Jettsons factory HRC CRF250R video.. what is that?

Johnny Depp wrote:

ABS aka Traction control

Johnny Depp wrote:

ABS aka Traction control

Sawfish wrote:

Sometimes I wonder why you even bother posting.

SEEMEFIRST wrote:

Or more commonly known as a proximity switch?

mxtech1 wrote:

Those sensors are called hall effect speed sensors. As you can see in the picture, the speed sensor is bolted to a special bracket that is...

Those sensors are called hall effect speed sensors. As you can see in the picture, the speed sensor is bolted to a special bracket that is custom machined into the inner wheel spacer. The cable running up the swingarm is a 3-wire setup (12v, Ground, Signal) that terminates back at the data logging device.

HRC machines the hub with a specific pattern. Each square is the same size and the pattern is arrayed about the hub axis at a known diameter. These dimensions are important and used in the post-processing of the signal to calculate wheel RPM.

These types of hall effect sensors are mounted so that they have a small air gap (typically <1mm) between the sensing surface (the ring in the hub with the gap array) and the surface of the probe. Using 12v input power from the bike battery, the sensor measures changes in magnetic field. So every time one of the square gaps passes across the probe, the magnetic field is lost. When the wheel rotates through the air gap and the sensor is now reflecting into the solid metallic material in the ring, the magnetic field is returned.

The output of the sensor is usually a mode, either 1 or 0 (which can also be interpreted as magnetic field on or off.) In terms of a data output, we end up with a signal that looks like this as the wheel rotates through the gaps.




The "signal" coming off of the speed sensor is then fed back to the data logging device where it is stored. Keep in mind this is all happening at a very high fidelity rate....probably >100hz (100 data points per second) When the technicians upload the data, it is processed in a special software that can calculate wheel speed (RPM) given the amount of time between the mode changes in the signal and the array dimensions from the hub ring.

Why is wheel rear wheel RPM important you ask? Good question....

Simply put, it is probably the single most important piece of data to understand how much forward traction the bike is getting. It validates the accuracy of the software profile mapped onto the ECU. You see, there has to be a downstream component that is providing feedback to the modeling to understand if it is accurate or inaccurate. In this case, the model is the "map" that the engine technician has put into the ECU. Since the rear wheel is fixed to the crank via mechanical connections with known ratios, it is easy to compare expected wheel speed vs. actual wheel speed.

Where it gets interesting, is that they are also logging data for TPS voltage, ignition (timing), fuel delivery, and CPS or TPS. With all of these inputs, they can model how fast the rear wheel SHOULD be turning given the amount of throttle opening and how quickly the throttle is opened. If the rear wheel RPM is significantly faster than the model's calculation, than it will be interpreted as loss of traction and the rider is not utilizing maximum potential forward traction. There would be a certain target % of slip they are trying to achieve to always carry forward traction. If the rear wheel RPM is constantly higher than the models prediction, they would go into the mapping and make some adjustments such as retarding the timing to mellow out the power delivery. If the rear wheel isn't slipping enough, the bike could be tight feeling and they would go in and add-in some timing and fuel to get more power to the rear wheel to help break it free. Just depends on the track conditions and rider preference, but make no jokes about it, it is an incredible tool and tuning capability that only only the Factory teams understand how to use. Once the signal is translated to RPM, they can then plot RPM vs. time to establish a trendline, which would be useful to overlay against expected RPM to look for big deltas. Since most riders are wearing something like an Apple watch during motos, they can overlay the GPX data vs. rear wheel RPM to find certain sections of the track where the rear wheel is spinning too much resulting in the rider losing time due to not enough forward traction. This could be important in motocross for long straightaway speed and/or tracks with traction-limited surfaces.


If you are a traction control conspiracy theorist, keep reading..... the rear wheel speed sensor signal feeds into the ECU to provide a feedback loop to validate the ECU map in live time. Everything is there.....all it takes is that 1 extra wire and a software routine programmed on the ECU RAM to use the instantaneous rear wheel RPM data to compare against the predicted rear wheel RPM given all the same inputs mentioned above. All this looping can be done in milliseconds as the rider is twisting the throttle. I'm not saying this is occurring, but I am suggesting that all of the pieces are there, the theory is proven in other disciplines, and it would be hard to detect unless you had access to the data logger AND the ECU architecture (insert LOL @ AMA Tech here)

FGR01 wrote:

You guys notice many new stock bikes have traction control switches right on the handlebar?

MyBobbym wrote:

Traction control without an automatic trans of some sort would be ridiculous.

MyBobbym wrote:

Traction control without an automatic trans of some sort would be ridiculous.

FGR01 wrote:

You guys notice many new stock bikes have traction control switches right on the handlebar?

mxtech1 wrote:

Close, but not quite the same thing. While the rider can use a button to change between maps, or engage launch control, nothing within the ECU...

Close, but not quite the same thing.

