Maybe an average of 49% of win. (why not on an exponential? example: 90% of win with a bet of 0.01 BTC and 20% with 0.50 BTC, almost 49% in average). In all cases you haven't really 49% chances of win. It's a fake coin flipping.
Example with minimum bet at 0.01 and maximum bet at 0.50 on an exponentialAverage: 49% chances of win.