Designing stuff

[Marmoot]

Could you explain that in a bit more detail?
I don't understand how 4-spoke wheels would be any worse.

Long explanation....might bore some people here.
But I could do physics tutorial. I charge by the hour

Anyhow, that is also the reason why you don't see 4-spoke wheels too much out there.

[erik]

Long explanation....might bore some people here.
But I could do physics tutorial. I charge by the hour

Anyhow, that is also the reason why you don't see 4-spoke wheels too much out there.

 

[juzzer]

Long explanation....might bore some people here.
But I could do physics tutorial. I charge by the hour

Anyhow, that is also the reason why you don't see 4-spoke wheels too much out there.

Bloody Honda riders are smart a Hail Prof Marmoot

[thealmightytaco]

We had solidworks at Uni (mech eng degree at Canterbury) and we've just bought the latest at work, Solidworks 2005. 2006 should be here by now but they havent sent it to us yet. It can do some mad stuff, and after you've made the model you just hit the drawing button, and presto add all the views and dimensions you want, it's fantastic. It's got FEA now too, so you can hold your model here and apply a force here and see if it's strong enough. But to buy the proper one it's between $9000 and $18000 depending on how many features you want, and then $3000 a year to get the latest as it comes out, subscription style. Or the student version is $300. Gotta do a course though, there's one at Manukau for $400? Or there's piracy, if you can find a version.

And for 4 spoke wheels, worst case (which'll happen 4 times a revolution) they'll wobble 'cause you've essentially only got 2 planks supporting the rim against non-axial torsion (twisting the rim around the axle is if you're on the side, one hand on top of wheel, other underneath rocking it back and forth, like if checking the bearings, but imagine it so strong the rim is rolling over), whereas with 3,5 or 6 you've got more planks to resist that wobble more often type thing. Stiffer.

Hopefully that made a lick of sense, it's too late to recheck.

[Brian d marge]

And for 4 spoke wheels, worst case (which'll happen 4 times a revolution) they'll wobble 'cause you've essentially only got 2 planks supporting the rim against non-axial torsion (twisting the rim around the axle is if you're on the side, one hand on top of wheel, other underneath rocking it back and forth, like if checking the bearings, but imagine it so strong the rim is rolling over), whereas with 3,5 or 6 you've got more planks to resist that wobble more often type thing. Stiffer.

Hopefully that made a lick of sense, it's too late to recheck.

Made good sence though I will have to think about that one....Sounds plausable

will be home from work soon...and I am indeed looking forward to alkyholll


As for finite analysis ...would be very nice ,,,,,,buy oh look at that price ...

Stephen

[Marmoot]

Bloody Honda riders are smart a Hail Prof Marmoot

Aye brother!
That's why we chose Honda....coz we is smart aye!

[erik]

And for 4 spoke wheels, worst case (which'll happen 4 times a revolution) they'll wobble 'cause you've essentially only got 2 planks supporting the rim against non-axial torsion (twisting the rim around the axle is if you're on the side, one hand on top of wheel, other underneath rocking it back and forth, like if checking the bearings, but imagine it so strong the rim is rolling over), whereas with 3,5 or 6 you've got more planks to resist that wobble more often type thing. Stiffer.

Hopefully that made a lick of sense, it's too late to recheck.

Hmm. The explanation that it is non-axial torsion we are considering clears things up a bit. By "plank" you mean a single spoke?

Say the the spokes on a 4-spoke wheel were aligned vertically and horizontally, all 4 spokes would resist non-axial torsion: the vertical spokes would be subject to bending and the horizontal spokes would be subject to torsion.

In a 3-spoke wheel with 1 spoke pointing vertically down, the bottom spoke would be subject to bending and the top spokes would be subject to a combination of torsion and bending.

It is difficult to see how the 3-spoke wheel is any better than the 4-spoke wheel.

I'd guess that the choice of a 3-spoke over 4-spoke wheel is mostly an aesthetic consideration.

I had a look, couldn't find any photos of 4-spoke motorcycle wheels, but did find mention of them for BMWs here.
There are 4-spoke bicycle wheels available (see here )which would be subject to similar forces except on a smaller scale than motorcycle wheels. Perhaps on a bicycle using 4 spokes reduces the length of rim unsupported by spokes, maybe a 3-spoke wheel would need a heavier rim?

[TwoSeven]

I do all my concepts and base drawings on paper. Since I cant draw, I have found taking a picture of another bike, printing it on the color printer, then putting a sheet of paper over the top, so I can trace and modify the outline, to be a good cheats way. Cant be bothered with faffing about on a computer program until I have a pretty good idea what I want to do. By then I've usually lost interest in it

Couple of things about the design of wheels that might be usefull. The rim on modern wheen should have several angles across it for stiffness both for sidways movemement and for impact resistance. There is also a special design on the bead to hold the tire.

On the old F2, the axel is narrower than the rim aby about 30%, with the thick end of the spokes taking most of this up (6 spokes) and the thin end on the rim only using about 20% space. Spokes are triangluar in shape and turned sideways (easy to clean).

Also, dont forget the design of the cush drive on the rear rim, and both rims require room for a spacer each side of the wheel, especially the rear wheel as its used to align the wheel in the bike given the a set rear sprocket distance and chain alignment.

[avgas]

Aye brother!
That's why we chose Honda....coz we is smart aye!

Funny u mention that - it seem all the obsessively smart people i meet buy diHatsu Charades????

[Brian d marge]

three spoke 4 spoke wheels ....Efficiency of design ...as pointed out before about the plank ....yes true but the three spoke is more efficient design with regards to strength /wieght ...you dont get any more stiffness for the increase in wieght if you add a 4th spoke .
5 spokes you can make the spoke thinner which may make thwheel more efficient again ...moving or changing it Radius of gyration ( I mean Rossi does want it to turn into the corners!!!)


Stephen

[nudemetalz]

Upon hearing all of this discussion with the downfalls of a 4-spoke wheel design, it's interesting that Yamaha have this on their MT-0S concept bike.

[Eurodave]

One word describes that new Yamaha YUMMY!!!

[Brian d marge]

It also has wave rotors as well , I suspect more for asthetic reasons than any other .
Tis a very nice looking bike ...almost Buell like ........

Stephen

[Milky]

Solidworks isn't the most powerfull design tool out there. I also got PCT pro desktop and although more powerfull is not as user friendly

I agree with you there. Pro-D is a toy compared to Wildfire 2 though (Pro Engineer) If the license for solidworks is nigh on 13k+ upkeep, I imagine that UoA is spending hundreds of thousands on ProE licenses for the mechanical dept.
Anyone else use ProE out there? I have been for about a year, and only just scratched the surface of it's capabilities. A couple of 3rd year mech friends were doing a CNC routing project for Design in ProE... Real impressive stuff.

[thealmightytaco]

three spoke 4 spoke wheels ....Efficiency of design ...as pointed out before about the plank ....yes true but the three spoke is more efficient design with regards to strength /wieght ...you dont get any more stiffness for the increase in wieght if you add a 4th spoke .
5 spokes you can make the spoke thinner which may make thwheel more efficient again ...moving or changing it Radius of gyration ( I mean Rossi does want it to turn into the corners!!!)

Precisely, the 4 spoke can be designed to achieve the required stiffness but it'd be heavier than the 3 or 5 spoke, hence obsolete. Not that I've done the calcs on this myself, makes sense thinkin' about it conceptually but everything can always be proven wrong.