I would say electrolytes are a bit off.
Bananas are a good start but I'm thinking you need
a bit more Potassium than you get with them.
Try drinking an electrolyte replacement drink
on your rides (like Gatorade, Accelerade etc.) If this
doesn't help you might want to look into
something like Endurolytes by Hammer products
E-Caps you can
get more info at the above site.
Marty