You could practice DUI defense for an entire career, and never get a "biking under the influence" case, or a golf cart case, or even a case of riding a horse under the influence. But if you do, the definition of what constitutes a vehicle, versus a motor vehicle will be vitally important in your analysis.
Vehicles are defined under C.R.S. section 42-1-102(112). But you also need to follow-up with C.R.S. section 42-4-1301, which also focuses on "vehicles," as opposed to C.R.S. section 42-4-1301.1, which concerns "motor vehicles." These differences can play significant roles in both DMV issues and trial court suppression issues.
For example, when you apply for a driver's license, you do not express your consent to possible future chemical testing if you are later found to be operating "any vehicle." You only give your express consent to any future chemical testing if you are found to be operating a "motor vehicle." Therefore, your case may have very different DMV and constitutional law issues, which must be separately analyzed.