Motorhomers and boat owners (I am an 'ex' both of these) do a lot of fretting about lead acid batteries and there's a lot written about battery management in these fields, but they are simple to use and manage if you are kind to them.
The killer for a lead acid battery is not charging it - leaving them in a discharged state for any length of time causes them to sulphate, as does heavy discharging (regardless of the type of lead acid battery - 'deep discharge' batteries are mostly snake oil - they just have heavier plates to cope with the heating in heavy use). Multi stage chargers are good for taking care of your battery, but don't believe the 'de-sulphating' rubbish they all talk about - commonly regarded as snake oil. It's also harder to fully charge a gel battery fully, but some of their advantages outweigh this disadvantage.
The two golden rules for maintaining a healthy lead acid battery are:
Use the right charge rate (i.e. the correct rate for the type of battery - very different for wet cell and AGM / gel batteries - a decent multi stage charger should take care of this)
Don't use more than 50% of it's rated capacity i.e. for a 19Ah battery, don't use more than 9Ah of juice (I guess this was the case in subs Pukmeister?). This is the killer on a bike, because we don't have the space to store a big enough battery. Hence we nearly always end up torturing our batteries through over discharging through multiple staring loads and a shed load of electrical accessories. This is why they end up a consumable item on a bike.