Tuesday, 15 May 2012

Wheel Spats Part II

Having lowered the front wheels and replaced all the suspension springs with nylon spacers, I trimmed the spats to give 10mm ground clearance. This may prove to be insufficient even for testing at Reading Velodrome, but I thought it was a good starting point.
Underside of Quattro
Wheel Spats Trimmed
Once the spats were trimmed, I turned Quattro over to check the tracking. It was way out. The front was very toe in and the rear was slightly toe out. This would suggest that my new Ackermann compensating rods are not doing a very good job at controlling bump steer. Hopefully this will not be a problem for the spat tests, now that the suspension is locked out.
Foam Strip
I used some adhesive foam strip to locate the spats before I taped them in place.

Ground Clearance
All four spats are taped into position and have very little ground clearance.
Spatted Beano
Testing at Reading Velodrome was a bit tricky as the weather conditions were very blustery. Steve quickly got going in the newly spatted Beano before the rain started. He managed ten or so laps at about 38mph (60kph) but was having trouble with the wind and stopped when the rain came down.
I got going just as it started raining and was being blown about quite badly by the gusts. The spats were hitting the ground on a few of the bumps and the handling seemed horrible. I did about 20 laps, including three roll down tests from 28mph to a stop which took more or less two laps (950m). Graham Sparey-Taylor asked me to try and gather some data from my Garmin that he could analyze to verify the rolling and air resistance of my Quattro. We then took the spats off Quattro and I taped up the wheel cut-outs to reduce the gaps. I then repeated the 20 laps with roll downs.
The conditions were not good enough to draw any real conclusions from the testing we did. My gut feeling was that the spats made me a little faster. Also, I was expecting the handling to be better without them but in fact it was still horrible. So I will give them a try at the next race. Steve didn’t like them and felt they didn’t help his speed and will race without them. The banking at Reading is also a bit flat for Beano speeds and he was grounding the spats on the bends. Our next race is at Quibell Park Stadium, which is a large outdoor velodrome with a good smooth surface and steeper banking than Reading.

1 comment:

  1. Reading your fascinating blog-- one comes to the realisation that maybe the limits of aerodynamic development are being reached? I'm just counting the days until I get my Quest XS so I can quantify the performance gains (if any) in hilly terrain over my current steed. (Grasshopper fx with Rohloff) I'm expecting a weight increase of about 7-8 kg which means some of the hill climbs will be hard work!