Does ride have a short or a long vowel sound?

The Word RIDE contains a 'dipthong', which is a combination of two different vowels, in this case the long vowel 'aa' as in 'father' and the 'i' sound as in 'eat', such that the phonetic pronunciation could be written <raaid>. By nature, a dipthong IS a long vowel sound, because it constitutes not one, but two different vowels. Furthermore, since the dipthong in RIDE contains the long vowel 'aa' already, it must be "at least as long as a long vowel".