I recently bought and mounted a set of the Planet Bike Cascadia ALX 650bx60mm fenders on my bike and thought I'd give a review for those searching for a low cost aluminum fender.
Front and rear fenders were mounted on a Soma Wolverine v2.1 running WTB Frequency Team i23 (23mm wide) rims with WTB Horizon 650bx47 tires.
Specs for the fenders indicate that they can fit tires up to 1.9" (48mm) wide and they had generous clearance with the rims and tires used.
The main issue with these fenders is that the radius is absolutely incorrect for 650b wheels. It seems to me that the radius is actually 700c wheels with wide tires. When I first mounted the rear fender, the mud flap was easily 3-4 inches behind the tire. The fenders have a stiffening ridge that runs down the center which, on top of the thicker than usual metal, made decreasing the radius impossible though the usual means. I had to push the fender in with one hand and tighten the stays, which are a little on the short side.
The front fender had the same issue with radius. Additionally, the mounting tab that is too short for a lot of fork crowns so the fender sits high above the tire. The fork the fender was mounted on is the standard style Soma Wolverine fork (not the through axle unicrown fork) that is designed for 700c wheels with larger tires so this wasn't completely unexpected. It would seem that many bikes running 650b are actually designed for 700c so a longer mounting tab would be very beneficial. As a result, the leading edge of the front fender sticks up a few inches above the tire. The stays on the front fender are too short as well which only serves to exacerbate the fitting problems.
What is good about these fenders? They are definitely beefy. I rode with them for around 120 miles this past weekend with around 80 of those miles being on gravel and they did not creak or rattle even once. They also have cutout areas on the rear fender to accommodate chain stays and chain. However, the drive side cutout was not long enough to accommodate a front derailleur so I had to get creative with washers on a long bolt to avoid the derailleur hitting the fender and pushing it into the wheel. I tried filing away material to avoid this but after around 1/4" of material was filed away, with a hand file, I gave up and simply moved the rear wheel back and spaced the fender away from the seat tube. I will re-visit modifying these later to maintain a shorter wheelbase on this particular bike. They also come with a lot of mounting hardware to help clear disc brakes.
Coverage wise they are what you'd expect. They are not full coverage so your feet are going to get wet in the rain. There is a thicker lip on the inside of the fenders to help channel water inside of the fender but it is a gradual ramp so there still may be some spray from the sides.
In short: I'd likely go with something else if I had to do it again. They are a pain to mount, have an incorrect radius, stays that are almost too short, a too short front mounting tab, and they are heavy. With Velo Orange coming out with new 650b Wavy fenders in the near future, I'd probably elect for those as a lower cost option (assuming they will be priced in line with their other fenders). I'll likely run these until they are either damaged or I decide to throw more money at fenders.