It depends on the quality of your items, the extra weight you carry and the type of weapon or weapon/shield combo you choose to use, the amount of ride will also play into your mounted def stats. Information on ride can be found here. http://wotmud.wikia.com/wiki/Ride
Personally I feel 18 dex in dodge is a risky thing as you immediately handicap yourself from having maximum DB available as it is tied directly to you dex stat. While this is ok for channeler due to the offset DB obtained from armor as a normal non channeling class every single point of DB counts even more.
With 2h weapons you should be aiming for +130db +150pb (in dodge setup of camo hood/cloth sleeves/bskin tunic/earthen breeches/dark gloves/silver tooled boots/obsidian necklaces/gold rings/cbelt/red robe/kcuffs)
if you want to compete in pk, however dodge short of 140db is going to see you get sat and eaten alive a lot by master bashers/fades and mounted bashers with large weapons. With 1h weapons such as fblades/sblades/longs/meds you might find yourself above 160pb
depending on your practices.
In combo you could obtain about 90db 140pb with 60% abs in an top end kit (obsidian necklaces/gold rings/cbelt/red robe/kcuffs/rimmed helmet/riveted set/finely tunic/animal fur boots/sturdy leather gauntlets)
Depending on your choice of weapons, you'll find sblades will have lower defense than say 1h longblades while 2h weapons will again likely have lower defense at the cost of better bashing/damage or practice options due to not requiring shield parry to be effective.
There are many things I still don't know myself but I hope this at least gives you some idea.