Originally Posted by YesImLDS
Top speed is always going to depend on gear ratio. You can out gear the bike though. I wouldn't recommend going very fast anyways there really isn't any point. I actually bought a bigger rear sprocket for my bike recently just due to the fact that there is no need for me to the top speed of the sprocket I had on there. Just dangerous and brings a bad name to motorized bicycle going ridiculously fast. That's why legislation is being passed now for our bicycles. 44T comes with the kit and that gets the job done. If you want a little bit more I recommend a 40T.
I completely agree with LDS here. You hit a 2" pothole (commom everywhere in Maine) @ 25mph you are gonna wreck your front wheel and get hurt. These are bicycles. Be wise and be safe first and foremost. If roads you travel are good I would not understand why you need to go faster than 25. Do you want to race? The streets are not for that. What do you use your bike for? Answer that question before you modify and get hurt on the street. I run a 44T on 4 diff bikes. 25 30 great. Good low end grunt which is most important in rural areas. If you can't keep with traffic keep right. No prob. Be fully reflectored use a front and rear light Day and Night. Be as legal and unobnoxious as you can. I have 2 bikes with 40T on the rear wheel. A little faster, not much but noticebly less Go from stop. Mind you all I do to my engines is lap cyl and head, No serious mods but it suits me fine. It is all about the application intended. I am a back and forth to work and occasional pleasure ride. If you want to race and do 40, 45 + You don't belong on the street with one of these. I want to apologize if I'm bold with my statements and offend but it really depends upon your personal application. Racing or from here to there transportation.
ALSO; Thanks to Tyler! All valid, excellent points.