First, an example of something you should never do.
Display the large version of the picture on the right by clicking on it, and look at the signs next to where this cyclist has parked their bike.
Can you see what's gone wrong here? Answer at the end of this post.
(The picture was taken on a Saturday market day at the north end of Broadway in north London, between Regent's Canal and London Fields. We can recommend the market for great food. But don't go there on an empty wallet.)
You can see a lot more bike pictures on my new Flickr site, which I'm adding to steadily. The 'Slideshow' on the left cycles through all those images; click on one to go to its full-size version on Flickr and to read details about the picture.
You'll see that my Flickr pseudonym is 'Dee Railer'. I spent ages trying to think of a bike-related name, but that's the best I could come up with.
But if you think that's bad, consider the rejects: Allen Key, Dinah Molights, Anna Tube, Ria Wheel, Kay Bultize... Unless, of course, you know worse.
Anyway, here's the answer to the picture question...
...ANSWER That's right - there's an apostrophe in 'Saturday's', which is clearly wrong, as this is a plural. Never do this.