Hiya Robyn!
Welcome to planDisney!
Strollers in Walt Disney World Resort are an absolute must. Little legs struggle with all the walking and exploring of the Parks. Frankly, even this Mama's grown-up legs struggle. I use strollers in the Parks for my kids well past the age they have grown out of it everywhere else and I support and encourage every parent to get a stroller.
Keeping that in mind, there are rules about the strollers allowed in the Parks. While the smarTrike strollers do seem to fit the
sizing limitations of being no more than 31" wide and 52" in length they could be classified as bicycles.
Bicycles are only permitted in designated Disney Resort areas and not the Parks. I know that there is a "Stroller mode" which removes the pedals and puts in a foot stand but it still looks like a bicycle.
Disney Security is the final word when you arrive but there is a good chance it will not be allowed into the Parks. My suggestion is that you not bring that stroller and bring something more traditional that fits within the sizing limitations. Robyn, you may end up thanking me as a day in the Parks requires a stroller with a more reclining and relaxing feel as naps are a possibility. Long sunny days with so much excitement are sure to tire even the most strong-willed child. I know that my 9-year-old has wanted a chance to sit in the stroller for a bit during the long walk to the
complimentary bus transportation at the end of the day.
If you do take any bus transportation, remember that strollers must be folded up before boarding. Whatever stroller you bring make sure you practice folding and unfolding it while holding any bags you may be carrying. Strollers can be rolled right on the monorail and Disney Skyliner, though. Also, don't forget your cupholders! Where else will you store your
Tropical Serenade from Aloha Isle and your refillable water bottle? (No glass bottles of course) Make sure you make your stroller "pop" while in the Parks as it will be hanging out in stroller parking for some part of the day while you enjoy a nearby attraction. Locating your stroller in a sea of similarly colored strollers can be rough so I like to tie a colorful ribbon or even glow sticks to make it noticeable any time of day!
I hope this helps and if you have any more questions please feel free to let us know!
Happy Planning!
-Nimmy