It's this terrible drive angle that my calculator wasn't taking into account. It's this. The shaft also travels through a downward angle to the input drive - which itself normally goes through a 6° angle upwards, due to kick up.

Battery sag and tyre ballooning, whilst not technically calculated for, are mitigated by giving the user a range of inputs for each.

In my case I tend to test with belted tyres. Speed runs on unbelted tyres = disaster.

The only rig where my calculator was consistently giving 3mph over the real world results was the XTR.

Thus the new chassis layout.

Once I get some higher traction days, I can put all the theories to the test.

Despite a difficult first run, I can already feel how much punchier the rig is. This isn't just from the weight saving, but from more power getting to the wheels.