Hi,
I would normally say that blood glucose hits the blood more slowly if the carbs are eaten with fibre and or fat.
Do you know the fibre and fat content of your ryvitas and triangle?
Like you, I would have expected a smaller rise.
But on the other hand, my body seems to like to react more to grains that starchy veg. So in my case, I would have got a high rise from the ryvita, but a smaller rise if I had eaten potato.
Sorry, I'm probably not helping much!