I wanted to purchase a couple sets of tires for the beginning of the race season so I called up Heidenau to order my K65Race compound tire sets. The rear I use is a 100/90-18. Well they were out of those so I ordered the 110/90-18 and hoped it wouldn’t make much difference. What I worried about was a slower turn in on the wider rear.
Took this tire set-up to Sandia Speedway for their first track day before race day to make sure everything was sorted. The error was that they ran what was called the Alt-Configuration. This very tight technical course had no long straights and the bike ran like a champ. Quick take off and I was able to use the whole tire so I thought all was well.
I found out that changing the tire size fromm a 100/90-18 to a 110/90-18 is the equivalent of increasing teeth in the rear sprocket. Race day was run in our regular configuration so there was now a much longer front and back straight. My starts were quick so I was running in front the only other bike racing in my class. I was amazed at how fast the rpms topped out in each gear and I found myself out of my regular shifting pattern running a whole gear ahead of what I usually find to be most efficient. I thought, “am I really going that much faster?”.
I was shifting up 3 or 4 gears on the straights and then had to shift down those gears going into the turns and I was counting in my helmet out loud to keep track of all this (while racing). I was making mistakes and could hear my competitors loud engine behind me. 1 lap to go and I would be first!! I came out of the the hairpin in 3rd gear (should have been in 2nd), rolled on the throttle and of course had no power at 6000 rpms. Just like that my lead was gone and I went from first to last. Tight ratios. I had to ponder what went on all the way home and thought my way through it. What I love about racing this bike is not my challenge as a physical rider but also the strategy involved get this bike to stay ahead on the track.