Rotational stress/strain. Any engineers?

[stinkwheel]

Right, on my quest for cast wheels for my KLE, I have a question.

If I were to fit a 3-spoke alloy front wheel with 'swept back' spokes in the bike flipped through 180 degrees (so the brake disc is on the correct side), is the braking force through the wheel going to snap the spokes because it is working the wrong way round?

I know the mass of the bike will be working vertically through the spoke anyway so this should make no difference, but there must be a fair twisting force between the hub and the rim when you apply the brakes. I suspect the 'sweep' on the wheel is nothing other than a styling cue but I don't want to hit the brakes and find the wheel collapses under me

It maybe doesn't even work like that?

I did a picture. A is how the wheel is designed to work. B is what I am proposing.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

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Sorry I can't offer any advice but just to say from the title I'm disappointed this thread isn't about kinky sex on a fairground ride

Just my thought process

FWIW IMO I would have thought some lateral forces would also come into play. Hope you get an answer.
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[Suzuki]

You are correct in thinking that the sweeping design of the spokes is to give additional strength to withstand the forces applied during brakeing.

I would advise against flipping the wheel round.

A number of large trikes use a motorcycle rear wheel for the front wheel, but have it flipped in reverse. This is because they're designed to withstand the forces of accelleration. When used as a front wheel, they have to be reversed so that they withstand the forces of brakeing.

However, for an answer you can rely on... contact the manufacturer.

[mchaggis]

From the looks of it, braking with the wheel the normal way round would put a compressive load directly down the line of the spokes as the leading edge of the spoke is tangential to the hub. The other way around, I would have to say that the line of action of the force would be across the section of the spoke as the leading edge of the spoke points towards the centre of the hub.

Sorry if that doesn't sound very clear, but basically what I'm saying is that the normal way round will produce compressive loading of the spokes, whereas the reverse way round will create a bending moment at the spoke/ hub interface.

Anyone please feel free to correct me if I'm wrong. Hopefully I am.

However, whether it would actually be a problem is another question altogether.
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[Korn]

Other people have already nailed down the physics, however a point to remember is that (unless you're using super lightweight ultra exotic wheels straight from motoGP racing) they are likely to be over engineered to such a degree that any extra stress from your application will still be well within what they can safely tolerate... IMHO.
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[mr.z]

^ what korn said, only way to find out iwoudl be to try it and monitor it VERY carefully check for hairline fractures (uv light, soloution of some kind + magnifying glass apparenty) after giveing it a bit of stick, can't see it just snaping in half without warning, but its stil a risk... front wheel disintergrateing at 100 wouldn't be allot of fun

Somebody with pro engineer, 100% certainty of the material being used and ALLOT of time (or just hapen to have the model drawn up allready) could tell you if the load is going to be sustained or not, i dont even know how to use it so can't be of much help there

Normal spoked wheels are a pain in the ass to clean e.t.c. but they can be repaired if the sheeit really hits the fan, all you need do is take spare spokes and a spoke spanner thing...
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>RidingSkills<->Tech Tips<->MyBikes<

[stinkwheel]

Cheers for the input guys. I think I will have to stick with either finding a cast wheel with the disc on the left hand side, a symmetrical wheel with the disc on either side or if it comes to it, get a spare standard wheel and have a 17" rim built on to it.

Just kind of liked the idea of having cast wheels, no good reason for it really, I am aware that a spoked wheel will be stronger. I'll see what they have in the breakers tomorrow, you never know, I might even land up with a comstar

Thanks again.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[cagiva gezzer]

https://www.bikepics.com/pics/pics/aprilia-rs125-99-bikepics-411482.jpg

Saw this and thought of you.
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"because one stroke isnt enough and four strokes waste two"

[Lee_367]

Is that out of an RS125? What happened to do that?
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[stinkwheel]

[no_shad]

Head first into a car. Only suffered broken thumbs.
Full Story Here

[Big Pete]

Stinkwheel, I'm a consultant stress engineer by trade, I spend all day doing finite element analysis of bits of planes etc.

So, flip the wheel if you want, normal riding loads are miniscule compared to crash loads, and wheels are massively overengineered anyway, given that I (20 stone of pure muscle ) could run that rim into a kerp at 30mph and expect no significant damage, you arent going to have any problems. The only theoretical risk is fatigue cracking, as ally has a low fatigue strength. However, the driving stresses are so low as to give an effectively infinite life.
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[stinkwheel]

Cheers Pete

That makes my life considerably easier and cheaper since I already own that wheel and it is in a scrap bike. As such it also comes with a tyre, brake disc, spacers and speedo drive (which may or may not work). It is also the mate of the rear wheel I am going to use.

Oh and congratulations on oficialy becoming The Garage of Power®
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[map]

[iCraig]