Gear Ratio Map – Visualising The Best Gear For Any Corner

Working out the best gear ratio map to take a corner is not always straight forward. You know being in the “right” gear will help you gain the greatest acceleration. You also know that the extra speed will result in you doing quicker lap times. However, knowing the best gear to be in is not always clear – particularly with mid-range gears.

“Is that a 3rd or 4th gear corner?”

Said every racing driver, EVER!!!

There is a danger if you take a gear that is too low, that you will either:

• over-rev the engine, or
• over-slow the car

At best you will lose lap time. At worse you will damage your engine.

Run a corner in a gear that is too high however and you will:

• miss out on engine braking on the way in, and
• have slow acceleration on the way out.

Again, at best losing lap time. At worse running out of track…

If you have seen some of my other articles on gearing, then you will know that you can calculate the answer ?

With some basic data, you can work out what the “right” gear should be for any speed in your individual racecar. If you are not familiar with how, then see the box below:

So you have your gearing ratios optimised and you know your best shift points. You should have a table that will look similar to this:

The thing is, you likely visit lots of different tracks.

What would be great is if you could use your calculations to work out the best gear to be in anywhere around these tracks.

The advance spreadsheet will show you but it does involve some manual input. You need to transcribe your velocity curve into the sheet. It is ok but slow to do during a track session, ironically when the information could be most valuable.

See The Best Gear Ratio Mapped – Automagically

What would be even better, is if you could somehow use your logged data to automatically show you the best gear choice around the track.

A clear, simple visualisation of the ideal gear to be in at any point around the track.

Furthermore, it would be also super useful somehow use this information to assess how well you were doing at selecting the ideal gears.

Imagine if you could SEE anywhere that you had opportunities to improve …

Introducing The Gear Ratio Map

This is an actual gear ratio map:

It is a track map (Cadwell Park in the UK) but colour coded to show you what gear the driver was in anywhere round the lap.

This is one lap showing the drivers fastest lap. Hopefully, you can see that where I mouse over the different parts of the track it shows you what gear the driver was in.

This is an ideal gear ratio map:

Again it is a coloured track map. This time is it showing you the ideal gear you should choose based on your gearing calculations (see links above!)

You can then do a spot the difference and work out where you can improve.

To make that a bit easier, I have created this third view – the Gear Ratio Opportunities Map:

This is the actual gear chosen minus the ideal gear suggestion.

Anywhere there is a colour difference (being pointed at), the driver might enjoy being in another gear. In this example, it shows places where a gear lower might be faster than what he chose.

Pragmatism Always With Data

I say might on purpose. This is because the theory considers the car on a pure speed basis. It does not consider the environment the race car is in – the corners, gradients, time to change gear etc.

What the theory suggests is that if you had an instant, effortless and seamless shifting gear box then you will be fastest in the ideal gears at these points around the track.

You need to interpret this recommendation accordingly. The great thing is the ideal gear ratio map gives you certainty on what the best gear should be. It also highlights precisely where your driver is not following the theory so you can improve.

You can then work out how practical it is (or not!) to get the driver to change what they are doing to go faster.

Use The Data To Reduce Your Uncertainty

The aim, as always with using data, is to use data to help reduce your uncertainty.

If you are unsure whether a corner is 3rd or 4th gear, you can use this method to get a precise answer. You can then decide to adopt the recommendation (knowing it is fastest) or consciously decide to take another path (due to the track design or whatever).

Either way you are on the front foot. You will know, for sure, which is the best gear to chose. You can also then see how well you (or your driver) is able to achieve that plan.

Gear Ratio Maps In 3 Steps Using AIM Race Studio

You can create these maps with any GPS data analysis system that allows you to:

• colour code the track map trace with logged data, and
• allows you to create Math channels.

To show the gear that the driver is actually using, you also need to have this enabled in your data logger. Often the selected gear is calculated by the logger from Speed and Revs – so you will need RPM logged.

If you do not have drivers selected gear logged you can sometimes guess it by looking for dips in the longitudinal acceleration trace.

Either way you should still be able to create the ideal gear ratio map as long as you have the GPS speed trace that most loggers / GPS lap timers have.

If you happen to run an AIM device and would like to try to replicate these maps, then here is my 3-step process:

1 – Derive the speeds for your ideal shift points.

Using your own calculations, or one of my spreadsheets, you need to create a table like this one:

It shows you for any speed, what is the best gear to be in. In case you have not done this before, there is only one best gear for any racecar speed. Plug in your data (per my articles above) and you can work this out.

2- Create an “Ideal Gear Channel” in AIM Studio

From within AIM Studio, click on Modify -> Math Channels.

Then create a new Math channel. Here is my equation if you want to just copy it in:

IF(LT(GPS_Speed,28.1),1,IF(LT(GPS_Speed,52),2,IF(LT(GPS_Speed,74.8),3,4)))

You now just need to replace the numbers in bold with your speed numbers for your optimum shift points.

