canadian raising + non-final syllable

Okay, I apologize for asking about Canadian Raising again, but I just don't understand this and I was hoping you guys could make it any clearer for me.

After I discovered I have Canadian Raising I started looking for articles and stuff to read about it. At first I thought it happened only before voiceless consonants but then I read that it applies also at the end of a non-final syllable of a morpheme. I realize this is true cause I raise in words like "spider" as well and [d] isn't a voiceless consonant. The thing I don't understand is what on earth is a non-final syllable of a morpheme? Isn't the "ri" in "rider" a non-final syllable of a morpheme? So why doesn't it raise there too?

I hope you guys can help me out a bit with this!

Thanks in advance,

Lo.

I agree with what Josh said. And I would add that in my dialect (Eastern New England), Canadian Raising is strictly allophonic, with no morphemic influence at all. So I have:

rider ["r\aI4@`]
spider ["spaI4@`]

writer ["r\6I4@`]
spiter ["sp6I4@`]

I have Canadian Raising of the sort that not only "spider" has raising but also "idle" and "Idaho". Mine has morphemic influence, but from a strict standpoint Canadian Raising has been phonemicized in my dialect as their are certain words which one would expect to have Canadian Raising in my dialect but which lack it.

For the case of classical Canadian Raising I have:

rider [ˈʁaːe̯ɾʁ̩ː]
writer [ˈʁəe̯ɾ̥ʁ̩ː]
loud [ˈɰa̠o̯d̥]
lout [ˈɰɐo̯ʔ]

For the case of historical /aɪ̯/ or /aʊ̯/ followed by a consonant followed by /ər/ I have:

spider [ˈspəːe̯ɾʁ̩ː]
auger [ˈɐːo̯gʁ̩ː]

However, I have certain words which are monomorphemic and yet resist the aising of historical /aɪ̯/ followed by a consonant followed by /ər/:

fiber [ˈfaːe̯bʁ̩ː]
miser [ˈmaːe̯zʁ̩ː]
visor [ˈvaːe̯zʁ̩ː]

These words are why Canadian Raising is phonemic in my dialect.

I also have another class of words, of the form historical /aɪ̯/ followed by /d/ followed by a vowel (I cannot think of any cases with historical /aʊ̯/ at the moment):

idle [ˈəːe̯ɾɯː]
Idaho [ˈəːe̯ɾəːhoː]
Fido [ˈfəːe̯ɾoː]