I often wonder about the same thing, seeing as how I'm biologically incapable of writing anything short.
My advice? Think carefully about the events that are going on in the "chapter". How does it start? What events are building up to the climax? What's the climax? What happens after it? How does the chapter conclude? Keeping a clear vision of what's supposed to go down in your chapter can help you decide if it's going to be really long (I suspect it's unavoidable, but others could disagree, and justifiably so) or if you need to splinter off one big chapter into multiple, smaller chapters.
Still, as long as your chapters are interesting, I don't see why there's any reason to worry about people getting bored/frustrated/annoyed by the length. Keep things exciting - with a dynamic, attention-grabbing beginning, though YMMV - and you could probably make them as long as you see fit.
Hope that helps you out.
edited 22nd Dec '10 9:11:20 PM by Voltech44
My Wattpad — A haven for delightful degeneracy@ Dae
I already had to split the story up. Not because of this, but because of Deviant Art's character limit for written submissions.
I general I'm mostly worried about the short attention span on the internet (when Too Long; Didn't Read is given an abreviation, we know we've got some problems.)
I wouldn't be too worried about a Too Long Didnt Read scenario. Those kinds of people aren't really interested in reading period.
That said, there's nothing wrong with 15,000 word chapters. I have 19 chapters in my work started so far with almost 63000 words total across 128 (soon to be 129) pages in MS Word, an average of 3300 words per chapter. A fair number of chapters are much shorter than that and a fair number are much longer than that.
So really, unless you can fit whole books of plot (and I mean whole books' worth) in that 15000 page chapter, there's no reason to worry about how long they should be.

So I'm writing a story in something of an episodic manner with each episode being a standalone story with elements that tie the entire thing together into an arc.
The problem is the length of each individual part. The first episode finally reached more than 15 000 words and the second one looks like it will do the same.
I'm worried that any reader is going t see the story, see a wall of text and then go: "I can't be bothered."
Should I cut my story into several, shorter, parts?