Preparations for Bedford Heat

In the time since the Kent race back in June, Franc. N. Stein was on a strict weight loss and fitness plan. This included changes to the roll structure, rear suspension, chassis and rear subframe resulting in a weight loss of around 3kg - a worthwhile improvement. The wide rear wheels have been replaced with narrower tyres and hubs and the rear track reduced, saving further weight and reducing the all important rolling resistance. Thanks to William Slark and Family for sponsoring the new rims and to David Tingle of www.djtkarting.tk for the donation of his old race tyres. In years to come we may find that we’ve been running on the tyres of a Formula 1 world champion! The resin/spandex shell was replaced with a new skin incorporating a much tidier and more efficient front end. Our solar panels (which provide power for our motor cooling fans) were relocated from a rear wing to the top of the nose, saving further weight and drag. Other minor improvements included the addition of a cycle speedometer and a revised seat.

On the bench Franc covered 105km without any problems and showed good reliability in testing around the school playground, even a trip around the (not too smooth) school field did not show up any problems. The improvements in weight and rolling resistance were proved successful, solving the issue of our main fuse tripping under acceleration with our larger drives on board.

Why use those wheels?

A question we often get asked is why we are using kart racing slicks and hubs on Franc N. Stein. Originally the answer was "because we had them in the workshop" - Franc. N. was put together in little over 6 weeks prior to the 2007 Essex heat. However, apart from our spate of punctures in Kent we have grown to love our little wheels. They do have advantages - yes, their rolling resistance isn't as good as a well built cycle wheel and tire and their aerodynamic profile is poor (unless you compare them to a 20" disc in a cross wind), but, they are immensely strong, very cheap and their small diameter puts less strain on axle and steering components while gaining a lower centre of gravity. Rolling resistance isn't as poor as expected - the contact patch is actually quite small if the tyre is inflated to around 6 bar. We've tested them up to 8 bar but haven't run them at that pressure at a race yet. Their strength means we don't have to worry too much about cornering forces, at Kent we gained great advantage by being able to carry momentum through the notorious turn 3.

Build Pictures

The rear subframe running on the bench	Run in nicely after 105km
Looks fast!	Belt drive and motor cooling arrangement	New aluminium roll structure to replace heavier steel version
Braking system - disc has been skimmed and drilled to save weight. Caliper has been rebuilt with components drilled for weight saving.	The best tool known to man - the bead breaker for removing and replacing tyres. This saved days!	The sensor mount for cycle speedometer - a magnet is set into the main drive pulley.
Back together and nearly ready for a skin of Spandex