What is the best gearing combination for my......
First and foremost, let me start off by stating there is no MAGIC gear ratio!
Look at all of the variables which can affect gearing:
- Rider: Physical size (weight and body type riders with more upper body mass (wide shoulders etc.) wheelie more than thinner built riders at the same weight), level of expertise, 'aggression level'. We typically remove a tooth (or two) for very aggressive types to curb initial wheel spin or wheelies in the top of 1st.
- Track: slick or sticky on the starting line, or finish line, bumpy down track (remove a tooth to slow wheel speed to increase traction).
- Weather: great conditions (bike can pull less gear and/or tends to wheelie more) poor conditions (needs more gear to get going), altitude, head wind, tailwind.
- Bike: power level, power adders, wheelbase, oil type, viscosity, foot-shift vs. button shift (rider may need more time for 1-2 if foot shifting) chassis (rake vs. offset clamps etc.) and suspension configuration, clutch adjustment, clutch type (lock-up vs. cushion), rev limiter (extended vs. stock), tire size, type (traction level), diameter, aftermarket wheel type (we remove 1 tooth for the addition of BST Carbon Fiber wheels alone), the list goes on forever.
- Theory: it's GREAT if your bike finishes the pass almost on the OEM limiter in the gear you decide is best for your application. Typically 4th gear for large displacement normally aspirated bikes (Busa/ZX-14 etc.) and 5th gear when using nitrous stock engine/wheelbase and mildly extended for riders less than 200 lbs. Up that by one gear for modified engines and larger riders. Most smaller displacement 1000 cc bikes are the same at stock wheelbase, but we have had our best results screaming the BMW's through the traps in 6th gear even with a stock engine and no Nitrous with small riders and 200 lb.- ers.
What is truly important is that your bike is rideable for YOU and that you are putting all of your power down as quickly and smoothly as possible.
YOU MUST lock the gas before the 1-2 shift, even if only for a split second, and shoot for the best 330 times attainable. Once you have this section of the track figured out, try to avoid shifting right before the lights as the added shift will add extra ET, kill momentum and drop your bike out of peak RPM's so your MPH will suffer. This is where having your ECU extended is a great advantage. You can sometimes add a tooth for the perfect front half, and then go through the traps without hitting the limiter.
The only way to get your gearing correct is to purchase a selection of sprockets and experiment. You might be able to get a fellow rider or bike owner with a similar combination to help you out, but even then with all of the variables involved ONLY YOU will be able to make the final decision on what is correct for your application.