R-series

Mod Message: POSTED BY OLD FOX and converted into a new topic for discussing Handlebars and Steering Torque:


I dont mean to interrupt the classification, but now adays non of the classes is defined. there is a fine line between sports, cruisers,street etc. and all other classes of motorcycles which the bikes that are coming up worldwide tend to remove easily.
companies are coming up with designes which cannot be said strictly sports or strictly street sports or street cruisers.

where V-rod and V-max come in the dragsters category..the B-king...being of the similar origin is not a dragster more than it is a naked street bike. I thing the MT-01 is more closer to the B-king than the V-max.
Dragsters: are cruisers which have a slighly sporty sitting position for fast riding.

Wanted to correct the statement here(the above one in bold)...along with the rake angle..the wheelbase has a major part to play in flickability of a bike. Larger rake angle is not exactly unstable...in another way you can say a shorter angle gives more handling ability than larger one. cruisers have a higher rake angle and due to the dimensions of the bike,they are more stable at higher speeds.
its not that "Sportsbikes cannot turn handle beyond certain limit " but they are not meant to turn the handle too much...the reason is not putting up the fairing on the bike...but they are made to turn at higher speeds...which requires banking(or leaning) more than the turning of the handle...so they just dont have it because they dont require them.
and compared to street bike...the handle doesnt turn over a larger angle..its just that since the handle bars are far off wider...so it looks as if the street bike handle covers a larger angle of rotation.
apart from that the different in the turning of the handle is not as much as it looks to be.

one thing i would like to highlight is that ...the design of a bike starts from what it is going to be used for. that starts off the type of engine it requires. then a similar chassis required to hold the engine...and then the body work.
the final bike that we all come across is actually a mix between the actual design and the practical model. though intial design greatly influences the outcome...its never the actual thing that comes into production.

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satyenpoojary

This is good stuff... bookmarking this now!

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kaynmantis

Take a look at the illustration below. Been wondering about this how angle of rake can change characteristics of bike. I understand that more angle(or is that less angle. Am no geometry expert. Anyway the idea is when rake is angled further away from perpendicular 90 degrees) will increase wheelbase. Closer to 90 degs. will decrease wheelbase and hence alter characteristics. This I know and is NOT my question.

My question is, since different angle in rake will make the front tyre lean at an angle against the road when handle is turned. Meaning, as angle moves further away from 90 degs., the front tyre will lean more and more and vice versa. In what manner does this affect the characteristic of the bike?

See picture below. It will illustrate my question.

Attached Thumbnails

 

satyenpoojary

I am no expert but the first two things that came in my mind were the first is the RTR, and the second is the avenger...
Flickability vs Cruising..

Is that right?

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R-series

Good question..would love to answer this one.
first..lets consider the first picture...when you lean the bike left or right...it directly affects the tyre leaning ( here the "centre of rotation", would be the point of contact between the tyre and the road) as it is more closer to perpendicular. In rotational motion physics...the force acted upon a rotating body(the tyre in this case) is total force acted upon the perpendicular from the centre of rotation and not only the magnitude of the force .
In the picture given below...if rake angle(A) is more closer to the perpendicular..thus small force is required to rotate the wheel by angle B.


Similarly in the second case (larger rake angle)
since the rake angle is more and inturn distance from the normal is more, the force required to rotate the wheel by angle B is more.

This is why shorter rake angles respond more quickly (as less movement is required to produce a large effect) than compared to larger rake angle motorcycles(where more movement is required to produce the same effect).

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kaynmantis

You can say that. Take the case of the second example (cruiser). If you are taking a turn and lean the bike, the front tyres will be leaning much more than the first example. Not that you would do some knee scraping stuff on a cruiser. Just wondering on the technical aspects and curious as to how much importance is given to it while designing a bike in relation to its handling characteristics. Would a couple of millimeters in a racing sports bike make a difference?

Another interesting thing is how the rear suspension also alters the wheelbase when the suspension goes up and down and can affect handling. Heard about manufacturers design some bike to make wheelbase remain constant during suspension play.

R-series

its not only the banking of the motorcycle that decides the turning speed.
30 degree banking on a shorter wheelbase bike covers a larger angle than a 30 degree banking larger wheelbase bike. both travelling at the same speed and in the same interval of time.

Consider the pitcure below. a shorter wheelbase bike following AB path at say 50 kmph at 30 degree banking and a larger wheelbase bike following path CD at same speed(50kmph) and same 30 degree of banking.


since both are at same speed but the distance AB is less than CD...thus the shorter wheelbase bike will cover the same angle in lesser time( though travelling at the same speed).
What im emphasising on is that its only only the banking of a few degrees that is making the difference here..but its actually the wheel base.
So a few degree banking gives a faster turning in shorter wheelbase bikes than it does in larger wheelbase bikes.

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kaynmantis

Agreed, however as I illustrate im my diagram. A steep angled rake will make the front wheel lean more than a perpendicular one. So lets say, bike is leaning at 45 degs this means rear wheel is leaning at 45 degrees, but front wheels will be leaning more for example 35 degs when turning. Where as if the rake is perpendicular, the leaning of front tyres may more or less be close to 45 degs in the same situation. In effect, the steep rake will have a greater chance of sliding its front wheels. Is my reasoning sound so far ?

R-series

Agreed , no doubts.
But what I caught in one of the post was "does a few degrees of banking make much difference"
compared to the handling part...there is more than just the banking angle...which is why a few degrees on sports bike is quite alot compared to that on a cruiser.
But are you trying to just say that steeper(larger) rake angle is more prone to sliding than the shorter one..?

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inflammable

R Series - better denotion for that would be Turning Radius.

- Street bikes have smaller turing radius. Which makes them flickable in tight spots. The sitting stance is more upright which gives you the confidence to easily take tight turns at slow speeds.

- Sports bikes & cruisers have large turning radius..

- However in case of sports bikes the handle movement is restricted.. which causes the large turning radius. Another reason for keeping a restricted Handle movement is.. the rear set footpegs.. which causes more sportier stance which restricts the body movement under tight turns on slow speeds.
Ok.. look at Yamaha R1 pic... imagine yourself sitting on yamaha R1.. presuming the handle movement is not restricted (more handle movement).. and you are sitting in a sporty stance. With both legs up on footpegs.. Can you take a tight U turn without you putting your feet on ground? It would be tough doing that. But on street bike its easy..as Riding stance is more upright.

On a sports bike.. you are laying on the bike. On street bike you are sitting on the bike.

- Where as Cruisers despite of having large handle movement.. have large turning radius due to the longer wheelbase.

Nitro correct me.. if i am wrong anywhere.

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