Any mechanical engineers in the haus? Help requested!

[Dare]

I'm designing a spokeless bike for a class in CAD for the hell of it, but for accuracy's sake wondering if there is a bearing and drive configuration would be cheap/light/strong for a lightweight bicycle. I'ts not important in any sense it's more a test of solidworks than engineering but I like to get things right.

Think something like this but less blatantly ridiculous.
http://www.welcometohr.com/wp-conten...ke-500x357.jpg

[bogan]

hmmmmmmmmm, one of the obvious challenges is to be able to get enough rigidity so it wont collapse under drive or cornering. So a wide angle between the bearings, and wide rims as well, probly 9 bearings per wheel, plus internal ring gear on the rear. Obviously wheels would be heavier than standard, but would look pretty cool!

[Ocean1]

There's no rules dude. Try a recirculating ball arangement direct on the rim, wrap a synchronous drive belt outside it.

It’s one of those “everyone tries it” ideas. Cute, but some perfunctory FEA work shows it’s not structurally a great solution. Spoked wheels and chains are still around for a damn good reason.

[Dare]

Obviously wheels would be heavier than standard, but would look pretty cool!

It’s one of those “everyone tries it” ideas. Cute, but some perfunctory FEA work shows it’s not structurally a great solution. Spoked wheels and chains are still around for a damn good reason.

That's pretty much the gist of it, there are only a few situations I see spokeless being a good option and this isn't one of them but as a styling exercise they are pretty fun to mess around with. Who knows, one day we might have materials or designs capable of coping with such craziness.

Thanks for the ideas

It has been done a few times but not with any great seriousness...
http://www.crunchgear.com/2010/02/16...eless-bicycle/
http://www.hyd-masti.com/2009/05/hub...e-without.html

[Dare]

Mua ha ha.

[Ocean1]

What's the assembly at 12 oclock on the front wheel?

[Dare]

Anti dive suspension ala bmw, needs to be a bit further back for leverage to work I think, cbf drawing springs in photoshop. The assembly is now over the wheel for extra tinyness.

[bogan]

so how does it hold the wheels on?

[Dare]

Like this http://www.youtube.com/watch?v=UHoHAmrEbrk

[bogan]

ah yip, so not hubless (for some reason i thought you were going for hubless), just a massive diamter hub. With a lot skinnier tyre used in bicyles you should get away with less weight as the single sider bit wont be so far offset.

[Urano]

i've been thinkin on that solution for a while.
it came to me with three main problems:
1- with that dimensions (and use) is pretty impossible to seal the bearing properly, so if you are going to use your bike outside a showplace you'll get stuck soon, after a pair of puddles....
2- as somebody sad, the wheel is going to be a ton heavy.
3- if you use the whole wheel width, you'll have pretty hard time to brake it. and disc brakes, like it or not, are still the most efficient.

so i'd turn to think that the best middle way could be a "diameter only wheel".
the fork connects to a rod which is in the diameter of the wheel. the wheel is a light alloy frame that rolls on balls put only where the diameter rod hit the circle. the diameter rod gives rigidity to the assembly and aside you can still put a disc, like buell...


now for a completely different thing. (can i borrow your thread? )
is there any engineer that is familiar with brayton?

[Dare]

Eeeeeef anyone is interested here is how it turned out. Slightly unfinished. Click le piccie for more uh, piccies.

[schrodingers cat]

Let me know when you build it. I'd be keen to pay to watch you jump it off something and learn what spokes actually do...

[bogan]

looking good dude, how much are those big mutha bearing gonna cost? also have you considered how the front pivot suspension would effect stability, methinks it'd get well twitchy under brakes.

[Dare]

Let me know when you build it. I'd be keen to pay to watch you jump it off something and learn what spokes actually do...

Nothing a big soft shock couldn't fix http://www.youtube.com/watch?v=wzLCgooA9KQ

looking good dude, how much are those big mutha bearing gonna cost? also have you considered how the front pivot suspension would effect stability, methinks it'd get well twitchy under brakes.

Probably not more than one of those 50g wheels on those fancy carbon road bikes. Yeah rake is directly affected by shock length/that bracket on-top of the wheel, is a bit exaggerated at the mo.