As I'm riding my bike, it looks as if the rear tyre is carrying more weight than the front tyre: The rear tyre looks more squished downwards, even though both are equally well-inflated.
This I think has been true for every bike I've had.
Am I just imagining it or is this generally so?
Might this also explain why the rear tyre is more susceptible to wear and tear than the front?
Generally, the weight distribution of a rider on a bicycle is something like 40 - 60 rather than 50-50 (front to back). This contributes to increased rear tire wear (along with rear wheel drive) causing front tires to sometimes last three times as long as rear tires. Skid stops (such as on a fixie) can also increase rear tire wear relative to normal stops.
An aside: You don't need to run your tires at equal pressure - in fact, in most cases, the rear tire is about 10% higher than the front tire. This will make it deflect a bit less.
Stand your bike against the fence and step away. Most of your weight is on the seat and seat is closer to the rear wheel. Second the weight is on the pedals and they are closer to the rear wheel. Third the weight is on the handle bar and the handle bar is closer to the front wheel. The only time more weight is on the front wheel is when you lean on the handle bar - nice for hopping the rear wheel over a curb.
Bikes are designed with more weight on the rear so you don't go over the front easily when you jump on the front brake.
Tire wear is also about how you brake and more braking is done by the rear wheel because it is more stable to brake with the rear even though the front has more braking power.
If you look at this image
and draw a vertical line right down the center between the two wheels, you will see that only the part of the rider's body from the shoulders up is ahead of the line -- easily 2/3rds of the weight of the rider is rear of that center line.
(And I don't know if the numbers work out to make it significant, but keep in mind that when the cyclist applies power to the crank that creates a force vector that shifts more downward force to the rear wheel.)
When a cyclist gets in an aero tuck, however
the balance can get close to 50/50.