While the rider can use a button to change between maps, or engage launch control, nothing within the ECU parameters are changing once that mode is selected. So that’s what we call a static or dead setting, meaning it cannot dynamically change during operator use.

Factory ECUs may very well be running “live” schemes where the TC loop is constantly self-evaluating (at every throttle position and in all gears) and adjusting itself to maintain certain performance targets set by the tuner.

MyBobbym wrote:

Traction control without an automatic trans of some sort would be ridiculous.

slowgti wrote:

Without a wheel sensor to use a slip ratio percentage, it’s more of an engine speed rate of change limiter. It’s basic TC, but with enough...

Without a wheel sensor to use a slip ratio percentage, it’s more of an engine speed rate of change limiter. It’s basic TC, but with enough testing it can be effective. There are some series that don’t allow the use of wheel speed sensors, the good teams are using some pretty fancy math to achieve basic TC. Think formula drift

mxtech1 wrote:

Those sensors are called hall effect speed sensors. As you can see in the picture, the speed sensor is bolted to a special bracket that is...

Those sensors are called hall effect speed sensors. As you can see in the picture, the speed sensor is bolted to a special bracket that is custom machined into the inner wheel spacer. The cable running up the swingarm is a 3-wire setup (12v, Ground, Signal) that terminates back at the data logging device.

HRC machines the hub with a specific pattern. Each square is the same size and the pattern is arrayed about the hub axis at a known diameter. These dimensions are important and used in the post-processing of the signal to calculate wheel RPM.

These types of hall effect sensors are mounted so that they have a small air gap (typically <1mm) between the sensing surface (the ring in the hub with the gap array) and the surface of the probe. Using 12v input power from the bike battery, the sensor measures changes in magnetic field. So every time one of the square gaps passes across the probe, the magnetic field is lost. When the wheel rotates through the air gap and the sensor is now reflecting into the solid metallic material in the ring, the magnetic field is returned.

The output of the sensor is usually a mode, either 1 or 0 (which can also be interpreted as magnetic field on or off.) In terms of a data output, we end up with a signal that looks like this as the wheel rotates through the gaps.




The "signal" coming off of the speed sensor is then fed back to the data logging device where it is stored. Keep in mind this is all happening at a very high fidelity rate....probably >100hz (100 data points per second) When the technicians upload the data, it is processed in a special software that can calculate wheel speed (RPM) given the amount of time between the mode changes in the signal and the array dimensions from the hub ring.

Why is wheel rear wheel RPM important you ask? Good question....

Simply put, it is probably the single most important piece of data to understand how much forward traction the bike is getting. It validates the accuracy of the software profile mapped onto the ECU. You see, there has to be a downstream component that is providing feedback to the modeling to understand if it is accurate or inaccurate. In this case, the model is the "map" that the engine technician has put into the ECU. Since the rear wheel is fixed to the crank via mechanical connections with known ratios, it is easy to compare expected wheel speed vs. actual wheel speed.

Where it gets interesting, is that they are also logging data for TPS voltage, ignition (timing), fuel delivery, and CPS or TPS. With all of these inputs, they can model how fast the rear wheel SHOULD be turning given the amount of throttle opening and how quickly the throttle is opened. If the rear wheel RPM is significantly faster than the model's calculation, than it will be interpreted as loss of traction and the rider is not utilizing maximum potential forward traction. There would be a certain target % of slip they are trying to achieve to always carry forward traction. If the rear wheel RPM is constantly higher than the models prediction, they would go into the mapping and make some adjustments such as retarding the timing to mellow out the power delivery. If the rear wheel isn't slipping enough, the bike could be tight feeling and they would go in and add-in some timing and fuel to get more power to the rear wheel to help break it free. Just depends on the track conditions and rider preference, but make no jokes about it, it is an incredible tool and tuning capability that only only the Factory teams understand how to use. Once the signal is translated to RPM, they can then plot RPM vs. time to establish a trendline, which would be useful to overlay against expected RPM to look for big deltas. Since most riders are wearing something like an Apple watch during motos, they can overlay the GPX data vs. rear wheel RPM to find certain sections of the track where the rear wheel is spinning too much resulting in the rider losing time due to not enough forward traction. This could be important in motocross for long straightaway speed and/or tracks with traction-limited surfaces.


If you are a traction control conspiracy theorist, keep reading..... the rear wheel speed sensor signal feeds into the ECU to provide a feedback loop to validate the ECU map in live time. Everything is there.....all it takes is that 1 extra wire and a software routine programmed on the ECU RAM to use the instantaneous rear wheel RPM data to compare against the predicted rear wheel RPM given all the same inputs mentioned above. All this looping can be done in milliseconds as the rider is twisting the throttle. I'm not saying this is occurring, but I am suggesting that all of the pieces are there, the theory is proven in other disciplines, and it would be hard to detect unless you had access to the data logger AND the ECU architecture (insert LOL @ AMA Tech here)

SEEMEFIRST wrote:

Or more commonly known as a proximity switch?