For example: If your 1st to 2nd speed was 35mph. Replace the 28.1 with 35.

“Nested If Statement” Explained

I’m using a simple “nested if statement.”

In case you are not familiar with an IF statement they are very useful and quite simple.

The equation first checks whether some check is true or false. If it is true it does one thing. If it is false it does another.

Think: If this then do that, otherwise do something else.

So in my example, it first checks whether the racecar is travelling at less than 28.1mph. That is what the “LT” is in the equation – Less Than.

It does this by looking at the Speed trace data – a channel called “GPS_Speed” you will see in the equation.

From Table 1 above, you will see that 28.1mph is the speed when the driver in that racecar should be changing from 1st gear to 2nd gear.

If the racecar is going slower than 28.1mph then the equation returns the number 1 – for 1st Gear.

If the racecar is going faster than 28.1mph then the equation moves on to the next if statement (Else is indicated with the final ” , ” above.)

This next If statement checks to see if the racecar is going less than 52 mph. As 52mph is the speed to change from 2nd gear to 3rd gear. Remember, the speed must be more than 28.1 mph because it past the first If statement check.

If the speed is below 52mph then it returns a 2 – as the best gear should be 2nd.

If the speed is above 52mph, then the equation goes to the next if statement.

74.8mph is the speed to be changing between 3rd and 4th gear. If the speed is less than 74.8mph the equation will recommend 3rd gear.

This car only has 4 gears. If the speed is above 74.8mph then the equation will then recommend 4th gear.

If you are doing this and your racecar has more gears then you can add another if statement instead of the 4.

3- Visualise The Ideal Gear On The GPS Map (or Measures Chart)

Once you have created the ideal gear channel you can visualise it in a few ways. You can plot it in the GPS map like above and/or the measures chart like this:

Here you can see the the speed trace at the top, the actual gear selected by the driver, and the ideal gear he should be in.

Again spot the difference. You can see lots of areas where the driver might have chances to improve. Remember there is the selected gear and the timing of when they are changing gear. Two performance aspects that will improve lap time if achieved.

I’ll now take you through that corner by corner so you can get a better idea of how to interpret this information.

Worked Example: Gear Ratio Map In Action

This driver has done pretty well. There are only a few places where he should choose a difference gear. I will take you through each of the suggested areas to improve. Then summarise with the one or two main suggestions that will enable the driver to go faster.

I will also use the Gear Ratio Opportunities map (below) to make this a bit easier.

Remember this map shows the gear ratio the driver used minus the ideal gear ratio for the cars speed.

If you are not familiar with Cadwell park, it is a clockwise circuit. The start/finish line is here:

Working round the lap, the first big opportunity is the right hand corner coming on to the straight. See the cross for where I am talking about:

This is a clear opportunity. The topology of this track is hilly though. A gear change here would potentially unsettle the racecar. It looks like there is more opportunity to instead try to carry more speed through that corner and stay in 4th. One to consider but potentially hard to do and risky.

The next area is again because of a corner. The driver is short-shifting on purpose here to settle the car before the corner. The ideal change is near the exit of the corner so could be difficult for the driver to action. There is a risk of missing the change and losing more time so the driver is doing the right thing. It would be worth asking the driver if they could hold 3rd for slightly longer but the current approach is understandable.

The next corner again drops away on exit. It looks like the driver can carry more speed through here and should focus on that rather than the down change. If not then there is speed to be gained if they can get the down change done without unsettling the car.

For this slow left-hander, the suggestion is for 2nd. Again the upshift would come very quickly. With a seamless box, it would be worth doing. For this driver in this car, not one to try to act on.

Along this short straight, the driver is changing up too early. They should focus on using all the revs and changing at the recommended RPM. An easy win.

In this next left-right, it goes quickly uphill. A clear area for a gain here. The driver should definitely do this in 2nd. Another easy win.

Here the driver is briefly up shifting to 4th. Another easy win here would be to stay in 3rd. Less gear changing and less likelihood of unsettling the car.

During the hairpin right, the driver is doing this perfectly. Both in terms of the gear selection and the timing of the change. I thought it worth highlighting this – we can get bogged down in the negative too often and this is great gear changing.

Next, the ideal is suggesting a quick down change and then back up again. It is too brief, however. The driver would do better to keep it in 3rd as he is doing. Ideally, he would carry a bit more speed on entry here.

Finally, the driver would be faster if he held it in 3rd gear a little longer. Another easy win.

In Summary

Hopefully you can see that this method of creating a Gear Ratio Map can be very useful?

It is useful both in terms of determining the ideal gear to be in at any point on the track. And, if you have the drivers selected gears, to improve on the timing of gear selection you actually do.

I’ve used AIM Race Studio as the example analysis program. If your analysis program does not allow you to program Maths channels then remember you can try my spreadsheet instead.

Best of luck and let me know how you get on putting this into action!