sriram_r

Hi,

Could any one of experienced experts advice us about the risks of a alloy wheel when compared to that of a spoke wheel.

Nowadays almost all bikes invariably comes fit with alloy wheels and very recently i came across to witness a terrible road accident where i found the front alloy wheel missing only to realise later that it had broken to unidentifiable magnitude by breaking down in to pieces due to the force of the impact. the vehicle was a yamaha r15 and the entire front was smashed to the bone.

i also heard people saying alloy wheels are always risky when riding with pillion in high speeds and can no way match the safety of a spoked wheel..

If our fate is to live with the alloy wheels. what are ways we can safeguard ourselves so that our precious life is saved in case of an emergency..

Aryan

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Puneet1

haven't really heard of any disadvantages of alloys in our indian bike . in a accident alloy is bound to get damaged .whats the big deal ? you think spoke ones will be in very good condition after a crash

alloy rims allow you to put tubeless tyres that are safer than tubed ones in high speed riding .

"why spoke wheel safer for pillions" i didnt really understand . can you provide more info

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antz.bin

The alloys are designed to break in case of crash. In effect they act as crumple zone and absorb the impact.. similar to the bonnet of a car. Also they are safer as there is rarely fast air-loss due to puncture.. which at high speeds can get uncontrollable with tubed tyres..

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jd666

Alloy wheels in bikes ( because you dont have spoked wheels in cars anymore ), have the advantage that they dont need constant adjustment and alignment.

They come balanced, and you only need to balance it once the tyre is fitted.

Tubeless tyres can be used.

Alloys are stiffer than rims and spokes, so your handling is better, Also they weigh lesser.

Chances of rust eating away the spokes or affecting the strength of the wheel are negated, since alloys dont rust easy, or rather say rust at all.

Like pointed out above, they act like a crumple zone to absorb the impact. Saving your "precious lives in an emergency".

Specifically speaking, this was confirmed by an engineer in yamaha as well, that the Alloys in the R15/FZ series are designed to shatter on impact, so as to absorb the maximum possible energy.

And its not your fate, you can easily switch over to spoked rims as well if you want. they still sell in the market.

( goes and bangs head against wall )

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psr

Very True on ALL the points. Indian roads have more craters than the Moon. Even on highways sometimes I had found the road to be good while going and when returning back surprised by the road diggings that have come up. Only on toll roads the condition is better.

Pinaki

Cast ( Alloy ? ) wheels , once bent cannot be repaired back into shape , and must be replaced if damaged . It is almost imossible to balance a cast wheel post manufacture . Wire wheels are easily balanced by local (desi)workshops .

Cast wheels ( on Indian bikes ) are heavier than wire-spoke wheels , thus adding to the total weight of the bike . Moreover the weight of the wire spoke wheels are mainly in the outside ( i.e rims ) while the cast wheel has more distributed weight . This affects the balance of the bike while in motion and handling characteristics .

Cast wheels ( on indian bikes ) have integral brake-drums , and when worn out by the brake shoes , the whole rim has to be replaced , in wire wheels you can just replace the drum .

Cast wheel with tubeless tire will deflate immediately if the rim is bend by impact . Tubed spoke wheel will not deflate if the tube is intact . You can ride home on a bent spoke rim .

Wire-spoke wheel has a degree of flexibility that lets it absorb road bump
, working together with a pneumatic tire . Cast wheel has absolutely no flex and gives a stiff ride . I have personally felt this on road potholes .

I am not sure that on accident level impact , a cast wheel will absorb more of the impact energy than a wire spoke wheel , by deformation . The reverse is more likely , since the cast wheel is far more rigid than a spoke wheel , it should transmit more energy on impact than it absorbs by deformation .

Of course the alloy material used for such cast wheels do not rust , but they do corrode like all base metals , so they come painted to prevent this . I have my spoke rims painted insides with lead-oxide paint when new and they have never rusted since .

Pinaki .

psr

The wheels once bent should not be corrected and reused for safety reason. This will lead to wobble at speeds and may break on hitting a small pot hole.
All rims are heavier on the outer circumference.When the vehicle is in motion there is a centrifugal force which will make the wheel act like a gyro. A bike which can be maneuvered easily at low speeds cannot turn easily at high speeds.
Any tubed wheel act differently to a tubeless.
The flexibility of the spoke wheel is more than alloys. The flexibility of wheel is not good for stability,and the alloys cure this.Of course the ride is stiff, but the steering is positive and not vague.

It is expensive to replace alloys than a spoke wheel.

abhayshanu

I do not agree. If the rim is bent slightly it can be straightened out and so can a big bend, it is up to us whether to do that or no. I have personally done it.

Again, the bent wheel can be corrected, I have had it done and there are no problems after that, however I am replacing the rim right now as it has a big crack, this would be to much on the same rim, it will not be as safe that is why I am replacing it, however if it was a small bend or a medium one, I would have got it rectified and rode with it.

burnrubbernotursoul

Pardon my ignorance but pls quote me any manufacturer which uses wheels as crumble zone(except the yamaha in India) or a literature which mentions the same .world over high end cars and bikes are shifting towards mag wheels bcoz they are lighter and stronger than aluminium alloy wheels, aluminium wheels are more prone to breakage. the most dangerous thing that could ever happen to anyone is the wheels giving up on impact. why does car bonnet only acts as crumble zones and not its wheels along with the bonnet.

an example is when you hit a pothole at a good speed and your wheel breaks into small pieces, what will happen is that you will be thrown off and land on the road causing severe injuries. at the same time if the wheel gets bend there is atleast a possibility of steering the bike out of danger.


most serious injuries of bikers are mostly not due to the primary injuries (which means the injury due to first direct contact with an object) but due to secondary ones (ie when the biker lands up on the car or wall or road as he is flung off the bike.) the chances of secondary injury becomes more when the wheel gets crumbled .when the wheel collapses on impact the rider is more likely to be pulled into the impacting surface, coz the wheel will absorb the force and your momentum will directly take you in the path of the impact surface leading to more secondary injuries.


whereas if the wheel doesnt collapse the rider will be thrown off and there are good chances that he may clear the impacting surface.

in simple words if the bike collides with a car headon and wheels crumble the biker may hit the bonnet of the car and if the wheel doesnt crumble the rider may end on the windscreen or on the roof.

we talk about crumble zones in cars but we never bother to look at the fact that only the bonnet and the front are crumble zones and not the wheel or the passenger compartment .infact the passenger compartment is made very sturdy as well. besides the deceleration injuries are more serious in cars (whiplash , abdominal aorta tear etc etc )and that's why crumble zones to minimize the massive deceleration force acting which results in these injuries. additionally it adds to pedestrian safety as well. and that's not the case with bikes.

the reason why yamaha's wheel are crumbling is simple. for reducing weight of the wheel yamaha is making very thin alloys coupled with that they are very light as well .advantage of such light wheels are that the gyroscopic forces will be less which means less difficulty in changing direction,and the disadvantage is aluminium being more brittle than steel , they are more prone to breakage.

in simple language if aluminium wheels are a little thicker as found in most Indian bikes the wheel will bend in most cases and break if there is significant force but will be heavier. however if it is very thin like in yamahas the wheel becomes more brittle and breaks even at moderate force.but is very good for changing directions as the gyro force will be far lesser.

for me its nothing but weight losing measures by yamaha.thats why they provide those very thin tyres and alloys with R15 and in FZ when they had to upgrade the tyre they went for radial tyre which are around 30% lighter and stronger than normal tyres coupled with very light alloy wheels.

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