Math and numbers rule! You can learn a lot from them.
This weekend I put my nose to the grindstone and measured the weights for my bike and weight distribution.
Bike weight (full of fuel) – 444.5 lbs.
Ride weight (no gear) – 203 lbs.
Gear weight – 18 lbs.
Weight distribution – 49F/51R
(note : weight shifts rearward as bike consumes fuel.)
This sucks. A bike should have an equal weight distribution or a slight bias to the front. I’ve got the opposite situation.
Initally, I was testing this bike with the final drive gearing at 15/48/118. That produced a wheel position that was almost exactly in the center of the slot. That was really great given not knowing the weights of the bike. It gave some range of gearing either way and was the perfect place to start. Then, after a few rides, I decided that the gearing needed some adjusting and went to 15/50/118. This is perfect for now and will probably be perfect when the Yoshimura gearbox goes in. The problem here is that the wheel needed to be moved to the front of the slot. Fun if you like lifting the front wheel but not great for traction.
Given the measure of 1410mm wheelbase and that the CoG works out to be 720mm behind the front wheel, the rear wheel needs to move 31mm back for a 50/50 distribution.
Solution: If space permits I’m going to add 4 links to the chain. Theoretically, this will move the rear wheel 32mm back. This is should be awesome as long as space permits.
Amazing. 30mm. Isn’t nice what a scale can tell you.
ps.
I took very accurate measurements of unsprung weight while I was at it. The devil is in the details.
Front unsprung weight – 43.3 lbs
Rear unsprung weight – 54.6 lbs