100% understand this effect, as my expertise and hobby is in suspension and chassi tuning for motorcycles.

The front fork/wheel assembly is at an angle known as the head angle. Because of this, when the handlebars are straight, the wheel is actually at the higher CG then it would be if you turned the bars. You can see this effect by yourself - take the bike, hold it upright on pavement, and lean it slightly one way or the other, and you will see the handlebars turn that direction as the front wheel "falls" in CG height to a lower position.

Likewise, if you lift the rear of the bike slightly and repeat the experiment, you will find that the handlebars don't turn as much, because the steeper head angle lessens this effect.

However, the head angle also puts the contact patch of the tire behind the steering axis, creating the trail effect. This makes the front tire act as a weathervane, and the effect increases at speed - rolling fast and turning a tire creates a higher slip angle, which creates a bigger force on the tire, which creates a higher force to straighten the bars.

The reason you can ride without hands is because of the interaction of those 2 events. When you lean your body, you lean the bike, and the handlebars want to turn in that direction, but the trail prevents that. And the slacker the head angle, the faster you have to go because the slacker head angle will make the bike fall over more, so you have to increase speed to make the trail effect cancel this.

And as you can probably imagine, putting more weight over the front tire effectively makes it "heavier", and thus increases the effect, since you are basically generating a handlebar yawing torque with the weight at the CG of the tire, which is affected by how much weight you put over it.

When you corner, the front end pretty much determines how the bike will corner. If you have the right amount of head angle and consequently trail, as you lean the bike, it settles into a steady state that feels planted, and you can rail through corners. If your head angle is steep and you have smaller trail value, the bike feels nervous, and you have to hold it in a high speed corner as opposed to the bike naturally settling there because of the reduced effect. And if you don't hold the bars in the right place, you start to either oversteer or understeer or even loose the front because you are exceeding the slip angle if you try to corner to hard.

>And moving the weight back also lets you brake harder with the front brake. -You move back as you brake to counter the force and not get sent over the bars. You are still weighting the front wheel pretty heavily when this happens.

Right, its the same thing as I am describing. If you are way forward, the front brake can generate enough torque to lift the rear end of the bike and send you over the bars, so you are limited by how much you can brake. If you weigh down the rear end of the bike, the torque required to flip you is much more, so you can apply much more front brake.

>I'm gonna skip your suspension stuff - I don't get your point.

The point is that if you wanna make judgement about linkages, you have to take the shock out of the equation. I agree that there are some cheap FS bikes with linkages that are worse than All mountain or Enduro bikes, but for all the better designed linkages, the goodness of the suspension is mostly due to the shock.

For example, take a Trance 3 from 2016, and the shock only has rebound adjustment. Someone riding it may say, "oh the rear dives to much under pedal power or it feels too stiff", all because the compression damping is internally set, and you can crank up the pressure or the rebound to make it pedal more efficiently but loose any suspension action.

But take that shock, swap with a Monarch RT3 Debonair, and suddenly you have the option of putting the bike in full lockout which makes it stiff but very pedal efficient, or full open which makes it super plush for fast descents over rough stuff. Likewise, you can add or remove spacers and modify the pressure and the bike can change from a trail machine that absorbs all bumps and lets you pedal uphil over roots without loosing traction, or it becomes a bike that can take drops and feels super planted when cornering.

>But design and construction are pretty darn important!

They are, and different frames weigh differently and some are stiffer which are noticeable. But none of this is enough to give a bike a rating in terms of being good or bad performer.

FYI, this is a book that will explain all dynamics in detail. Its very math intensive though, but there are plots that show all the effects I talk about.
https://www.amazon.com/Motorcycle-Dynamics-Second-Vittore-Cossalter/dp/1430308613

u/cajunboy_ · 1 pointr/MechanicalEngineering

Check out Motorcycle Dynamics by Vittore Cossalter..

Basically the RCVD of the motorcycle world. worth the cash if you're serious about it. ($45). i bought it about 5 years ago though and I don't remember it being that much back then but, who knows...

https://www.amazon.com/Motorcycle-Dynamics-Second-Vittore-Cossalter/dp/1430308613

Also, John Bradley - The Racing Motorcycle: A Technical Guide for Constructors, Volume 1 (v. 1)

haven't read this one personally but it's always been highly recommended.

u/xilanthro · 1 pointr/bikebuilders

Bikebuilds is a new site that catalogs custom bike builds. There are some similar builds indexed there.

As for reference, my experience was a little different because I was altering bikes for my own use in racing, so it's all really focused on handling, but still, you might find it useful: go-to books have been Bradley and Tony Foale.

That said, if you're really into understanding the implications of swing-arm lengths and rake angles, I have heard high praise for Cossalter's Motorcycle Dynamics, though I have not read it myself.