I carry a pair of Kahr's when riding.
A PM-40 in a pocket holster fits in either strong-side outer jacket pocket, or inner vest pocket - transferable because in the desert it starts out cold and gets real hot mid day.
A Kahr .380 in a wallet holster in the offside rear pocket.
The people I ride with do a lot of removing and putting on jackets etc. throughout the day as temps vary, but with these 2 pistols I can keep things completely concealed without any worries.
Here is the wallet holster. Awesome product for concealed back-up:
Hope this helps.