What is maximum gear ratio?

What is a gear ratio?

• Many people say i ride 42x16 or 51x50 or other things like that for fixed gear. im going to buying a fixed gear and i would like to know how i can figure out my gear ratio and how can i set it?

• Answer:

  Simply put a gear ratio refers to how many times a wheel rotates counter to the crank (pedal). Lets say for one crank the wheel turns 2.5 times. For someone learning ratios this is like greek 3:1, or 2:3 and so forth. This is the terminology expressed in answering your question. An easy way to remember gear ratios would be memorizing three sets. The first set, if a bike has a 39 tooth chain wheel and a 16 tooth cog in the rear this is an ideal gear for hills on a single speed. Pedaling is not to difficult, one can be off to a fast start. The problem with this gear is that you will spin out at 21-23 mph top speed. The most common gear is 42x16, this may very well be an optimal gear. Top speed will put you at 25 mph assuming you can pedal at 120 rpm, same for the previous ratio. If you have a 48x15 pedaling at 120 rpm you will be sitting at a windy 31 mph. Remember, the slowest top speed will be 39x16 however the rider benefits from fast starts, he gets up to speed in a few strokes and comfortably reaches a top speed 23 mph (Low gear) Middle speed is 42x16 which will yield slower starts but a better top end, hills are manageable (Middle gear) And then 48x15 will offer a very slow start in traffic, the rider has to bite down to get up to speed, but once you are up to speed you roll out at 31 mph (High gear). Its always a safe bet to start in the middle. Chances are you can live with the low gear, but you will soon want more speed, IF, you don't live in a hilly area or a mountainous region. If most of your ride is on fairly flat thorough fares the middle gear will suit you just fine. To better determine which gear is right for you, ask yourself about leg strength, is this a strong suit for you? If you are commuting low gear is ideal in traffic, leg strength can get you up to a cruising speed of 10-14 mph without much trouble in all weather conditions compared to the other gear sets, this is not bad at all in traffic, especially if you consider traffic is usually at a standstill. If you have open road, country road, any long non-stop roadways where you are riding into the village, city or town the middle gear is ideal. You can move at a nice clip with the assurance once you have started its down hill from there. Again wind will be a major factor in the fall and winter months. That very well may be why you hear so much about 42x16 gear set. If your purpose is to be a part of a bicycle club then high gear is best in keeping up with the Joneses. Hopefully this sorts out gear ratios for you. Enjoy. Best.