Wheel speed sensors 5-10% out front and rear?

[Monners]

I've been looking at my data after the weekend. I've been looking at traction control as I very rarely have it on anything but the minimum because I dont like the intervention but this time ran it on -3. The rear wheel speed matches the GPS speed so that looks ok but the front is always 5-10% lower and I'm thinking it explains why it seems to intervene too much. I'm fairly sure it's an error in the readings rather than any actual slip. I recently replaced the speed sensor at the front with a second hand one and wondered if anyone has had a similar problem; perhaps a gen 2 speed sensor is different or something and I've accidentally got one of those?? Unfortunately I dont have any data from before this.

 

[alex]

Will check mine when at office.
But is it not down to the 2 wheel sizes being different?


- Alex

 

[alex]

Here. You can see the differences on mine.

 

[scooby]

David,just looked at my data (sorry been a bit busy ; ).there are quite a few times front is well under rear speed,but they can be explained though,usually on fast,throttle on corners (sito pons for example@jerez) my front is 12mph less,but thats a part of the track the rear spins up,plus coming out front has some lift.
saying that,max difference is no more than 11%

1,when on a straight are they same?
2,have you overlayed traction or anti wheelie spikes to see if it's front lift
3,is it on any particular corner type?

as for the sensor,it wont make any difference as it's a basic hall sensor so only time a variation will matter is if sensor ring is wrong or damaged.

 

[DrIoannis]

Since the diameter of the tyre is different when leaned the speed will also be different depending the lean angle. I do not know if you have RCK but if you do this is what you correct in the SlipCorection map. Also keep in mind that in acceleration the rear has more slip and the front end might be lighter and the front tyre just barely touch the ground and register lower speed.

 

[Monners]

Thanks for the comments guys. I did try to upload some data earlier but got distracted by less important work stuff I'll get them uploaded later.

 

[Monners]

Here we go; some very different situations to show the consistent slip of 15-20%. One is an extremely cold Cadwell last weekend with TC -4 which was very intrusive and the other is Jerez in sunny grippy conditions with the lowest -7 TC and Michael Laverty riding. I must emphasise that the bike feels fast and no major issues when rising; I'm just trying to optimise things using the data and these readings dont seem right?

The green line is rear wheel velocity and the orange is front wheel velocity. In the bottom graph you can see the grey line showing TC torque intervention.