Understanding reel seat sizing can be tricky, so here’s a guide to the reel seats that RODgeeks offers.
Spinning (also known as “barrel”) reel seats are the easiest to understand. They are sized based on their inside diameter in millimeters (with the exception of size 16, which has an inside diameter of 15.5 mm). As the inside diameter of the reel seat increases, so does the length and overall width of the seat.
Casting (also known as “trigger”) reel seats are a little more complicated, especially if they are designed to expose the blank above the trigger like ours are. With a spinning reel seat, if the seat that feels comfortable in your hand has a bigger inside diameter than your blank, you can use tape and epoxy to build the blank up and create a tight fit. But with an exposed blank reel seat you can’t do this because building up the blank would ruin the whole point of being able to feel it with your finger. Therefore, casting reel seats have two sizes- one that corresponds to the external size of the seat so that it feels comfortable in your hand, and another inside diameter size that ensures it will fit snugly on the blank.
This is why there are so many different “Size 16” and “’Size 17” reel seats in our lineup. For example, all of the size 16 reel seats are the same size externally (just look at the dimensions). What differentiates them is the size of their bore. An ECSM1611GBP seat has the external size of a size 16, but its inside diameter is only 11 mm at the bottom of the inner bore. Note that the bottom of a casting seat extends a little beyond the termination of the inner bore (about ¾ inch on Size 16, and about 1 inch on Size 17), so you want to match the inner bore of the reel seat to the diameter of the blank a little above where you want the external bottom of the reel seat to rest.
Once you understand how reel seats are sized, you can pick the one you want based on what will fit on your blank, what size will feel good in your hand, and what size will fit your reel. Again, all of these dimensions can be found on our website.
Happy Rod Building!