During the summer months, I rely on soft swimbaits to take river smallmouth bass, particularly when there is a hint of color to the water.
Soft swimbaits come in two basic styles. The most common configuration is the paddle tail, in which a shad profile soft bait is finished off with a boot-style tail. A good example is Yum's Money Minnow.
In this instance the tail wags the dog, fueling an enticing, natural swimming motion on the retrieve. The thinner, shiner-shaped paddle tail of the small version of the Money Minnow is most appropriate for smallmouth bass, not because smallies won't eat the broader, shad profile bait, but because the smaller bait is more in tune with the brown bass' smaller mouth, upping the hookup ratio.
A less popular but equally effective soft swimbait style is the segmented body. Here the bait is jointed, like the rungs of a ladder. Typically segmented baits feature two joints and a forked tail. These baits styles achieve their action by "swimming" as the bait moves at its hinge points. Segmented bodied swimbaits are thinning profile, similar in size to a shiner-shaped paddle tail. Lake Fork Tackle's Live Magic Shad is an outstanding swimbait of this sort.
Available in a wide assortment of lengths, soft swimbaits most appropriate for smallmouth bass run in the 3.5- to 4-inch range.
Proper rigging is a vital aspect of soft swimbait use, both to insure that the bait swims properly, and that your hookup percentage is acceptable. Yum markets a belly-weighted hook (Money Minnow Swimbait Hook) that works great when used in concert with the bait of the same name. Be sure to keep the hook centered as perfectly as possible for the best action from the bait.
I've found the Live Magic Shad to fish best for targeting smallmouth bass when rigged with a lead head jig in the 1/4 ounce range. Starting in the nose of the bait, run the jig hook through the middle of the bait's head and have it come out in the hook slot that's incorporated in the top of the head. This open hook arrangement ups the number of solid hookups. Incidentally, lead head jigs with fairly wide hook gaps work well when teamed with paddle-tail swimbaits.