What is a rally computer? Do I need one?

Before we even get into the explanation of what they are, no, you don't need one. If you had one, would you use it? Sure, just like if you had an awesome 28V cordless impact gun, you would use it to change tires, but you don't need one to go rally. Not these days.

So, what is a rally computer? It's nothing more than a fancy odometer. Like the odometer for your car, it has an overall mileage (generally reset at the start of the rally) and an interval mileage (think 'Trip Odometer') that is reset each time you get to each instruction on the transit. Pretty much, if you could reset the stock odo of the car to zero when you started the rally, and then you reached through the steering wheel at each instruction and hit the reset on the trip odo, that's what a rally computer does.

Why bother then? That doesn't sound too fancy? Ok, let's confess that we did say it was a 'fancy' odometer. The main fanciness is that you can calibrate it. So if you change to different size tires, or the temperature changes, or you're running on slippery snow, you could adjust the odometer so that it was still reading what the official mileage was.

All of this was much more important in the rally era of about 1985 to 2003-4. That's when the US got on board with stage notes and pace notes. Now, on stage the navigator is reading notes constantly. They match each and every corner up. And getting through the transits isn't that hard. Look at it this way: all the motorcycle guys make it there with stock odometers and no codrivers to help them! So transits aren't a problem.

They are neat and they're fun toys. Save the money for another entry fee though. And as far as "competitive advantage", there's plenty of stories of people these days winning rallies with rally odos that stopped working or were never even connected. So you aren't missing out.