"Why does everyone keep trying to foist a trickle charger on me? I've been driving my car for twenty years and no one mentions battery chargers?"
It's a fair comment, to which there is a good and clear answer: that car battery is losing capacity too, just like the motorcycle battery. Only that last one has a much smaller capacity, so you'll notice the consequences a lot quicker.
Every battery discharges itself. And with a motorcycle, that leads to an drained battery relatively quickly.
So, if you only ride occasionally or store the bike for months at a time, connect the battery regularly to a battery charger. Afterwards, your motorcycle will start without any problems.
At RAD, we have a number of high-performance trickle charger brands. We also have a whole range of extra cables available for all our battery chargers.