Why don’t MotoGP bikes have starters?


MotoGP bikes or motorcycles don’t have internal starter motors to reduce weight. This gives them the advantage of a higher power to weight ratio and is also good for when they need to brake since weight is a factor in momentum. To start the bike, they use a roller on the rear wheel or they need to push start it.

Overview

In this short article, we discuss why MotoGP motorcycles don’t have electric starters like normal production bikes. Also, why MotoGP riders always bump the bike when push starting after a crash.

We will discuss the following:

  • Why MotoGP bikes don’t have normal starters?
  • How are MotoGP bikes started?
  • Why do MotoGP riders bump the bike when push starting?

Why MotoGP bikes don’t have normal starters?

The main reason MotoGP bikes don’t have starters built onto or into the engines is that they add a lot of extra weight. Also, it makes it a bit more complicated to engineer, although that’s not so much of a problem.

Now I know that you’re thinking about how much a starter weighs and how you think it’s crazy to omit such a handy feature for a little bit of weight. So let’s assume that you use a starter from a Yamaha R1 which weighs around 5 pounds or 2.26 kg. Alright, but what about the extra casings on the engine and gears?

That might bring it up to 7 pounds if I have to take a wild guess. But are we forgetting something? Right… a battery! That’s probably another 8 pounds. But if you use a lithium-ion battery you are only adding about 1.5 pounds.

So, in the end, you have more or less 8.5 pounds or 3.85 kg of extra weight. It doesn’t seem like much but on a track, every bit counts. Seeing as a MotoGP bike would weigh only 350 pounds, another 8.5 pounds is actually quite a lot.

One thing that bothers me is that I couldn’t find anything saying that MotoGP bikes are not allowed to have starters or battries. Although, they stated that Moto3 bikes must have a battery.

Read the 2020 FIM GP World Championship Regulations

How are MotoGP bikes started?

MotoGP bikes are started using a roller starter (also called a paddock starter). There are many variants of these machines and some have a belt running over the rollers to get more traction on the tire.

The roller starter is simply placed underneath the rear wheel of the motorcycle or the motorcycle is pushed backwards onto the machine. The motorcycle is put into gear and the clutch is disengaged using the hand lever. Once the roller starter has started turning the rear wheel, the clutch is engaged to start the engine.

The other way to start a MotoGP bike is to push start it. You might have seen how the riders run next to their bikes and then jumping on before continuing with the race. They are actually trying to start the bike again. This is a bit harder to do when the engine is cold so a roller starter is used at the pits before the race.

Why do MotoGP riders bump the bike when push starting?

You might also have seen the riders stand up on the foot stands and then dropping themselves onto the seat when push starting after a crash. They do this to get more downward force at the exact time they leave the clutch lever to start the bike.

The simplified formula for friction is F=μN which we discussed in another article: Why are motorcycles’ front wheels narrower than the rear wheels?

The downward force is a factor in the equation for friction and would normally just be the force of gravity. But if the rider puts some momentum into his body and transfers it onto the motorcycle, it creates more downward force and also more friction.

Why is this important? MotoGP motorcycles are lightweight and the friction between the rear tire and the road might not be enough to keep the wheel turning when the rider releases the clutch lever. So creating more friction by bumping the bike helps keep the wheel from sliding when the clutch lever is released.

Final words

Unfortunately, I’m not an expert on MotoGP but I believe my answer is somewhat valid. I hope this article was helpful to you.

Featured image by Karl Saare.

I always try to keep my articles interesting and informative. And I’m always thankful when they are shared on social media platforms or Pinterest.

Two Motion

I don’t see myself as an expert in every topic of motorcycling but my articles usually relate to new experiences that are relevant at the time of writing.

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