Tuesday, February 23, 2021

Live motorcycle Dynamics - Well, in a straight line anyway

 Someone on the MC Chassis list came up with this link.  The bike in the simulation is a one off being built by an individual using a Triumph 675 engine.  Not stated if he hopes to race it in Moto2, but it is a pure race bike.  It uses a SaxTrak front suspension which is a combination of telescopic struts with an A arm to the frame connecting just above the tire.

The simulation has a slider on the bottom that varies brake/drive and you can see the g's shown at the c.g.  I don't know how if the simulation is correct in all aspects, but it looks pretty right.  One thing that surprised me was how easily it was to take the vertical force of one tire or the other to zero.  That is, zero force on the front tire represents a wheelie and at the rear, rear wheel lift.


 https://ifold-estate.github.io/Saxon675Sim/

Wouldn't it be cool if you could change geometry, just to see what happened?  Of course, you can buy Tony Foale's software.  Anyway, something to play with and a good thought starter.

An update.  The page has been updated to allow change in rake and anti-dive, but how things work is a little unclear.  The green slider at the bottom may be braking, not engine drive, but the definition isn't clear.  It is also odd that both suspensions seem to be set up at near full rebound which explains why it wheelie's so easily.  I thought about withdrawing this post because it isn't clear what is happening, but then it is kind of fun to play with anyway.  Just season with the appropriate amount of salt.