Yeah, I had to put a lot of thought into getting the fenders to work well on my Shogun 650B conversion. Definitely not plug-n-play.

The best way to determine clearance is to measure the clearance at 320mm from the axle. If there's going to be any rubbing of the tire on the chainstay or fork blade, that's where it will be. My bike had about 47mm clearance both front and rear, so that was my green light for Hetres.

My Hetres are measuring a true 42mm on Velocity Synergy rims. I think the older Hetre lots were labeled 41; the new ones are marked 42.