Help! Larger profile tire or wheel?
It seems to me that after the initial rave of electric scooters died down in 2009-2010, this forum largely became inactive.
Nevertheless I hope to get some positive response;
I bought an X-treme XB-700Li, with LiPo4 battery. It's limited to 20MPH; but I live in Florida, where the law still allows these bikes to go upto 30MPH. I know many have commented that their bikes in reality do not surpass the 18MPH, so I wanted to know if I can equip my bike with a larger profile tire?
Here in Florida everything is basically flat, and few roads have sub 30MPH speeds. I have less use for torq, and realize if I can extend the wheel (make it larger),or put on a larger profile tire, I might be able to exchange some of that torq for speed and increased mileage per charge.
The only problem is, which wheel can I exchange it to, or which tire is best?
So you believe me now that the 700li only goes 20mph? :) Your newer LIfePO4 batteries should last longer than my LiMn. What is your range on a charge? I swapped out the original tires for the Chen tires which fit the 13" rim, and they were definitely a little larger. Did I get more speed? No. According to my bicycle speedomter, I was still topping out around 19mph on level ground. I don't believe that 700 watt motor and 48 v system had the torque to push it beyond that. Just my 2 cents.
I've got the XB600, which is about the same for power. I know what you mean about feeling limited in speed on the flats. My understanding is that the controller is rev-limited, and will reduce power as the rev limit approaches. With a high-grade calibrated bicycle speedo, I've found that that limit is almost precisely 20 MPH.
I would carefully measure the bead diameter of your present tires and have a "quality time" talk with the tire salesman to make sure you get the right size. The nominal size matters too, so don't neglect that.
I don't believe that the overall diameter would ever be more than a few percentage points greater that the stock tires, so the effect of top speed would be correspondingly minor. The most effective way I know to feel better about your speed is to give the scoot to a friend and try to keep up this him or her on a bike.
That said, I suspect that you will see better cornering and reduced rolling resistance from higher grade tires. You are running them at maximum pressure?
The Cheng Chen tires I put on my 700li were definitely larger. And I did recalibrate the bicycle speedometer for the larger diameter. I didn't get any higher top speed, as it still maxed out at almost exactly 20mph. I believe the factory speedometer read a little lower due to the larger front, which would make sense. It did ride much much nicer with the larger tires. I am 6'2" 225, so yours will do a little better. I was impressed with how well the 700li was able to climb hills. Anyone who says 27mph is either selling them, or has added extra cells to their battery pack.
The meaning of larger tires is to put them on the rear wheel, where they would have effect, not on the front!
Correct. I replaced both front and rear with the new larger tires. I actually did the rear one first and tested it for a couple hundred miles, and then replaced the front one later and recalibrated the speedo accordingly. My top speed was unchanged. But the improvement in ride quality was remarkable.
And just to give you another example, I actually replaced the rear tire on my 4000li with one that is considerably larger. The new tire is 2 inches taller in diameter. My top speed remains unchanged at around 55mph, but my accelaration from a dead stop is definitely a little slower, and of course my hub motor is turning less RPMs at higher speeds. But the higher gearing via larger rear tire didn't help there either, and my range actually suffered a little. But again, the ride is very nice on the larger tire.
What you say is impossible, as the controller inside the bike does not know how fast you are driving (relative to your environment).
If the motor happens to be of the brushless type, then of course the controller knows precisely at which RPM the motor is running, and if it is not slipping on ice or sand, the vehicle speed could easily be deducted by the controller.
Nevertheless, a larger tire on the driven wheel will only lead to higher max speed if there still is enough surplus torque in oder reach the same speed as before, but at lower motor RPM, AND even more surplus torque in order to overcome higher aerodynamic and/or friction forces due to the higher speed.