Eeek! No Spokes!

Ian Smith said:

Chris Eilbeck said:

Ian Smith said:

I think that you're forgetting that bicycles lean in a turn (or at
least, your description does not address it).

How do you folk with fixies avoid the pedal hitting the ground on the
inside of a turn?

Well personally, I ride a trike.

And they are not easy on spokes judging by mine after a few thou.

Chris Eilbeck said:

Ian Smith said:

I think that you're forgetting that bicycles lean in a turn (or at
least, your description does not address it).

How do you folk with fixies avoid the pedal hitting the ground on the
inside of a turn?

Go slower and/or use shorter cranks.

Tim

dkahn400 said:

The Luggage said:

When going in a straight line, all the forces act in the plane of the
rim, so can be transmitted relatively easily round the rim from the
ground to the 'hub'. When you turn a corner, there are suddenly lots of
forces trying to bend the wheel.

No there aren't. The lean when cornering keeps the net force acting
mainly in the same plane.

Yebbut...

This is only true when travelling at moderate speeds. Whenever the
front wheel is no aligned with the frame (ie the bars are turned) there
will be lateral forces on the wheel. When moving at speed, the bars
basically don't turn at all, but they certainly do at lower speeds.

TL

"Tim Hall" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Chris Eilbeck said:

Ian Smith said:

I think that you're forgetting that bicycles lean in a turn (or at
least, your description does not address it).

How do you folk with fixies avoid the pedal hitting the ground on the
inside of a turn?

Go slower and/or use shorter cranks.

Or bigger wheels.

"PhilD" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Ian Smith said:

I don't think it's practical with current
materials technology, though might be theoretically viable if you grow
your rim as a single seamless crystal of something very stiff (hence
my reference to diamond).

Or alternatively, stiffen and strengthen the rim with something like,
um, spokes!

Oh, hang on a mo...

PhilD

It's not a hubless bike, anyway, each wheelset has three hubs....

Simon Brooke said:

in message <[email hidden]>, Simon L

(') said:

Quoted message said:

I don't think gyroscopic effect has much to do with it - it's more
about steering geometry and weight distribution.

Shirley rotational momentum in a plane - the gyroscopic effect - is all
there is to it. My bike is hideously unstable when it's not moving.

We've done this before; I'm not going to rehearse it all. If you want to
look it up, the thread is entitled 'The Stability of the Bicycle' on
news:rec.bicycles.tech in October 2003. I still have the movies I made of
my various experiments in the course of that discussion, and can post them
back on the web somewhere if anyone is interested.

In summarry, the gyroscopic effect has very little impact on the stability
of a bicycle - it's there, but it isn't sufficient to make any difference
at any normal speed. Bicycles remain upright while moving because the
rider steers to the side they're leaning towards, bringing their wheels
back under their centre of gravity. With suitable steering geometry this
can even be semi-automatic.

David Jones published an article in the April 1970 edition of _Physics
Today_ which demonstrated this pretty conclusively. It's on the web
somewhere... rummage... rummage... Here:
http://ist-socrates.berkeley.edu/~fajans/Teaching/MoreBikeFiles/JonesBikeBW.pdf

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

Dear Simon,

An email informs me that the movie is hard to find.

I've warned you before about not rehearsing it all enough.

Hitchcock was right--actors should be treated like cattle.

If you think that I'm going to split the popcorn proceeds with you,
think again!

Here's the director's 12 mb cut of full frontal Simon Brooke and
bicycle. It includes the controversial scene with the handlebars
removed before the wheel-slapping begins. Not for younger audiences.
Rated TG for tilt-and-gyro.

http://www.youtube.com/v/GyKTpKTJoAg

Youtube downloads much faster than filelodge.

Cheers,

Carl Fogel, Medulla-Oblongata-Glutz, Ltd.