Handle bar end weights

[redken1]

And there was me thinking they were there to keep the handle bar grips on. :P ;D

[Swanny]

I thought they were to protect your grips in case you bumped against a wall :P ;D

[gibbo]

So, where does the vibration actually resonate from? Is it an unbalanced crankshaft, bad engine management, tuning, design etc. Needs fixing whatever it is. :-/

[Snowy]

So, where does the vibration actually resonate from? Is it an unbalanced crankshaft, bad engine management, tuning, design etc. Needs fixing whatever it is. :-/

I work on the basis that if BMW can't sort it then I certainly can't. Both bikes are well known for it and have been for decades. The trick is to ride faster

[Scotty]

An internal combustion engine is full of large heavy components that rotate or reciprocate - that's where the vibration emanates from - some engines are more inherently balanced than others - normal in-line 4 cylinder engines have perfect primary balance but imperfect secondary balance and give high frequency vibrations. (Cross-plane crank R1s lose the primary balance and have to run an additional balance shaft (that saps power) to compensate for it) Generally the fewer cylinders, the more vibration they make. Twins can be good or bad depending on the engine configuration; the best being BMW Boxers and 90º Vs like Ducatis, the worst being 45ºVs (Harleys) and 360º twins (old British bikes). Older singles are the worst of the lot... The smoothest bike engine is a 6-cylinder with 120º crank throws (Goldwing, Honda CBX, Kawasaki Z1300 etc.)

Getting to the techy bit... The natural frequency (f_n) of an object is calculated by the following formula: f_n = [ch8730](k/m) which means that the frequency at which the object will resonate (its natural frequency) is the square root of its stiffness divided by its mass. By adding mass (a weight) to the handlebar, the Engineers reduce its natural frequency to one that is less likely to be obtrusive during use.

Bike designers are extremely cost-conscious as they have accountants breathing down their necks constantly - Bar end weights are not aesthetically pleasing and couldn't be justified from that perspective. They're not for styling, they have a function. To engineer all vibration out of an internal combustion engine is possible, but not justifiable either economically or from the performance perspective. Car engines are isolated from the chassis by rubber mountings, on bikes we have to make do with bar end weights and rubber-mounted footrests in some cases...

[Nelly]

An internal combustion engine is full of large heavy components that rotate or reciprocate - that's where the vibration emanates from - some engines are more inherently balanced than others - normal in-line 4 cylinder engines have perfect primary balance but imperfect secondary balance and give high frequency vibrations. (Cross-plane crank R1s lose the primary balance and have to run an additional balance shaft (that saps power) to compensate for it) Generally the fewer cylinders, the more vibration they make. Twins can be good or bad depending on the engine configuration; the best being BMW Boxers and 90º Vs like Ducatis, the worst being 45ºVs (Harleys) and 360º twins (old British bikes). Older singles are the worst of the lot... The smoothest bike engine is a 6-cylinder with 120º crank throws (Goldwing, Honda CBX, Kawasaki Z1300 etc.)

Getting to the techy bit... The natural frequency (f_n) of an object is calculated by the following formula: f_n = [ch8730](k/m) which means that the frequency at which the object will resonate (its natural frequency) is the square root of its stiffness divided by its mass. By adding mass (a weight) to the handlebar, the Engineers reduce its natural frequency to one that is less likely to be obtrusive during use.

Bike designers are extremely cost-conscious as they have accountants breathing down their necks constantly - Bar end weights are not aesthetically pleasing and couldn't be justified from that perspective. They're not for styling, they have a function. To engineer all vibration out of an internal combustion engine is possible, but not justifiable either economically or from the performance perspective. Car engines are isolated from the chassis by rubber mountings, on bikes we have to make do with bar end weights and rubber-mounted footrests in some cases...

Blimey scotty! You swallowed a haynes manual?

[Scotty]

Nah mate, you wouldn't get anything that technical in a Haynes Manual... it's about the easiest formula I learnt at Uni

[Jon_W]

How did you get the square root symbol and the sub script????

Indeed, you do leave uni with a few thing embedded. The natural frequency equation is one of them.

However, you need to consider transmissability in your equations as the bars are not directly coupled to the engine.